# Forum Home Renovation Solar Electrical Systems  Solar vs LPG Gas vs Heatpump

## jammy1

Hi,  I[m pretty new to this site & wonder if someone out there can help me out?  I'm having a house built, in Cairns, North QLD & can't decide which hot water system to use.  The house builder automatically puts Gas Hot Water, it will need bottles as there is not mains gas.  I would really like Solar, as I'm really trying to reduce my electric bill.  My builder has now told me about a Heat pump.  I'm totally confused, can anyone tell me what is the cheapest to run in the long term, thanks  :2thumbsup:

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## GraemeCook

Good Morning Jammy 
Gas systems are the cheapest to install, but bottled gas usually costs six or seven times more than town gas and two or three times more than electricity,  meaning that this option would be expensive to run. 
In most areas, solar will give you about 75% of your hot water, and will have to be boosted with gas or electricity for the other 25%.   Even in the tropics it is not always sunny - for example, in February Hobart receives more sunshine than Darwin - longer days and no wet season! 
Properly sized heat pump hot water will give you 100% of your hot water at one-third the operating cost of standard electrical system. 
You just have to balance the capital costs against the operating costs, and do the maths.   Most families, assuming you do not have six teenage daughters, will use around 3,000 kilowatt hours for water heating per annum. 
Cheers 
Graeme

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## jammy1

Hi Graeme, 
Thanks for the info, you confirmed what I already thought.  I think I'll go down the solar route.  
Jammy

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## Haveago1

I had a heat pump installed on Wednesday and am having it replaced with a 'normal' tank on Monday - neighbour was banging on my door at 6am the morning after it was installed complaining about the noise. 
I don't think it was that bad (just a fan noise similar to an A/C unit) but had the Rheem tech out to confirm there was nothing wrong with it to keep the peace momentarily. On the quiet he commented that Heat Pumps are expensive to maintain and replace parts on as it requires a refrigeration technician to do anything on them as they are computerised and have a sealed refrigeration unit.....even a 'minor' issue is likely to cost $500-$600 to reslove once the warranty runs out...something to think about

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## Smurf

Rheem heat pumps in particular seem to be associated with rather a lot of horror stories. Dux cop plenty of criticism too. 
My experience is that of those who have heat pumps and are happy with them, they usually seem to have (listed in no particular order) Stiebel Eltron, Siddons Solarstream or Quantum units (Quantum are a bit noisy, but otherwise a solid performer). 
The Siddons I have sounds the same as a reverse cycle A/C. Given that most people have one of those running all night to keep the house warm in Winter, I can't see my water heater causing any issues with noise. The neighbours probably don't even realise it's not just a reverse cycle A/C since that's what it looks and sounds like. But I carefully located it away from bedroom windows (either mine or neighbours) just to be sure.The only time I hear it is in the toilet, and even then it's not exactly noisy. 
Different system for different situations. Heat pumps aren't for everyone that is for sure. But neither is solar - which is best is very site specific.

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## Bloss

Worth noting that you are comparing quite different systems and the choice will be made on your evaluation of which is most important to you and you needs.  
In Qld where the OP is solar is a very good choice and the most sustainable, environmentally friendly and cheapest over lifetime - but higher capital cost. Correctly sized and with sufficient storage they can work even without boosting although most will have a booster as 'insurance'. 
A heat pump is simply and energy efficiency gain if you are grid connected - they are still using electricity which is still coal generated (with a little gas). If you are generating your own solar and/or wind power off-grid then they might be an OK choice, but will still use a heap of power compared to a solar system. They are very effective in Qld and a good lifetime cost, but offer a conservation approach to the environment - not a sustainability approach. That is they are better than gas and a lot better than regular electric HWSs, but not as good as solar. 
Instantaneous gas are also very efficient, but are a conservation approach - it is still fossil fuel. So if you are looking short term and cheapest capital cost then standard electric or gas storage HWS are what you would choose - I reckon that will be the most expensive decision over the life of those systems though. 
If you want to help the environment a bit, but still face increasing power bills and a higher cost than solar over the life of the system then the heat pump is the go. 
If you can afford the capital cost and want to have the lowest lifetime cost and make the biggest impact on the environment then solar HWS is the only choice right now. 
There are some other options that are uncommon in Australia so far that will give a different set of choices (like ground exchange geothermal, phase-change heating and cooling systems, more efficient 'engines' using natural gas fuel cells (such as this Aussie product Ceramic Fuel Cells Limited :: BlueGen). Their suitability and performance will vary on the region and your local weather conditions, but the above is how it stands today. 
If you are handy there are some retrofit solar systems using reasonable quality evacuated tubes (designed in Germany made in China - search ebay) that can utilise former electric storage HWS tanks of 350-400l (so electricity element acts as the booster) and they will come in way lower than the name brand systems even without government subsidies. That's the path I am now taking at home having done a couple with friends. I am using 2 400l tanks with the aim in chilly old ACT of not having to use boost even in winter. If I can find time (but can't promise!) I will try to take pics and do up a guide as I go.

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## Buzzman

+1 
An issue that Bloss didn't mention is that Heat Pump HWS are supposed to be fitted to normal Peak supply, rather than Off Peak, so they can better take advantage of the warmth of the day to heat the water in the tank, and so the noise of the fan running doesn't offend neighbours at night! 
The flipside of this requirement is that they are on Peak Tariff, so even though they may use 1/2 to 2/3 less power than normal OP HWS, the power costs more than twice as much. 
So NOT the most cost-effective option long term. 
But if your site is overhung with trees, it may be the only option that will work.

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## Smurf

> +1 
> An issue that Bloss didn't mention is that Heat Pump HWS are supposed to be fitted to normal Peak supply, rather than Off Peak, so they can better take advantage of the warmth of the day to heat the water in the tank, and so the noise of the fan running doesn't offend neighbours at night! 
> The flipside of this requirement is that they are on Peak Tariff, so even though they may use 1/2 to 2/3 less power than normal OP HWS, the power costs more than twice as much. 
> So NOT the most cost-effective option long term. 
> But if your site is overhung with trees, it may be the only option that will work.

  Agreed in general. 
My overall experience with heat pumps, both water heating and reverse cycle A/C used primarily (or as is often the case in Tassie, only) for heating is as follows: 
1. There are a lot of duds to choose from and a few good ones. 
2. The biggest selling brands are, in general, the duds. 
Now, as an electrician Smurf likes getting things like this right. I put more research into the water heater than most people would into buying a new car... 
The Siddons runs fine on off-peak, indeed it specifically intended for connection to off-peak. It has saved 65% on energy costs over 12 months in Tasmania (as measured by the electricity meter). So, the same off-peak tariff but using 65% less of it. That's a saving... 
The noise is no worse than the reverse cycle A/C that most people have running all night in winter anyway, so it's not something that anyone is likely to notice (though they might if you live somewhere where running revese cycle A/C all night isn't common). 
For my specific situation, it would be hard to beat the performance of the heat pump. A 65% saving and still using cheap power. Nobody will guarantee that for solar in Tassie - it's different in Qld etc of course with more sun (hopefully - Qld could do with a bit of fine weather at the moment...) 
As I said though, heat pumps are one of those things where you need to be very careful what brand you buy. As a general tip, if it's got a booster element then stay well clear of it. The only reason for fitting such an element is either (1) because you really do live somewhere that sees temps below zero all day in Winter or (2) the heat pump doesn't work properly. 
In the context of the Australian market, it's unlikely that any manufacturer would fit booster elements to every system just in case someone up in the mountains decides to buy one. It's not as though Holden supplies a set of snow chains with every car they make or every home is equipped with a fire fighting pump and hoses. In practice, these things are optional and purchased only by those who actually need them. The heat pump manufacturers just fit boosters to hide the fact that the heat pump doesn't actually work properly in the first place...

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## m6sports

We had a Rheem heat pump installed close to 2 years ago and have had a couple of problems with it 
First on was a failed LED on the unit  
The other was the water pump failed about a year into having it. The technician said it's a know problem and they are working on fixing the problem  
I've run mine on off peak the whole time and my bill on average has been 1/2 what it was before we had it installed  
As for noise I cant see it being any louder that my AIrcon unit. But my Rheem it the one with the heat pump on the side of the tank not on top. I was told not to get one that is top mounted as they run louder

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## Buzzman

Dunno if it's different down in Tassie, but tweo separate sparkies have told me it is "a requirement" to fit heat pump HWS to Peak rather than Off peak supply. 
Most people don't, and soon find they need to switch from OP1 to OP2  so they get another boost during the day the day, as they are running out of hot water on OP1, not getting ewnough heat into the tank overnight. 
Hadn't heard of the Siddons before, but looks like a good unit.

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## m6sports

> Dunno if it's different down in Tassie, but tweo separate sparkies have told me it is "a requirement" to fit heat pump HWS to Peak rather than Off peak supply. 
> Most people don't, and soon find they need to switch from OP1 to OP2  so they get another boost during the day the day, as they are running out of hot water on OP1, not getting ewnough heat into the tank overnight. 
> Hadn't heard of the Siddons before, but looks like a good unit.

  I'm not sure about tassie but the only time I ran out of hot water was when
The pump died and was only running on the booster element and I'm on off peak

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## Smurf

> Dunno if it's different down in Tassie, but tweo separate sparkies have told me it is "a requirement" to fit heat pump HWS to Peak rather than Off peak supply. 
> Most people don't, and soon find they need to switch from OP1 to OP2 so they get another boost during the day the day, as they are running out of hot water on OP1, not getting ewnough heat into the tank overnight. 
> Hadn't heard of the Siddons before, but looks like a good unit.

  I'm certain that electricity suppliers in Qld will allow heat pumps on the off peak tariffs. Not sure about NSW but I'm pretty sure there's no problem. 
Depending on model, it is the manufacturers themselves that don't like heat pumps going on off-peak, not the electricity suppliers. With a decent quality unit there should be no problem on off-peak 2 (longer hours) and under some circumstances off-peak 1 (shortest hours) would also be an option. 
Bottom line is if you end up having to run it on peak tariff then that largely defeats the benefits of installing a heat pump in the first place. 
As for Tasmania, options are as follows: 
Off-peak tariff 62 (at least 9 hours per day between 8pm and 7am, in most cases you'll get about 10 hours in practice) = 10.357c / kWh 
Off-peak tariff 61 (at least 9 hours at night plus at least 2 hours between 1pm - 4:30pm, in most cases the actual times are 10 hours at night and 2.5 hours in the afternoon) = 10.997c / kWh 
HydroHeat tariff 42 (24 hours supply for specific uses. Heat pump, solar and conventional electric storage (not instantaneous) water heaters are allowed under this tariff which also applies to various types of space heating) = 13.659c / kWh 
Tariff 31 (24 hours, no restrictions on what it is used for) = 22.646c / kWh 
In practice, in Tas you would normally use either HydroHeat (Tariff 42) or Off-peak T61 for a heat pump water heater. There's no valid reason to pay a fortune for tariff 31 unless your annual usage is so low that the additional supply charges for the other tariffs make them uneconomical.  
Which one would partly depend on whether you had either installed for some other use as well since both also attract a daily supply charge. If you've got space heating on one of those tariffs then for a heat pump water heater it would normally be cheapest to run that on the same tariff as the heating, either off-peak or HydroHeat, thus avoiding an additional supply charge for another tariff used only for the heat pump water heater. 
In terms of ambient temperatures and their effect on heat pump efficiency, I've done the maths for typical usage (hourly hot water usage data from Aurora Energy, the electricity supplier here) and it turns out that there would be no real difference in efficiency between tariff 61 (off-peak with afternoon boost) and a 24 hour supply tariff, so running costs would be lower on 61 due to the energy being charged at a lower rate. 
There is however a loss of efficiency if the night-only off-peak tariff 62 is used with these heat pump water heaters (this issue does not apply to solar or conventional electric water heaters, only to heat pumps). It would actually be cheaper to run a heat pump on tariff 61 than on 62 for this reason. The lower energy rate for 62 being more than offset by the reduced efficiency of the heat pump at lower temperatures.

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## woodbe

> Dunno if it's different down in Tassie, but tweo separate sparkies have told me it is "a requirement" to fit heat pump HWS to Peak rather than Off peak supply.

  It's not a requirement in SA either. Speak to your electricity provider, but this 'requirement' sounds like hogwash. Try a different sparkie.  :2thumbsup:  
We've a Siddons unit on offpeak, 4 person household. Never have a problem with hot water. Saves heaps over the old storage unit and using 2-3kWh per day average. 
woodbe.

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