# Forum Home Renovation Heating & Cooling  Heat transfer system - my take

## Tarasa

Here's my current project, to get some heat from one end of the house and into the kids bedrooms.  
Parts -
Inline fan, 250 dia, allegedly 650 cfm
2 x 6m 250 dia insulated flexible duct
4 x 6m 150 dia flexible duct
1 x 4 way splitter, 250 dia in, 150 dia out
1 x 300x300 return air grille
4 x 230x230 supply air grilles
Duct tape, apparently you can never have enough duct tape!   Sorry for the dark pics, it's a bit dark in the roof  space.   Vents  for the roof      Bits and  pieces, fan, splitter and ductwork.     Duct on  splitter     Inline  fan and duct to splitter    How I taped the ducts - start with the inner layer of the duct, tape it to the  housing, I did 3 laps of tape on each layer.     Then tape the outside skin after taping the insulation layer in  place.     Redneck  fan mounts. Figured I would hang it so I don't get vibrations and noise through the roof. The fan is actually very quiet and barely moves on start up. I may make up a mount to hang from the roof but that's not a priority at the moment.     Duct  running in front of TV antenna, the vent needs to go just where the duct ends in the photo. I may have to lift the antenna up if it  interferes, I guess time (and complaints from the kids) will tell.     Next  step - fitting the 4 splitter legs and cutting holes in the roof. Not looking  forward to that part....stay tuned.

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## nww1969

I take it you don't have a waterproof tv antenna?? 
How much did the inline fan cost ?? and how is it controlled?? 240 or 12 volt. 
Thanks Neil.

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## Tarasa

Antenna was in the house when we bought it. And we are not too far from the transmission towers (can see them when standing on the roof) so the signal strength is not a big issue. And the birds can't crap all over it! 
Fan is an ebay one from a hydroponics supplier. (http://cgi.ebay.com.au/EZI-AIR-INLIN...ng_Hydroponics) Or just put inline fan in and see what pops up. It was $80 plus postage. It's 240V and has a plug. I will have a switch in our hallway and outlet put in the roof to control the fan. 
The ducts and grilles I got from this place (http://www.polyaire.com.au) Great service and quick delivery (from the Melbourne branch anyway)

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## Smurf

In New Zealand you can get an in-line electric heater as part of these heat transfer kits. So you can use it either just to transfer heat from a wood / gas etc heater or alternatively you can add some extra heat to get the rooms you are moving the heat into warm more quickly. The boost heater can be switched off and the system used as a normal heat transfer system when preferred. 
Anyone know if these are available in Australia? All the suppliers of air transfer kits I've looked at seem not to sell them with supplementary heaters. 
The NZ ones are around 1.5kW to my understanding but there may be other sizes also. Not intended for use as a sole heating system, they are too small for that, but a means to warm the bedrooms etc up more rapidly and to get some heat flowing before the wood heater etc has warmed up. (Yes I do realise that 1.5kW isn't a huge amount of heat - it's a booster).

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## m6sports

Tarasa how much did it end up costing in total ?

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## Tarasa

m6sports - Ducts came in at $350 for the lot delivered to my work. Obviously it will vary depending where you are, what you order etc. Fan was $80 plus delivery. 
Now the point of no return. 
I climbed into the roof space with tape measure and screwdriver in hand and found where the lights entered each room. Found roof beams, battens etc and determined where the duct and vent will fit. I marked the centre of each hole with the screwdriver jammed through the roof. Then into each room and using a cardboard template I marked the spot in the roof where the vent will go. Measured off the cornince to try to get the vent square in the room, geeez it's hard to gauge when there's nothing to line up with. 
Hole cut and the duct was in the right spot!   
The black part of the vent has little tabs on the neck, I bent them out to hold the duct in place.   
Then taped the inner sleeve first, pulled the insulation down and then taped the outer sleeve to the vent top.   
Then the other half of the vent simply clips onto the rest of it. The white tabs on the sides of the vent are spring loaded clamps. Set them in place and simply push the vent into place, the clamps fold over and hold onto the roof.   
Doesn't look too bad.......

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## Tarasa

Well, everything is in place, wired, taped, sucking and blowing as it should. 
Main grille in the family room   
The new heater in the family room, pumps out quite a bit of heat. Anyone want one? I have a spare  :Smilie:    
And the fridge frog confirmed last night that the system actually works. Was 20C in the family room and after having the fan on for an hour, one of the bedrooms was 16C, much nicer than it was previously (forgot to take before measurement, I'll do that and post it up.)   
Noise - there is none. Can't hear any through the supply grille while watching TV or talking etc. Maybe if I get real close and listen hard there may be. Bedrooms are silent also, and you can feel a light breeze coming from each 1/4 of the vent. And the fan is pretty quiet in the roof also, the ductwork kills a lot of the noise. 
Overall I envisaged the airflow would be higher and I would be creating massive drafts in rooms etc. But as the air is split 4 ways, then 4 at the bedroom roof, there is no issue with drafts. 
Thanks for reading  :Smilie:

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## Moondog55

Thanks for the pictures 
Let us know how this goes in the long term if you would please. 
If you were doing it again would you stay with the 250mm duct or go to the bigger 300 duct and a bigger fan?? 
CC and I are still having that "forceful discussion" of the merits of air transfer over ducted heating, and I do want to keep the Coonara for the foreseeable future, and work on improving the efficiency of the wood heater.

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## Smurf

Installed mine yesterday. 250mm fan into 3 rooms, one of which has the vent closed at the moment. 
I hasn't had a real test yet in terms of cold weather, but it's certainly blowing out nice warm air taken from ceiling immediately near the combustion heater. The bedrooms are certainly a lot warmer. 
I suspect that it wouldn't work as well if the combustion heater had its own fan or if I had some other form of heating that doesn't create a hot layer just below the ceiling. But it's working very nicely with the heating I have now. 
Only issue I have is a bit of a rumble that can be heard. I'm going to re do the fan mounting and put some rubber in which hopefully will fix the problem.  :Smilie:

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## Moondog55

It may work better, one of CCs complaints is that the Coonara is too hot, so sucking some of that fan blown heat straight up and then into another room may work well. 
I think that some finite element analysis would be needed to determine the very best placement of inputs and output ducts, is there such a HVAC program??
Otherwise I would be placing the warm air inlets in a corner near an external wall and the inlet duct directly above the wood fire

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## Smurf

> It may work better, one of CCs complaints is that the Coonara is too hot, so sucking some of that fan blown heat straight up and then into another room may work well. 
> I think that some finite element analysis would be needed to determine the very best placement of inputs and output ducts, is there such a HVAC program??
> Otherwise I would be placing the warm air inlets in a corner near an external wall and the inlet duct directly above the wood fire

  Another benefit if removing the "hot layer" just below the ceiling is that I can now run the fire hot enough to heat the whole room, not just the top of it. So there's a benefit in the room the heat is being taken from too. 
As for placement of outlets and the inlet, I put the inlet just beside the heater. I wanted to keep away from the flue for reasons of safety etc since the ducting could possibly move a bit in the roof if a possum gets in etc. Unlikely maybe, but better safe than sorry with things like that. So it's about a metre to the side of the heater. 
Outlets I put above the centre of the built-in cupboards in each bedroom. My thinking being simply that beds and other furniture can be moved, but it is unlikely that anyone would ever put a bed in front of the cupboard. I was thinking that it wouldn't be a good idea to have the outlet above any potential bed location due to draft etc. 
So far, so good... 21.6 degrees in one of the bedrooms right now according to the thermometer. I only turned it on a bit over an hour ago. 
System I have uses 250mm duct for the intake to the fan, and 150mm ducts to each room. Fan uses 95 Watts of electricity, so about 2 cents an hour to run.

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## Moondog55

So you think then that size duct is adequate and no greater benefit going the next size up??

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## Smurf

> So you think then that size duct is adequate and no greater benefit going the next size up??

  I think that would depend on the situation - house size, number of rooms etc. 
In my case I'm simply taking heat from above the slow combustion heater in the dining / kitchen area (25m2) in the middle of the house (open via 2 doors into the lounge) and putting it into the bedrooms at the end of the house. So the distances are small, the grade of the heat is fairly good (ie hot above the heater near the ceiling) and so on. House is about 14sq in total, and I'm not worried about heating the laundry or toilet. 
I suspect that it wouldn't work as well with reverse cycle A/C as the heat source, since that doesn't normally produce 35+ degrees at the ceiling. In that case moving more air might be necessary.  
I've placed the fan unit and layed out the ducts so as to permit the installation of an in-line electric heater in the 250mm duct at a future date if required. These aren't common but they do exist (not cheap though). This idea relates to my concern as to how well the system would work if I change the heat source to reverse cycle A/C in future and there is no longer a high temperature at ceiling level. I'll only add the heater if it turns out to be actually necessary. 
I should get a pretty good idea of performance with a non-wood heat source once we get some milder weather and I can run the electric fan heater (existing) for heat in the evening rather than using the wood fire. I'll keep a very close watch on temps around the house to see how it's going.  
Historically, the electric heater used in mild weather (it's not big enough for mid-Winter) gets the dining room area to 21.5 (what the thermostat is set to) and the bedrooms around 18. So that will be 21.5 degree air going into the heat transfer system rather than 30+ when the combustion heater is running. Will be interesting to see how it goes.

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## Tarasa

> I think that would depend on the situation - house size, number of rooms etc. 
> In my case I'm simply taking heat from above the slow combustion heater in the dining / kitchen area (25m2) in the middle of the house (open via 2 doors into the lounge) and putting it into the bedrooms at the end of the house. So the distances are small, the grade of the heat is fairly good (ie hot above the heater near the ceiling) and so on. House is about 14sq in total, and I'm not worried about heating the laundry or toilet. 
> I suspect that it wouldn't work as well with reverse cycle A/C as the heat source, since that doesn't normally produce 35+ degrees at the ceiling. In that case moving more air might be necessary.  
> I've placed the fan unit and layed out the ducts so as to permit the installation of an in-line electric heater in the 250mm duct at a future date if required. These aren't common but they do exist (not cheap though). This idea relates to my concern as to how well the system would work if I change the heat source to reverse cycle A/C in future and there is no longer a high temperature at ceiling level. I'll only add the heater if it turns out to be actually necessary.
>  .

  I agree, depends what size rooms, what your heat source is, what you want to achieve and at what cost. For our requirements we live primarily in our family room so all we require is to warm the bedrooms in winter above freezing. So far that aim has been achieved. Could we use it to heat the rooms more - no. The air inlet is on the opposite side of the room from the wall heater so we are only moving 20C air (maybe a little higher as it is at roof height) around the house. Moving more air may help warm the rooms but I think to do it properly hottter air has to go in. The idea of an inlet vent above an open fire would work well (as Smurf said) if you had one.  
I'm hoping in summer we can use this system to pull cold air from the airconditioner and waft it around the rest of the house, to take the edge of fthe heat. But we haven't had a summer here yet so I don't know how bad/good the house is. Time will tell.

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## Moondog55

Thanx fellas, helps me in my discussion with "Herself" I am thinking that bigger would be better in this house but it is almost triple the cost to go from 250 to 300mm; we would probably see a noticeable difference as the wood heater can really pump out some heat with the right fuel load, Coonara say a 14 square house with this model, trouble being that the heat gets trapped and will not spread, so air transport has always been im the front of my mind

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## Bloss

Well a nice looking job Tarasa, but -- the pics show what looks to be barely R-2 insulation in that ceiling. If it were me I would have spent around the same amount of money and labour and upped the insulation to at over R-4 by adding R-3.5 or R-4 batts over the top. That would give a major comfort improvement in the whole house. Then any heat transfer system would be more effective too - as there would be reduced heat loss from the rooms. But that's just me . . .

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## GraemeCook

> Well a nice looking job Tarasa, but -- the pics show what looks to be barely R-2 insulation in that ceiling. If it were me I would have spent around the same amount of money and labour and upped the insulation to at over R-4 by adding R-3.5 or R-4 batts over the top. That would give a major comfort improvement in the whole house. Then any heat transfer system would be more effective too - as there would be reduced heat loss from the rooms. *But that's just me* . . .

  
Me, too, Bloss;  good advice again. 
Cheers 
Graeme

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## Tarasa

Thanks Bloss for the comments, yes, updating the roof insulation is on my list of things to do. I needed to do this first, the front half of the house wouldn't warm itself up with extra insulation, so the air shifting had more of a priority.

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## Moondog55

Keep us posted on things, I am very interested in this approach and want to know how it performs in the summer if you use the airconditioner on cooling cycle.

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