# Forum Home Renovation Heating & Cooling  Duct Repair/Replacement Options

## Grasshopper75

Hi everyone, 
I am wanting to replace some underfloor ducting for my gas ducted heating system before winter arrives. We purchased the house 12 months ago and have been through one winter during which the original heating unit died. I replaced the unit with a more efficient system and was also hoping it would improve the airflow. Unfortunately after finally finding access to under the house (it was well hidden) I noticed alot of the ducting is in need of replacement and the likely cause of the airflow problems. My biggest issue right now is that access under the house is going to be very difficult with most access being of 1 foot or less. 
What options do I have to replace the ducting and can anyone recommend someone in Melbourne's Eastern suburbs? The house has been renovated and restumped so at some point somebody was able to get under there but I am hoping someone could give me some tips to ask and to look out for when obtaining some quotes? Due to the limited space, I am yet to get under and have a proper look, I'm not even sure if its going to be possible, however I have attached some photos of what I have discovered so far. If access under the house is not possible would they need to lift floorboards? 
Any help would be greatly appreciated. 
Thanks

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## Moondog55

Can you find some willing young ( = small) teenagers to get under there and move all that loose dirt?
Worth paying some-one a few hundred to do it as it would improve clearance.

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## johnc

We are going through the same process with a similarly restricted space. Ducting is not meant to touch the ground, should be well supported and properly sealed on the joins. Modern ducting is also thicker than the old style, in our case that means replacing 30 plus yo with something much thicker that will not fit regardless of worrying about it touching the ground.. We have totally given up on the idea of trying to get it through the subfloor and will be putting a new ceiling ducted system in, using maximum efficiency ducting and a five plus star system. What we have done though is rip out the old system and under masters (same as that Xpol happy feet stuff) underfloor insulation throughout, a dirty crappy job but well worth it. now all we have to do is instal the new system before winter.

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## Grasshopper75

> We are going through the same process with a similarly restricted space. Ducting is not meant to touch the ground, should be well supported and properly sealed on the joins. Modern ducting is also thicker than the old style, in our case that means replacing 30 plus yo with something much thicker that will not fit regardless of worrying about it touching the ground.. We have totally given up on the idea of trying to get it through the subfloor and will be putting a new ceiling ducted system in, using maximum efficiency ducting and a five plus star system. What we have done though is rip out the old system and under masters (same as that Xpol happy feet stuff) underfloor insulation throughout, a dirty crappy job but well worth it. now all we have to do is instal the new system before winter.

  Thanks for the reply John. Yes I understand it is not meant to be touching the ground but I don't really have a choice. I wish I had known how bad the problem was when I replaced my heater but we did consider going through the roof. The roof is not really an option for two reasons 1) I have ornate ceilings in the front half of the house and wouldn't want vents punched through the ceilings 2) the back half of the house is renovated and the roof is essentially two pitched roofs that meet in the middle. One guy told me I would need two separate systems or would need to run stuff on the outside of the house. So essentially its been ruled out. 
Having only bought the house 12 months ago I think this will be the thing that bites me the hardest. I had a building inspection done and whilst it did highlight some things I was willing to accept, I never thought about the heating as the house was on the market at the start of summer (smart vendors!). I've already spent $2.5K going down this path so I think I now have to finish the job. I just have no idea how anyone is going to get under the house to do it. 
I had another look from some different areas of the house and believe it's only the front halve of the house that needs new ducts. However I also noticed that it appears one of the ducts is cut in half and wide open, which would explain why there is no airflow in this room and the coldest in the house. 
I'll just have to bite the bullet and get some quotes next week and see what happens, but I'm starting to now realise why the previous owners wanted to sell!

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## Grasshopper75

After shining a torch into one of the vents, I have just confirmed why worst fears, one of the ducts is completely cut in half, leaving a gaping hole. The worst thing is that it is on the opposite side of the house to the sub-floor access point and also with the most restricted space. This is going to get expensive! Not happy!!  :Mad:  :No:  :Annoyed:

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## krico

I think that this jobs is doable.  
Is the one foot measured from joists, bearers or floor? Does it get any better than this where it is fed/returned to the heater? What sized duct is coming off the heater? How many outlets do you have in the house? 
Things to consider are:
- Ducting - R1.65 is what you should go for as most efficient. You may need to consider R1 or R0.8 for the tighter areas. Duct should never lay on the ground but in some cases, this is unavoidable but can be done. Ensure that the duct is hung every 30/40cm as over time it settles and if not hung at this spacing, will settle to a point where it affects efficiency. 
- Is the return air correctly sized for your new unit?
- Condition of floor boot and BTO insulation. Due to age, fair chance that insulation on these is degraded and may need replacement. 
- Current design - Can this be changed or improved? A good design in my opinion is worth its weight in gold. This may lead to replacing the above items, but well worth it. Have you considered zoning your system?
- I assume you have an external heater? 
Dont discount the ceiling option. You can get decent diffusers that suit different period ceilings and do look allright. As to getting it through,consider using a cupboard, even building a bulkhead etc. Anything is possible with a bit of thought and knowledge.  
This will be labour intensive as you know and will cost you more. If you are going to do it, try and get it done well with a good design and decent duct and duct work. Also ask if there is anything you can do to lower the cost, as Moondog suggested clear some rubble away or even remove the old stuff yourself. Even be prepared to remove the external timbers around the house to make access easier for them. To come in from one side and go fifteen metres compared to pulling a few timbers off and only needing to go in a few will make a huge difference.  
You dont have a lot of room and a lot of blokes will take one look at this and knock it back. If you find a decent installer, they will get this done. I did a job a year or so ago on a 100 year old church where in some positions, the bearers were sat on the deck. We had to dig trenches through and then drag everything through, hook it up and then reverse our way out. Only way to do it and worked well. On another job, client wanted an outlet in the bathroom. No access to the room in the subfloor due to foundations, so we cut a hole through the foundations, and used 150mm PVC sewer pipe to feed the outlet. Obviously not insulated and not a long run to it either. We also zoned this outlet so it was only on when it needed to be. 
Hope this helps.  
Krico

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## Grasshopper75

> I think that this jobs is doable.  
> Is the one foot measured from joists, bearers or floor? Does it get any better than this where it is fed/returned to the heater? What sized duct is coming off the heater? How many outlets do you have in the house? 
> Things to consider are:
> - Ducting - R1.65 is what you should go for as most efficient. You may need to consider R1 or R0.8 for the tighter areas. Duct should never lay on the ground but in some cases, this is unavoidable but can be done. Ensure that the duct is hung every 30/40cm as over time it settles and if not hung at this spacing, will settle to a point where it affects efficiency. 
> - Is the return air correctly sized for your new unit?
> - Condition of floor boot and BTO insulation. Due to age, fair chance that insulation on these is degraded and may need replacement. 
> - Current design - Can this be changed or improved? A good design in my opinion is worth its weight in gold. This may lead to replacing the above items, but well worth it. Have you considered zoning your system?
> - I assume you have an external heater? 
> Dont discount the ceiling option. You can get decent diffusers that suit different period ceilings and do look allright. As to getting it through,consider using a cupboard, even building a bulkhead etc. Anything is possible with a bit of thought and knowledge.  
> ...

  Thanks Krico, that gives me some hope at least. 
To give some further background, the original front part of the house is a 1930's weatherboard cottage with wooden floorboards. About 8 years ago the previous owners put on an extension out the back of the house and continued the weatherboard and floorboards throughout. At this point they relocated the old Brivis Buffalo 85 system and continued the duct work to the rooms in the extension. (The entire house was also restumped with concrete stumps.) I now have a total of 11 outlets, 5 in the front, 6 in the back. The outlets at the back of the house seem OK but I can only determine this based on airflow and heating of the rooms as I cannot see these ducts.  
The old Buffalo packed it in at the end of winter last year and was replaced with a Brivis StarPro Max and new controller, however no other changes were made at this time. When I was sourcing quotes one guy mentioned that the Buffalo 85 and the air return were too small for house after the extension but he didn't end up getting the work because he was making out that everything else was too hard (maybe he was right?) and I needed a quick and easy solution. To be honest though I am a little disappointed with the installer I went with only because they could have advised me better. I'm happy with the unit but if they had highlighted the same issues that the first guy had then I would have rethought what I needed to do. 
The space under the floor varies significantly and there are many peaks and troughs with the dirt. I have started to dig out some of it but it is still proving rather difficult. The access point itself is only 23cm high because of a new driveway so I haven't squeezed myself fully under there yet as I'm afraid I might never get out! This access point is actually where the old heater was positioned originally before the renovation. Access is really only available from here unless I start digging trenches on the other side but that is likely to be a problem also with gas lines nearby. I assume most of the underfloor work was done during renovation and would now require lifting decking, floorboards or digging to get access from anywhere else. I think my only options are to dig out the dirt by bringing it back out the way I came in, lifting floorboards or going into the roof. Going to the roof is also going to be difficult as the only possible places to run ducting is central to the house.  
Either way, it's likely to be a difficult and expensive job. Any ball park figures to do 5 outlets and possibly a bigger air return if going under the house? 
Thanks again.

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## krico

> Thanks Krico, that gives me some hope at least. 
> To give some further background, the original front part of the house is a 1930's weatherboard cottage with wooden floorboards. About 8 years ago the previous owners put on an extension out the back of the house and continued the weatherboard and floorboards throughout. At this point they relocated the old Brivis Buffalo 85 system and continued the duct work to the rooms in the extension. (The entire house was also restumped with concrete stumps.) I now have a total of 11 outlets, 5 in the front, 6 in the back. The outlets at the back of the house seem OK but I can only determine this based on airflow and heating of the rooms as I cannot see these ducts.  
> The old Buffalo packed it in at the end of winter last year and was replaced with a Brivis StarPro Max and new controller, however no other changes were made at this time. When I was sourcing quotes one guy mentioned that the Buffalo 85 and the air return were too small for house after the extension but he didn't end up getting the work because he was making out that everything else was too hard (maybe he was right?) and I needed a quick and easy solution. To be honest though I am a little disappointed with the installer I went with only because they could have advised me better. I'm happy with the unit but if they had highlighted the same issues that the first guy had then I would have rethought what I needed to do. 
> The space under the floor varies significantly and there are many peaks and troughs with the dirt. I have started to dig out some of it but it is still proving rather difficult. The access point itself is only 23cm high because of a new driveway so I haven't squeezed myself fully under there yet as I'm afraid I might never get out! This access point is actually where the old heater was positioned originally before the renovation. Access is really only available from here unless I start digging trenches on the other side but that is likely to be a problem also with gas lines nearby. I assume most of the underfloor work was done during renovation and would now require lifting decking, floorboards or digging to get access from anywhere else. I think my only options are to dig out the dirt by bringing it back out the way I came in, lifting floorboards or going into the roof. Going to the roof is also going to be difficult as the only possible places to run ducting is central to the house.  
> Either way, it's likely to be a difficult and expensive job. Any ball park figures to do 5 outlets and possibly a bigger air return if going under the house? 
> Thanks again.

  23cm access isrestrictive in many ways, of getting yourself and the gear in. You may have toconsider cutting a manhole in the floor somewhere where you think there isdecent clearance underneath and then going from there. Even if they need to diga pit underneath to get everything in. You can also temporarily remove theheater and access there where the duct is going through. This should be adecent size to get air to 11 outlets and should be at least 14" duct atthis point. (depending on what size duct they have running to each outlet).  
I dare say that everything is going to be undersized now because of theaddition and you may need to look at doing the whole lot again. It could beallright but 
with the duct being so old a complete re-duct may be in order. You have purchaseda good heater and it is really going to waste with the duct the way it is now. 
If you dont get this done before winter, I would suggest that you go under andtie off the ends of the broken duct. That is at least a start to saving energy. 
Even a ballpark figure is hard to give as there are so many variances to takeinto account. Duct quality, labour, design, length of runs and the list goeson. 
I still think it is possible to do this and achieve a decent outcome butprobably need someone to have a look under there at the design and what needsreplacing and go from there. If they say that the design is good and sized welland only need to replace duct, there is no reason (if you can get under thereyourself and want to do it) to have a go at it yourself. Duct, duct tape,hanging tape and a stapler are the main items. There are plenty of places tobuy this from and you can get it fairly cheap too, depending on quality.  
Krico

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## Grasshopper75

I've gone right around the house and taken a few baseboards off and can see some of the ducts from different angles. Still very limited in what I can see though. The rear of the house looks fine, the ducting is suspended and looks to be in good condition. As for the front of the house, the ducting is shredded in quite a few places and crushed in others.  
So I think a redesign of the duct work will definitely be necessary. I believe I have 14" ductwork throughout. I have some ducts running over the top of others in what is an already restricted space so essentially at these points the airflow is halved, as well as ducting being crushed. The local cats have got to it over time (I actually saw one sitting on the ducting last winter) though I believe I have plugged up all the holes where they were getting in. 
How is it meant to be designed though? About the only thing I understand is the return air but I don't really know if you can put forks or junctions in or which vent should be connected first so I think I will just have to get some quotes and see what comes of it. I want to do it properly so I will probably ask for them to increase my return air also but unfortunately due to the floorboards being cut I think it will need to stay where it is at the front door.  :Frown:  Supposedly it's not a great place for it and it's meant to be more central? 
I don't think I really have a choice of not doing it before winter as I can't get access to the broken ducts without removing others and I really want the house warm for winter without wasting $$$ leaking hot air! 
Thanks for your help Krico. I'll report back soon.

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## Uncle Bob

Going by those pics, under that house looks absolutely luxurious compared to some of the places I've been under. Some you couldn't even turn yourself over in. 
You could make more room by pushing the dirt either side, though I'd possibly remove it for easier access next time. If you have a helper, you can use a crate with a rope on each end. They pull it out and empty it, you pull it back in and fill it up. 
Watch The Great Escape movie for some hints  :Smilie:

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## krico

> I've gone right around the house and taken a few baseboards off and can see some of the ducts from different angles. Still very limited in what I can see though. The rear of the house looks fine, the ducting is suspended and looks to be in good condition. As for the front of the house, the ducting is shredded in quite a few places and crushed in others.  
> So I think a redesign of the duct work will definitely be necessary. I believe I have 14" ductwork throughout. I have some ducts running over the top of others in what is an already restricted space so essentially at these points the airflow is halved, as well as ducting being crushed. The local cats have got to it over time (I actually saw one sitting on the ducting last winter) though I believe I have plugged up all the holes where they were getting in. 
> How is it meant to be designed though? About the only thing I understand is the return air but I don't really know if you can put forks or junctions in or which vent should be connected first so I think I will just have to get some quotes and see what comes of it. I want to do it properly so I will probably ask for them to increase my return air also but unfortunately due to the floorboards being cut I think it will need to stay where it is at the front door.  Supposedly it's not a great place for it and it's meant to be more central? 
> I don't think I really have a choice of not doing it before winter as I can't get access to the broken ducts without removing others and I really want the house warm for winter without wasting $$$ leaking hot air! 
> Thanks for your help Krico. I'll report back soon.

  A decent design should see you being able to have the duct work being installed without having to cross over other duct. Where the return air is can always make this difficult to accomplish. Essentially what you are looking for is air flow throughout the house to be the same, in both quantity of air and also noise. This means balancing the system either by duct design or through manual dampers which are blades inserted in the ducting to restrict air to some parts and force it to others. When we install, we have a air flow meter that we use to test all the outlets for how much air in L/s is coming out. We then try and balance the system to ensure airflow is even across all outlets. A poor design can see one outlet getting a lot of air and noisy, then another outlet getting no air at all.  
You will have duct work of various sizes starting big at unit and then getting progressively smaller as it branches out. Your actual outlets into your rooms right now are more than likely 6" or possibly 8" for slightly bigger rooms. You have the option to add "add-on" cooling with your heater so if you are going to redo the whole lot, minimum size into each outlet needs to be 8" as you need more cycles of air for cooling to be effective. It just wont work with 6" for this many outlets. If you set the duct work up like that now, it is a simple addition later on when funds permit. Also consider at this point, zoning the system if you have rooms that you dont want to heat during the day, for example, bedrooms. You can run two zoning dampers off the main unit board as it stands right now. If you go more than this, you need to buy another zone control kit. This is assuming that you have an NC3 controller and not just a manual one.  
You are right about the return air in that it should be in a central location. It sounds like yours is in the floor. What you could consider is having it bought up in a cupboard that also joins say a hallway (if you have this option). You will lose part of your cupboard, but it also means that your return air can be wall mounted. Essentially part of the cupboard will get boxed out to form a void for the return air.  
Hope this helps.  
Krico

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## Grasshopper75

Fantastic Krico. Thank you. 
I totally forgot about the cooling option and definitely want to factor that in to the quotes. I might have some options too for a new location for the return air, the only thing is what to do with the old one in the floor? I guess I could always seal the box and leave it there? 
I also have the Birvis Networker NC-3 controller so I should be good  with the cooling add-on and zoning. I had initially discarded the idea  of zoning but I think you have made some very valid points to make me  want to think about it again. Cost is always a concern but if I am going  to do it I may as well spend the money to get it right and hopefully  save some $$$ in energy costs down the track. 
Now finally, the majority of vents are positioned on outer walls under windows. Is this normal/recommended? The only reason I ask is that due to space restrictions I might consider moving a vent in my son's room to the inner wall. Looking at it under the house it looks like its quite cramped as there is very little space at this side of the house and the ducting has to run up over some plumbing. If the vent was moved to the inner wall it would likely have much better airflow. Is this something I should ask for? 
Thanks once again for your feedback. It has been a massive help and greatly appreciated.

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## Grasshopper75

> Going by those pics, under that house looks absolutely luxurious compared to some of the places I've been under. Some you couldn't even turn yourself over in. 
> You could make more room by pushing the dirt either side, though I'd possibly remove it for easier access next time. If you have a helper, you can use a crate with a rope on each end. They pull it out and empty it, you pull it back in and fill it up. 
> Watch The Great Escape movie for some hints

  Yep this was what I was thinking Bob. My main problem is getting under the house first but I think it's doable once I remove some brick edging. Once I removed some baseboards it is evident that there are already some channels under the house although I would still need to remove quite alot of dirt. Definitely need some overalls, goggles and facemask I think. Just digging around on the edges and I was getting a face full of dust.

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## Moondog55

Going back to my first reply, to me it looks like a lot of the lack of clearance is due to the restumping that seems to have been done. Clearing all the loose dirt from underneath the house will improve things quite a lot. When we restumped we insisted on all the dirt being removed and while a lot of grumbling took place; most of the dirt got removed; makes getting under our house a little easier

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## Grasshopper75

> Going back to my first reply, to me it looks like a lot of the lack of clearance is due to the restumping that seems to have been done. Clearing all the loose dirt from underneath the house will improve things quite a lot. When we restumped we insisted on all the dirt being removed and while a lot of grumbling took place; most of the dirt got removed; makes getting under our house a little easier

  Ahhh.. that makes sense!! I never even thought of that. Thanks Moondog, although I will still be the one to be shovelling it it seems.

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## krico

> Fantastic Krico. Thank you. 
> I totally forgot about the cooling option and definitely want to factor that in to the quotes. I might have some options too for a new location for the return air, the only thing is what to do with the old one in the floor? I guess I could always seal the box and leave it there? 
> I also have the Birvis Networker NC-3 controller so I should be good  with the cooling add-on and zoning. I had initially discarded the idea  of zoning but I think you have made some very valid points to make me  want to think about it again. Cost is always a concern but if I am going  to do it I may as well spend the money to get it right and hopefully  save some $$$ in energy costs down the track. 
> Now finally, the majority of vents are positioned on outer walls under windows. Is this normal/recommended? The only reason I ask is that due to space restrictions I might consider moving a vent in my son's room to the inner wall. Looking at it under the house it looks like its quite cramped as there is very little space at this side of the house and the ducting has to run up over some plumbing. If the vent was moved to the inner wall it would likely have much better airflow. Is this something I should ask for? 
> Thanks once again for your feedback. It has been a massive help and greatly appreciated.

  Glad to help.Your controller will be good for add-on cooling and running a few zones. There really is not too much cost to the zoning in the set-up, and again depends on the quality of the zoning damper. These will be 24V that run directly off the main PCB. If you can afford it now, I would get them put in as it will be more expensive later on. And this needs to be talked about when quoting and if the ductwork is redesigned. If they are going to redesign, get them to draw you a layout of the ducting and show exactly where the zoning dampers are going to be placed so you know what rooms are going to be zoned.  
You could always leave the current return air where it is and just make sure it is sealed off properly. If you redo the floors at some stage, then fill it in.  
The positioning of your vents is correct. Generally they should be placed in a position furtherest from the door so that full efficiency can be gained, ie you dont want the hot/cold air going straight out the door before actually heating/cooling the room. The normally go under windows as this is generally a point of entry for heat/cold, furniture is not normally placed there and generally the furtherest point from the door. You could move the outlet in your sons room, but if we have to put an outlet in a room not on the furtherest wall, we tend to install a floor register (the outlet part) that is directional and forces the air to that wall anyway to put more air into the room rather than straight out of it. Sometimes it just cannot be avoided and you just have to put it where you can. Always need to remember though that you are limited by joists and bearers and whatever else you may have underneath, plumbing, wiring etc etc.  
And as Moondog and Bob have mentioned, if you can make it easier by giving more room it may very well be cheaper in the end.

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## Grasshopper75

OK so the guys who installed my new heater came back to have a look at my issues and as it was the first time around they didn't really have any good news for me. Basically I need to get 400mm clearance under my house so they can get access if I want to keep the floor vents. The only alternative is to dig a channel to the central cupboard and  put the heating into the roof for the front part of the house. Either way, I need to get under and start digging. This is going to be an almost impossible task but I have no choice but to give it a go! How far I get will determine whether I keep the floor vents or am forced to go to the roof. 
Stupid question, but does anyone have any recommendations on equipment to use apart from a trowel and bucket? I'm going to be flat on my stomach trying to do this and it won't be fun! 
Also add-on cooling has been ruled out entirely unfortunately due to restrictions on where the heater is located. Since there is nowhere else to put it, I lose out! The cost of the add-on cooling also made it a difficult pill to swallow. 
The previous owners really did a number on this one!! Not happy at all.  :Mad:

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## Moondog55

Yep. As Bloss suggested in another thread, a couple of young teenagers.  
Get a helper or three; it makes things three times as fast. A big but shallow tray with a rope at each end. 
Determine the duct layout
Find a place with better access as close as you can to the furnace point. Start digging from the outside in and clearing as wide and deep a path as you can. Fill the shallow cart as you go Mate pulls out the dirt carriage when you shout at him, then you pull it back when he has emptied it.
Seriously I would make a start and then throw a few slabs in the fridge and get as many people around for a beer and sausage fueled working bee as quickly as you can.

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## krico

> OK so the guys who installed my new heater came back to have a look at my issues and as it was the first time around they didn't really have any good news for me. Basically I need to get 400mm clearance under my house so they can get access if I want to keep the floor vents. The only alternative is to dig a channel to the central cupboard and  put the heating into the roof for the front part of the house. Either way, I need to get under and start digging. This is going to be an almost impossible task but I have no choice but to give it a go! How far I get will determine whether I keep the floor vents or am forced to go to the roof. 
> Stupid question, but does anyone have any recommendations on equipment to use apart from a trowel and bucket? I'm going to be flat on my stomach trying to do this and it won't be fun! 
> Also add-on cooling has been ruled out entirely unfortunately due to restrictions on where the heater is located. Since there is nowhere else to put it, I lose out! The cost of the add-on cooling also made it a difficult pill to swallow. 
> The previous owners really did a number on this one!! Not happy at all.

  400mm clearance to keep underfloor ducting? I guess that if they are all you have, you will have to get the clearance. If you were any closer to me, I could get it done for you.  
And why have they ruled out the add-on cooling? I dont understand the part about "restrictions on where the heater is located". Unless you have no room to put another outdoor unit about the same size as the heater, why will it not work? 
Maybe you could get under and loosen the dirt and get in a big hydrovac unit or similar to vac all the dirt out? 
Krico

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## davegol

we had exactly the same situation as you. 1930s w/board, 20cm off the ground, no access at all. we renovated and added a new back section with good clearance. we were going to extend the heating system, but in the end it wasn't strong enough (even though they told us initially it would be!) so we added a secondary system and just reconfigured the ducts for the old system to fit the new rooms. Glad we went with that approach and fortunately we moved the ducts when the floors were already lifted up - still required a fair bit of digging but luckily we could use wheelbarrows. 
At the time I asked the builder about getting access underfloor and his suggestion (which he said he usually does) is to put in a manhole in the middle of the fridge cavity (just don't go too close to the edges, or you'll end up with a very low fridge!). That way you never see it, and when you need it you can move the fridge and get under the floor. It might we worth considering in your case if you can't get access through the side wall. 
good luck mate!

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## Grasshopper75

> 400mm clearance to keep underfloor ducting? I guess that if they are all you have, you will have to get the clearance. If you were any closer to me, I could get it done for you.  
> And why have they ruled out the add-on cooling? I dont understand the part about "restrictions on where the heater is located". Unless you have no room to put another outdoor unit about the same size as the heater, why will it not work? 
> Maybe you could get under and loosen the dirt and get in a big hydrovac unit or similar to vac all the dirt out? 
> Krico

  Yeah Krico, they said minimum 350mm-400mm if they are going to do it. These guys were not prepared to get under the house the way it is now.  It is a very tight squeeze and I'm basing that on the high side of the  house which I can see. I need to get under there to see what the rest of  it is like. I can only get in from one side so I'm going to need to crawl the entire width of the house to get to some vents. 
With regards to the cooling unit, there is only really one spot around  my entire house for the heater and there is no additional room for the  cooling unit they reckon. 
When I asked what the ballpark figure was for the add-on cooling I was told $10K! I can't justify spending that anyway so it doesn't really matter in the end. I think I will just live with my existing reverse cycle A/C unit for cooling and use the fan in the heater to move the cool air around the house. Not ideal but I'll live. 
I think I will proceed with trying to dig out as much as I can myself and then make some decisions after that. 
First photo shows the best entry point under the house, if I removed some of the brick edging that should allow me to get under there. Second photo shows the one and only place for the heater, with no room for add-on cooling. Third photo is the other side of the house with almost no clearance under the house.  Attachment 96195

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## Grasshopper75

> we had exactly the same situation as you. 1930s w/board, 20cm off the ground, no access at all. we renovated and added a new back section with good clearance. we were going to extend the heating system, but in the end it wasn't strong enough (even though they told us initially it would be!) so we added a secondary system and just reconfigured the ducts for the old system to fit the new rooms. Glad we went with that approach and fortunately we moved the ducts when the floors were already lifted up - still required a fair bit of digging but luckily we could use wheelbarrows. 
> At the time I asked the builder about getting access underfloor and his suggestion (which he said he usually does) is to put in a manhole in the middle of the fridge cavity (just don't go too close to the edges, or you'll end up with a very low fridge!). That way you never see it, and when you need it you can move the fridge and get under the floor. It might we worth considering in your case if you can't get access through the side wall. 
> good luck mate!

  That's actually a good idea but unfortunately won't work in my case as the fridge is right above the ducts for the heater itself. I've heard of people making a manhole in the floor inside a cupboard or walk-in robe also. 
I am just not having any luck with finding a solution really. If I can't dig it out I really don't know what I'm going to do.

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## krico

When they installed the heater (and is it a 23kW) did they cut away the concrete between the heater and the house?

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## Grasshopper75

> When they installed the heater (and is it a 23kW) did they cut away the concrete between the heater and the house?

  This is the start of the back part of the house (new reno) so there is more clearance here than the front of the house (old original). Also due to the new driveway, the clearance is now even less. I also managed to get more of a look at the ducting in the back and it is totally fine, it's just the front of the house and as mentioned earlier I think when they restumped the front of the house they simply left all the excess dirt & material under there. As the back of the house was built, they cleared the area which gave enough clearance for the ducting. It does touch the ground in some places but the majority of it is suspended off the ground. When the new heater was installed I asked them to look at the ducts and if all they could see were the ducts in the back of the house then they too would have thought it was fine. They should have picked it up something though when they tested the airflow on the vents. Regardless though I would be in the same place as now, trying to figure out how to fix it!

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## krico

My point was that the duct spigot on a 23kW is 12" and then add insulation and your clearance between the concrete and house does not appear to be that. There is a chance that this has been jammed through that gap if the concrete was not cut back. Restriction in air right there at the start.

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## johnc

There is nothing easy about digging under the house, we fashioned an old narrow spade up by removing the wooden handle and welding on a lump of steam pipe and using the heft to break up the dirt then a normal spade to shovel it into a container to drag out. That gave us some access through a new hatch in the Laundry. We also took advantage of a kitchen reno to remove some floorboards so we could drop through underfloor insulation and instal that while removing half the old ducting at the same time. In places the only way to get through is to turn your head to one side so your nose doesn't jamb on the way through and breath in, you wouldn't want a stomach bigger than your chest or you can't get through either.  
Good luck with the digging but watch your shoulders, you will be using muscles in ways they are not used to and you can end up with a range of strains and injuries through over reaching or pressure.

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## goldie1

Be careful you don't end up with a channel which will divert water under there. 
Have a read of a few WW2 escape books plenty of advice there about removing dirt from confined spaces :Smilie:

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## Grasshopper75

> There is nothing easy about digging under the house, we fashioned an old narrow spade up by removing the wooden handle and welding on a lump of steam pipe and using the heft to break up the dirt then a normal spade to shovel it into a container to drag out. That gave us some access through a new hatch in the Laundry. We also took advantage of a kitchen reno to remove some floorboards so we could drop through underfloor insulation and instal that while removing half the old ducting at the same time. In places the only way to get through is to turn your head to one side so your nose doesn't jamb on the way through and breath in, you wouldn't want a stomach bigger than your chest or you can't get through either.  
> Good luck with the digging but watch your shoulders, you will be using muscles in ways they are not used to and you can end up with a range of strains and injuries through over reaching or pressure.

  The plan is for overalls with knee pads, face mask and goggles. Just digging out near the opening was bad enough with all the dust. The previous owners had the perfect opportunity to do things right when they put the extension on but obviously decided to cut corners and leave the crap for the next guy, ME! The rear of the house is still tight but it's flat, clean and ducting is suspended. It's a totally different story at the front of the house. Someone had to have got under there at some point and I can only assume they did it when they had front, side and rear access during renovations. Now I'm limited to one access point and having to crawl the entire width of the house!

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## johnc

I stuck with long pants, shirt and beanie, overalls are a pain under a house when you have to stretch. In some places though I found it easier on my back working out to the side, always though with a dust mask and head lamp there is very little light. The crap in your photo looks dreadful, there is simply no excuse for leaving that type of mess, our underfloor is clean and the house has had two renos since we built it and we made sure it remained clear and flat, it was bad enough dragging out the dirt from the trench we cut plus the portion of old ducting. I worked as a labourer with a shovel digging plumber and electricians trenches during my Uni days so I'm no stranger to the joys of digging but I did find the awkwardness under the house less than enjoyable. 
The fact that someone has cut a duct and not closed it off or reconnected it is reprehensible, you must have spent a fortune heating the underneath of the house, no wonder you have had cats in there. All up I would feel like taking a section of duct and inserting it into whoever was responsible for the destruction of the existing ducting.

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## Grasshopper75

> I stuck with long pants, shirt and beanie, overalls are a pain under a house when you have to stretch. In some places though I found it easier on my back working out to the side, always though with a dust mask and head lamp there is very little light. The crap in your photo looks dreadful, there is simply no excuse for leaving that type of mess, our underfloor is clean and the house has had two renos since we built it and we made sure it remained clear and flat, it was bad enough dragging out the dirt from the trench we cut plus the portion of old ducting. I worked as a labourer with a shovel digging plumber and electricians trenches during my Uni days so I'm no stranger to the joys of digging but I did find the awkwardness under the house less than enjoyable. 
> The fact that someone has cut a duct and not closed it off or reconnected it is reprehensible, you must have spent a fortune heating the underneath of the house, no wonder you have had cats in there. All up I would feel like taking a section of duct and inserting it into whoever was responsible for the destruction of the existing ducting.

  I was going to go with the sleeveless overalls and just wear a t-shirt underneath. These will stop my t-shirt riding up and dirt getting in my pants hopefully!  :Biggrin:  
The worst duct isn't cut per se but the hole in it is massive and hanging on by a thread. These people must have liked the cold because the heating is stuffed, there was no roof insulation and the hot water was busted when I moved in! Two of the three have now been fixed, but the biggest issue has been left til last!

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## Grasshopper75

> My point was that the duct spigot on a 23kW is 12" and then add insulation and your clearance between the concrete and house does not appear to be that. There is a chance that this has been jammed through that gap if the concrete was not cut back. Restriction in air right there at the start.

  I took the covers off the heater and the ducting going under the house is not too restricted. There is about 15" clearance from the ground to bearer and whilst it could be better (if room permitted) it certainly isn't crushed to squeeze it through the gap.

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## Grasshopper75

Well I have had some success. I made it under the house, dug a channel and observed some more of the ducting. The first lot of pictures I posted I can now say are the return air, it's shredded, crushed and needs replacing. It also crosses over one of my other ducts restricting the airflow. I'm going to need to draw out a plan of how to run the ducts to ensure I know where I need to dig the channels and to also prevent the crossovers. On the plus side I now think the job is doable but it's going to be a hell of a lot of hard work digging out the soil. I have loads more to do and am going to need to rip out the old stuff in order to reach the far side of the house and start digging, clearing and replacing as I work backwards. 
Since I am doing all the digging, I am now thinking of just replacing the ducting myself to save some coin. One thing I will need done though is a new return air.  
Krico any idea on the cost of a return air? I'm told I need one 800 x 600 in size and most likely boxed out in the cupboard.

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## krico

Are you going to do the RA yourself? Easy to do, a grill will cost anywhere from $30 up to about $150 (plastic vs metal). Just need to make sure you have the clearance underneath to bring it up into the cupboard. Elbow or joiner to mount it through the floor too and that can range from $10 to about $50 (joiner vs elbow). Add to that a few tubes of gap filler to seal all gaps as this void needs to be essentially sealed like duct. I get our boards done at the local kitchen place as I get the edges banded to give a good look, using melamine.  
Should be easy to do with some basic skills needed.  
Krico

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## Grasshopper75

This weekend will be spent digging under the house again. I've made it  as far as the old return air and am hoping to get to the otherside of  the house by the end of the weekend. Still not entirely sure how far I  am going to get but I have put together a design with assistance from  the local duct supplier.  
At this stage I only intend on  replacing the ducting at the front of the house but I will see what the  situation is once I get a good view of all ducts. 
Krico please let me know what you think of this design.

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## krico

> This weekend will be spent digging under the house again. I've made it  as far as the old return air and am hoping to get to the otherside of  the house by the end of the weekend. Still not entirely sure how far I  am going to get but I have put together a design with assistance from  the local duct supplier.  
> At this stage I only intend on  replacing the ducting at the front of the house but I will see what the  situation is once I get a good view of all ducts. 
> Krico please let me know what you think of this design.

   Firstly, is this the current design and are all your outlets 6".                                                                                                                                                
I think your design is OK. The only thing I would suggest is that you try and get more of the bigger size duct through and go smaller runs on the 6". The front two rooms for example. If you can get the 8/6/6 BTO closer, you may be able to split a bag of 6" duct (6mtr) and go half/half on to these two outlets. Sometimes it can be hard to do this with what boot is in there. Are they all side boots (the outlet is on the 300mm side) or do you have end boots too (the outlet is on the 100mm side)? This can make you think a little more about where to run the duct. The same with the hallway outlet and the second room on the right, make the 8" longer and move the BTO closer and potentially you could do the same, split a bag of 6" to each of these outlets. I would also suggest that any straight through on a BTO goes to the longest outlet. For example, the front two rooms if you ducted it exactly like this, the straight through should go to the right hand room because it is a longer run. The minimum length of duct to an outlet should be 3mtrs. This helps with noise reduction. Even if you have to loop it around a bit to make it fit. The same with the rest of the ducting, try and get your 14, 12 and 10" runs a decent length. The only issue I see is that if you wanted to add zoning later, it may be a bit fiddly to add and get some decent zones. And where is your thermostat currently located? And I just read back through the thread and noticed that the crushed duct is your current RA. You probably need to check a few things to make sure you haven't sucked a big pile of doodah inside your heater. The outside panel of your heater is removable and has two/three screws on it. The panel opposite the duct out/inlets. Remove this panel and under that there will be two other panels to be removed, a couple of screws in each. Take these off and check your fan barrel and heat exchanger area for any insulation, ducting etc that may have been sucked through. Will only take a few minutes but worth it I think. Turn the gas off and pull the plug before opening it up.

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## Grasshopper75

Hi Krico, 
Thanks once again for your reply. I really appreciate your help. 
I really have no idea what the setup is like at the moment as I have only made it to the old return air by the front door. So far I have removed the crushed ductwork from under bedroom 1 for the old return air and the 6" duct for bedroom 1. The goal this weekend is to reach the other side of the house as the lounge room duct is completely stuffed. I can see a BTO off to the front two rooms but other than that I haven't seen much more at this stage. The plan I have put up is what the heating place suggested (different mob to who installed my heater). They too provided info about the runs like you, it's just my drawing didn't fully reflect what I was told so I updated this to better reflect yours and their recommendations. FYI, I have the Brivis HX23-XA, supposedly this is better for me.  :2thumbsup:  
My thermostat is located opposite the duct in the entry hallway. Boots are 300mm, I assume you mean the size of the vent on the floor? 
Can I go from 12/8/6 or must I go 12/10/8/6? 
With regards to zoning, I was considering putting them in but just not certain on how I should set them up? Front & rear of house? 3 zones? Any suggestions? 
Finally, the two options I looking at for the new return air is the laundry (as pictured) or the bottom right corner of the walk-in robe (near dining and entry hallway). The repositioning of the return air will all depend on how much clearance I can make under the house. My current return air is by the front door and only 650x250 in size. What are the implications if I can't move the return air & what size would you suggest for a new return air? The path of the ducting for the old return air is also pictured. 
Thanks again.

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## Moondog55

Is there a consensus on where to put the warm air outlets? I thought that the modern way was to have the heat outlets away from the windows.

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## krico

> Hi Krico, 
> Thanks once again for your reply. I really appreciate your help. 
> I really have no idea what the setup is like at the moment as I have only made it to the old return air by the front door. So far I have removed the crushed ductwork from under bedroom 1 for the old return air and the 6" duct for bedroom 1. The goal this weekend is to reach the other side of the house as the lounge room duct is completely stuffed. I can see a BTO off to the front two rooms but other than that I haven't seen much more at this stage. The plan I have put up is what the heating place suggested (different mob to who installed my heater). They too provided info about the runs like you, it's just my drawing didn't fully reflect what I was told so I updated this to better reflect yours and their recommendations. FYI, I have the Brivis HX23-XA, supposedly this is better for me.  
> My thermostat is located opposite the duct in the entry hallway. Boots are 300mm, I assume you mean the size of the vent on the floor? 
> Can I go from 12/8/6 or must I go 12/10/8/6? 
> With regards to zoning, I was considering putting them in but just not certain on how I should set them up? Front & rear of house? 3 zones? Any suggestions? 
> Finally, the two options I looking at for the new return air is the laundry (as pictured) or the bottom right corner of the walk-in robe (near dining and entry hallway). The repositioning of the return air will all depend on how much clearance I can make under the house. My current return air is by the front door and only 650x250 in size. What are the implications if I can't move the return air & what size would you suggest for a new return air? The path of the ducting for the old return air is also pictured. 
> Thanks again.

  The XA means you have an extra air model. From memory, about another 100 L/s airflow which is always good. Means your take-off spigots on the unit are 14" too. I would personally move your thermostat from its current location as you are probably getting false readings where it is. With it being close to the outlet like that, it is going to detect the heat from that and not actually heat the rest of the house to the desired temperature. If you can (depends on furniture and underneath etc) is to put the RA in the bottom left hand corner of your robe. This means that you could swing your supply duct around the other side of it and not have to cross it over. You could go bottom right hand side too and it would just mean a slightly longer run for the supply. This is also where I would move the thermostat to. Easy to do if you are cutting through the floor anyway. You could go 12/8/6 if you want but the only time you would do that is if you have a very long run of 12" (more than one length) and want to force some more air out of these outlets. I think with what the plan shows, you are probably better off stepping down normally. As to zones, it can be hard to know where to zone without talking to a customer about how they "live" in their house. I guess the first rule is that you don't want to be heating areas you don't want to. Now with your house plan, you have a lounge down the front mixed into bedrooms which makes it a little harder. But if you don't use the lounge much, zone it with the bedrooms. Same down the back where you have an outlet in the family running with one to the bathroom. You could also have it exactly as it is right now, and place dampers for example, on all the bedrooms and chain them together. It just means having to buy more dampers. Or you need to zone as best as you can with the duct plan. You can either run them from your controller, two off the main board and three with the purchase of another board to go on the heater. Or you can run as many as you want (240v) and control them via a normal light switch mechanism. With it being an XA I would go for a 1200/400 RA. This will quieten it down a bit. If you can move it, I definitely would. Sorry for the long paragraph, my enter key does not work on this forum. Need to look at another browser I think. Krico

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## Grasshopper75

Hi Krico, 
I think a RA of 1200x400 is out of the question. If I am to move the RA to the robe then I am losing robe space which is not pleasing my wife at all.  :Eek:  I think the largest I could do is 800x600. Just to clarify the sizing, is that the box, the grill or both do you mean? The entry hallway cupboard is also a possibilty however again we would like to keep the space and it would have to be a smaller RA. 
I have updated the floorplan once again, adding cupboards, existing ductwork and new proposed ductwork. Any existing ductwork where I am yet to gain access is unconfirmed. As you can see I have a LONG way to go and it may prove too difficult to even get to the rear of the house. 
So far I have removed 1.5 trailer loads of dirt and have plenty more to go so it is going to take me a few more weekends yet to get the front of the house completed. As I've said previously, I think the rear of the house has better access although unfortunately I need to crawl from the front of the house to get there. 
I think you make a good point about moving the thermostat and I will try and do this. 
I have also added my proposed zones in two versions (see 2 attachments). I'm not sure if this would work but if I were to do the zoning, this is how I would most likely want it done. 
Let me know your thoughts. 
Thanks.

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## krico

> Hi Krico, 
> I think a RA of 1200x400 is out of the question. If I am to move the RA to the robe then I am losing robe space which is not pleasing my wife at all.  I think the largest I could do is 800x600. Just to clarify the sizing, is that the box, the grill or both do you mean? The entry hallway cupboard is also a possibilty however again we would like to keep the space and it would have to be a smaller RA. 
> I have updated the floorplan once again, adding cupboards, existing ductwork and new proposed ductwork. Any existing ductwork where I am yet to gain access is unconfirmed. As you can see I have a LONG way to go and it may prove too difficult to even get to the rear of the house. 
> So far I have removed 1.5 trailer loads of dirt and have plenty more to go so it is going to take me a few more weekends yet to get the front of the house completed. As I've said previously, I think the rear of the house has better access although unfortunately I need to crawl from the front of the house to get there. 
> I think you make a good point about moving the thermostat and I will try and do this. 
> I have also added my proposed zones in two versions (see 2 attachments). I'm not sure if this would work but if I were to do the zoning, this is how I would most likely want it done. 
> Let me know your thoughts. 
> Thanks.

   1200x400 and 800x600 is the same surface area anyway so I guess it now depends on your stud spacings in the wall. I only use the 1200x400 as you are guaranteed of it fitting in the majority of circumstances. If you go to 600 wide, and you have 450 stud spacings, it makes it harder. The box does not need to go the whole way but the majority. If I cannot get a box the whole way, I have at times, had to seal the wall cavity above the RA and suck out of the cavity so to speak. It is the surface area of the grill that is going to make the difference. If you went with a 1200 x 400 and made the box about 900mm high in the back, that should be fine. Your second plan for the zoning looks good. Obviously zone 1 will need to be your common zone which will run all the time and then you can isolate the other two zones. Your plan is looking good and I hope that you can get the job done.

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## Grasshopper75

So after another day of solid digging, I finally made it to the lounge room vent. It took me about 4 hours to move 1.5m but I made it and now have plenty of room to run a new duct. I also made it to the entry hallway vent & thermostat. It's getting incredibly difficult to dig out the dirt and reaching the vent of bedroom 2 is looking to be an impossible task as it is about 5m away from where I reached so far. I have disconnected the ducting for the hallway & bedroom 2 so that it can be re-used if I have to. I was also shocked to find that I still have at least 4m of digging to reach the rear of the house (the clearance is not where I expected) so I can inspect the return air and to see where repositioning is going to be feasible.  
I found two cables running up into the wall (from the subfloor) where the thermostat is. The white cable I know runs back to the heater although there appears to be a grey electrical cable also. I'm not sure if this is something that was left behind from the old system or whether it is 240V? Can anyone confirm what power the NC-3 controller uses? I also can't figure out how to get the controller off the wall to check the wiring from the controller. Can anyone provide instructions? 
Thanks.

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## krico

> So after another day of solid digging, I finally made it to the lounge room vent. It took me about 4 hours to move 1.5m but I made it and now have plenty of room to run a new duct. I also made it to the entry hallway vent & thermostat. It's getting incredibly difficult to dig out the dirt and reaching the vent of bedroom 2 is looking to be an impossible task as it is about 5m away from where I reached so far. I have disconnected the ducting for the hallway & bedroom 2 so that it can be re-used if I have to. I was also shocked to find that I still have at least 4m of digging to reach the rear of the house (the clearance is not where I expected) so I can inspect the return air and to see where repositioning is going to be feasible.  
> I found two cables running up into the wall (from the subfloor) where the thermostat is. The white cable I know runs back to the heater although there appears to be a grey electrical cable also. I'm not sure if this is something that was left behind from the old system or whether it is 240V? Can anyone confirm what power the NC-3 controller uses? I also can't figure out how to get the controller off the wall to check the wiring from the controller. Can anyone provide instructions? 
> Thanks.

  The NC3 only uses a Figure 8 or Twin to the controller. Not sure what your grey cable is. Was your old thermostat located here?  
To remove the controller, use a little flat blade screwdriver on each side where he locking lugs are and the front will pop off. Sometimes you can also just grasp the face firmly and pull with a slight tendency to one side and it will come away. This only works if the backing plate has been firmly attached to the wall. Make sure you have the heater off before disconnecting the controller.  
With the wiring you will have four terminals, and the Fig 8 will either be in the top two or bottom two. Polarity does not matter as it self regulates.  
And Firefox has fixed my enter key problem.  
Krico

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## Grasshopper75

> The NC3 only uses a Figure 8 or Twin to the controller. Not sure what your grey cable is. Was your old thermostat located here?  
> To remove the controller, use a little flat blade screwdriver on each side where he locking lugs are and the front will pop off. Sometimes you can also just grasp the face firmly and pull with a slight tendency to one side and it will come away. This only works if the backing plate has been firmly attached to the wall. Make sure you have the heater off before disconnecting the controller.  
> With the wiring you will have four terminals, and the Fig 8 will either be in the top two or bottom two. Polarity does not matter as it self regulates.  
> And Firefox has fixed my enter key problem.  
> Krico

  Thanks once again Krico. 
Yes my previous thermostat was located where the NC3 is now. The eletrical cable appears to come from the opposite direction to the heater so I really have no idea what it might be. The previous controller was one of these Brivis - HE 5/7 Programmable wall control 
Speaking of thermostats & controllers, I like the NC3 controller however if I go with some additional zones I would still like to be able to programme when the zones are on/off. I know the NC3 cannot do this, but are there any controllers available that have programmable zoning?

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## krico

> Thanks once again Krico. 
> Yes my previous thermostat was located where the NC3 is now. The eletrical cable appears to come from the opposite direction to the heater so I really have no idea what it might be. The previous controller was one of these Brivis - HE 5/7 Programmable wall control 
> Speaking of thermostats & controllers, I like the NC3 controller however if I go with some additional zones I would still like to be able to programme when the zones are on/off. I know the NC3 cannot do this, but are there any controllers available that have programmable zoning?

  Is that cable running towards where the heater used to be. The cable for your old thermostat actually looks like grey flex (like an extension lead) and this could be it? 
You can actually program the zones with the time programming on the NC3. When you are setting the programming up, it will actually give you the option for the zone/s to be on or off. So for example, you want your bedrooms to come on at 6:00pm, select the bedroom zone when setting this up and it will automatically come on when that time period starts.  
Krico

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## Grasshopper75

> Is that cable running towards where the heater used to be. The cable for your old thermostat actually looks like grey flex (like an extension lead) and this could be it? 
> You can actually program the zones with the time programming on the NC3. When you are setting the programming up, it will actually give you the option for the zone/s to be on or off. So for example, you want your bedrooms to come on at 6:00pm, select the bedroom zone when setting this up and it will automatically come on when that time period starts.  
> Krico

  Yes it looks like a grey extension lead! I will need to trace where it goes as I cannot see why anything else would be running into the wall at this point.  
Fantastic info about the NC3 too. I thought I had to manually select the zones so this is exactly what I am after and is pushing me more towards putting the zones in. Is the zoning something I can do myself? Looking at Google images, the zone dampers just look like a metal duct joiner? Easy to wire myself? 
My biggest issues with doing it all myself is still the access restrictions. Whilst I have shovelled alot of dirt, getting the ducting in and zone dampers in is still going to be a challenge, especially through the man hole and to the rear of the house. If I have to get access where the heater is then I am going to have to call in the professionals to disconnect the heater. If I can get everything in and the dampers are easy enough to wire than I will certainly be doing it myself. 
Krico I definitely owe you a case of beer for all your help!! I really thought this job was beyond me but with the info you have provided you have really given me hope of getting this completed myself. Thanks again!  :Cheers2:

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## krico

> Yes it looks like a grey extension lead! I will need to trace where it goes as I cannot see why anything else would be running into the wall at this point.  
> Fantastic info about the NC3 too. I thought I had to manually select the zones so this is exactly what I am after and is pushing me more towards putting the zones in. Is the zoning something I can do myself? Looking at Google images, the zone dampers just look like a metal duct joiner? Easy to wire myself? 
> My biggest issues with doing it all myself is still the access restrictions. Whilst I have shovelled alot of dirt, getting the ducting in and zone dampers in is still going to be a challenge, especially through the man hole and to the rear of the house. If I have to get access where the heater is then I am going to have to call in the professionals to disconnect the heater. If I can get everything in and the dampers are easy enough to wire than I will certainly be doing it myself. 
> Krico I definitely owe you a case of beer for all your help!! I really thought this job was beyond me but with the info you have provided you have really given me hope of getting this completed myself. Thanks again!

  No problems at all. Dampers are easy to install within the ducting and are essentially as you described. You can get them in metal or plastic and you will need 24V ones to suit your heater. A lot of them these days are using essentially telephone cables to join them to the heater and they can also be daisy chained. So it is as easy as installing in the duct line and then the wiring. I suggest that you buy a drive open drive shut damper. Use good quality duct tape and make sure the insulation is dragged up as far over the damper as you can. A lot of dampers are not insulated very well these days.  
Krico

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## Grasshopper75

So I finally got my heater disconnected today however I was a little disappointed to what I found. Unfortunately the easy access I was hoping for was simply not there. I would have to rip out all the ducting to even have a chance of getting in so it's back to the digging for me. I think I need to make a call very soon on whether I persist with the digging to reach the rear of the house or whether I simply replace the ducting I have removed and restore it to its original setup. I would much prefer to correct the wrongs of this setup but the digging and removal of dirt is getting much harder now as I move further through the house and I need to get something in place before winter really hits. So I will press on this weekend and will see how far I get. Wish me luck!

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## Grasshopper75

Just when I thought I was almost there... I have reached the rear of the house but have found that the access is not as good as I had thought. The good news is that the ducting appears to be in good order and does not appear to need any repairs. I have decided to abandon the option of zoning as it is just going to be too difficult to implement due to the access restrictions. I have purchased most of the new ducting and insulated BTOs although I am still investigating the possibilities of moving the return air and the thermostat. 
A message for you Krico, the return air duct off the heater is 14" however it is then reduced to 12" almost immediately once under the floor. I spoke to the duct supplier and he has said that I need to make it 14" all the way as using 12" may cause the ducting to suck shut, effectively causing poor airflow and fan issues in the heater. Is this a likely scenario? The existing ducting was 12" although this was the way it was previous to my new heater being installed. I would like to make it 14" however as usual, clearance under the floor may be an issue. There is a concrete slab under the kitchen so digging it out might not be an option.

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## krico

> Just when I thought I was almost there... I have reached the rear of the house but have found that the access is not as good as I had thought. The good news is that the ducting appears to be in good order and does not appear to need any repairs. I have decided to abandon the option of zoning as it is just going to be too difficult to implement due to the access restrictions. I have purchased most of the new ducting and insulated BTOs although I am still investigating the possibilities of moving the return air and the thermostat. 
> A message for you Krico, the return air duct off the heater is 14" however it is then reduced to 12" almost immediately once under the floor. I spoke to the duct supplier and he has said that I need to make it 14" all the way as using 12" may cause the ducting to suck shut, effectively causing poor airflow and fan issues in the heater. Is this a likely scenario? The existing ducting was 12" although this was the way it was previous to my new heater being installed. I would like to make it 14" however as usual, clearance under the floor may be an issue. There is a concrete slab under the kitchen so digging it out might not be an option.

  It would be better to run 14 all the way if you can manage it. What he is saying is true to a point, but I dont think it is too much to worry about if you cannot get it done. I have had to do this at times myself when there was just no other option. Obviously after you have installed this, you will need to adjust your fan speed so you may find you dont need to run it flat out so the air flow may not be an issue.

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## Grasshopper75

> It would be better to run 14 all the way if you can manage it. What he is saying is true to a point, but I dont think it is too much to worry about if you cannot get it done. I have had to do this at times myself when there was just no other option. Obviously after you have installed this, you will need to adjust your fan speed so you may find you dont need to run it flat out so the air flow may not be an issue.

  Another two days of solid digging and I'm on the home stretch. I've decided to run 14" the entire way back to the heater for the new return air however it now means I need to dig a deeper channel back to the heater. I also discovered that the return air inlet is on the other side of the heater which means I need to crossover the ducts. This now means I need to break up the concrete slab which is under the house where the ducts enter and then dig a deep enough channel to allow the two ducts to crossover each other. Just another challenge! 
So effectively, I will have 14" for the entire R/A however for the heating it will go from 14" to 12" rather quickly as I will be connecting it to the existing ductwork.  
Krico, does this sound OK?

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## krico

It is a hard call as I reckon that you wont need to have the fan speed ramped up a lot due to the duct sizing. You may get away with a 12" duct for the RA but, in the long run, would be better for it. As to the supply, stick with what is there and see how it goes with all the outlets actually connected to the house and the RA hooked up too. I think it will be enough to get a good cycle of air.  
Just so you know, you can swap the position of the supply and return air on these heaters by turning the heater 180degrees. The side panel pulls off and simply reattaches the other side. In your case this will not work as your flue will end up next to your kitchen door.  :Annoyed:  So back on the shovel it is?

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## Grasshopper75

So I am 6ft away from finally finishing this digging. So far it has taken me 12 weeks digging at least one day every weekend and I have filled 8 trailers (6x4) clearing all the dirt and am now on the home stretch. The concrete slab under my kitchen was impossible to break in such a confined space so it was lucky that I managed to find a way around it by running the RA duct around and under the supply duct further towards the back of the house. It now means I will have 14" RA duct the whole run and my supply will no longer be crushed and squeezed under the bearers. 
Due to the size of the RA box I decided to move the new return air to the laundry cupboard. It's a better spot for it and makes my wife happy knowing that I'm not stealing her wardrobe space. I am also going to move the thermostat to the back of the toilet wall to move it away from the outlet in the hall. 
Now, I have purchased a metal filtered return air grille (Metalflex 950x450mm) and need some advice on how to fix this to the plaster wall? The grille is rather basic, it looks like I simply need to cut a hole and slot it in. My concern is that because the grille has a filter and door that over time the grille will wear away the plaster by opening the door and then become loose. The grille doesn't have any insturctions or points to fix it to anything. The guy at the shop told me I should build a frame? The only thing I can think of is to drill some holes in it and fix it to a nearby stud? Any other suggestions or are there better grilles available?

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## krico

> So I am 6ft away from finally finishing this digging. So far it has taken me 12 weeks digging at least one day every weekend and I have filled 8 trailers (6x4) clearing all the dirt and am now on the home stretch. The concrete slab under my kitchen was impossible to break in such a confined space so it was lucky that I managed to find a way around it by running the RA duct around and under the supply duct further towards the back of the house. It now means I will have 14" RA duct the whole run and my supply will no longer be crushed and squeezed under the bearers. 
> Due to the size of the RA box I decided to move the new return air to the laundry cupboard. It's a better spot for it and makes my wife happy knowing that I'm not stealing her wardrobe space. I am also going to move the thermostat to the back of the toilet wall to move it away from the outlet in the hall. 
> Now, I have purchased a metal filtered return air grille (Metalflex 950x450mm) and need some advice on how to fix this to the plaster wall? The grille is rather basic, it looks like I simply need to cut a hole and slot it in. My concern is that because the grille has a filter and door that over time the grille will wear away the plaster by opening the door and then become loose. The grille doesn't have any insturctions or points to fix it to anything. The guy at the shop told me I should build a frame? The only thing I can think of is to drill some holes in it and fix it to a nearby stud? Any other suggestions or are there better grilles available?

  Nearly there Grasshopper!  
About the RA grill, either make the opening against a stud and screw to that, or back block behind the gyprock and then screw into that. It works like a clamp to squeeze the RA grill frame against the gyprock and keep it secure. If that makes sense? You may need to make a few holes in the frame of the RA but plenty of room in the back part behind the grill etc.

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## Grasshopper75

Last weekend I completed the digging. That is 13 weekends, 8 trailer (6x4) loads of dirt, $560 in tip fees and countless hours of digging done! 
Today I have moved the thermostat which again had its challenges but is exactly where I want it and looking good. 
Tomorrow is cutting through the floor of the laundry cupboard for the new return air and starting to fit the new ducts. Here's hoping I can get all the ducts completed tomorrow (although I doubt it)!

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## GraemeCook

Good Morning Grasshopper 
Just stumbled on your thread and progress report.  Seems to be going well.   Krico has been a really good friend and advisor.   Its guys like him that make this Forum so helpful.  When it's finished, you might owe him a beer! 
A few years ago a friend and I installed n ducted heat pump in a 150 year old house (we are in Hobart) and struck many of the problems you encountered.  For part of the house we had full kneeling headroom, part was crawling room and some of it was wriggle-room only.  Our responses included: - A little late for you, but best for removing dirt was a militiary trenching tool bought from a disposals outlet.Headband lights plus several lights on extension leads were invaluable.   Shadows are an issue.We got filthy from crawling in 100+years of accumulated dust;  a neighbour was recarpeting so we used his old carpet to carpet the crawl space.  Brilliant.   Used carpet is real cheap, sometimes free.To keep the duct off the ground we got a roll of upholsterers webbing and stapled the duct up to every second joist.Think very carefully about the order in which you install the ducts.   Some ducts may impede access to others.  Do those ones last!Where the duct runs in the same direction as the joists, then you get more clearance if you install it between the joists rather than under them.Be really, really careful with every duct junction and use lots of duct tape to ensure an absolutely air-tight join.  Many systems lose 20 or 30% efficiency due to air leaks.  
While you're enjoying being under the floor it might also be worth thinking about insulating the floor.   Sisalation stapled to the underside of the joists is probably the easiest and most cost effective. Adding batts between the joists would be even better.  A reduction in your heating costs of up to 20% should be achievable.   
Fair Winds 
Graeme

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## Grasshopper75

> Good Morning Grasshopper 
> Just stumbled on your thread and progress report.  Seems to be going well.   Krico has been a really good friend and advisor.   Its guys like him that make this Forum so helpful.  When it's finished, you might owe him a beer! 
> A few years ago a friend and I installed n ducted heat pump in a 150 year old house (we are in Hobart) and struck many of the problems you encountered.  For part of the house we had full kneeling headroom, part was crawling room and some of it was wriggle-room only.  Our responses included: - A little late for you, but best for removing dirt was a militiary trenching tool bought from a disposals outlet.Headband lights plus several lights on extension leads were invaluable.   Shadows are an issue.We got filthy from crawling in 100+years of accumulated dust;  a neighbour was recarpeting so we used his old carpet to carpet the crawl space.  Brilliant.   Used carpet is real cheap, sometimes free.To keep the duct off the ground we got a roll of upholsterers webbing and stapled the duct up to every second joist.Think very carefully about the order in which you install the ducts.   Some ducts may impede access to others.  Do those ones last!Where the duct runs in the same direction as the joists, then you get more clearance if you install it between the joists rather than under them.Be really, really careful with every duct junction and use lots of duct tape to ensure an absolutely air-tight join.  Many systems lose 20 or 30% efficiency due to air leaks.  
> While you're enjoying being under the floor it might also be worth thinking about insulating the floor.   Sisalation stapled to the underside of the joists is probably the easiest and most cost effective. Adding batts between the joists would be even better.  A reduction in your heating costs of up to 20% should be achievable.   
> Fair Winds 
> Graeme

  Too right Graeme, I definitely owe Krico a few beers. Without his assistance I don't think I would have had the confidence in doing this myself. The good news is that the ducting is now installed. I only have a small amount of ducting to run back to the heater which I plan to do by the weekend. 
It's never ending with problems though, I have now run the RA duct up into the laundry cupboard and have now realised that there is a stud right in the middle of where I want to put the grill in the wall. I'm not sure if anyone has advice on this one but I do know a friend of a friend who is a chippy so I might have to ask them what I need to do. 
Once the last piece of ducting is done, the RA grill installed, it's simply a matter of boxing in the RA and getting a licensed gas plumber to reconnect the heater. I'm hoping I can get it all done within the next week. I've already had one electricity bill, which mind you included part of summer, but it was $200 higher than normal because of having to run the reverse-cycle!! I need to get this job completed ASAP! 
Thanks once again Krico and to all those that contribute on this forum, it's people like you that help the not so knowledgeable people like me  :Biggrin:  get stuff done around the house.

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## Grasshopper75

It's finally over!  
3 weeks ago I finished building the return air box in the laundry cupboard. I installed the new filtered return air grill and called the gas plumber to come and reconnect the heater. The only thing left to do now is plug up the hole in the floor where my old return air used to be. 
The house is now toasty warm and takes minutes rather than hours to heat up to the desired temperature. I've also noticed the heater does not run anywhere near as much as it had to before which will hopefully reduce the electricity and gas bills. 
As I have said before, a huge thank you to Krico and those others that contributed to this thread to help me in getting this done. 
Thanks again.

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## krico

> It's finally over!  
> 3 weeks ago I finished building the return air box in the laundry cupboard. I installed the new filtered return air grill and called the gas plumber to come and reconnect the heater. The only thing left to do now is plug up the hole in the floor where my old return air used to be. 
> The house is now toasty warm and takes minutes rather than hours to heat up to the desired temperature. I've also noticed the heater does not run anywhere near as much as it had to before which will hopefully reduce the electricity and gas bills. 
> As I have said before, a huge thank you to Krico and those others that contributed to this thread to help me in getting this done. 
> Thanks again.

  Grasshopper,  
Well done. I hope you are happy with the outcome. It is always good to sit back after a job like this especially when the temperatures are through the floor like they are today, and enjoy the warmth of your achievement. Plus, if the family is happy and warm, even better.  
You should definitely see a difference in your gas bill and to see the heater cycling like it is, is a good sign that you are reaching your temperature correctly and the heater will only work when needed and unlike before, where it was probably running 100% all the time.  
Well done on a huge job for someone who has not done this before.  
Krico

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