# Forum Home Renovation Pools, Spa & Water Features  Which uses more electricity - Heat Pump or Solar???

## Typey

Hi 
I could see some posts from many years ago,
Wondering if technology has changes much.... 
I'm looking at heating a 30,000L pool, in Melbourne, and am wondering what would cost more to run electricity wise. 
1. A heat Pump 
2. A solar system on the 2nd story roof of my house 
And for that matter the average $$$ costs for supply and install of each system..... 
Also - does anyone know what calculations I can use to determine what equipment I would need to be looking for to do the job, KW's etc for pumps / heating etc 
Much Thanks

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## Uncle Bob

A heat pump will cost more to run.

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## SilentButDeadly

> A heat pump will cost more to run.

  Yep...because you need to run both the heat pump and the water pump.  Solar only needs the water pump

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## Smurf

A heat pump will use more electricity as such, but then it also provides a "guaranteed" means of heating the pool. 
If the solar also involved some means of boosting, particularly an electric element, then you'd need the solar to be providing 70% or so of the total heat input just to break even with a heat pump. Depending on climate, design of the pool, roof area etc that may or may not be practical.  
Of course, if the solar requires no booster or if the booster is a heat pump then solar is a very clear winner. 
Further complicating it is cost as distinct from energy consumption. Eg heat pump running on daytime power rates? Or running at half price on off-peak electricity? Same issue with any boosting if electric, or the difference in cost between gas boost versus electric boost. 
Personally, I'd go solar especially if you won't be using the pool in the middle of winter anyway as I'm guessing maybe the case.

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## Oldsaltoz

Some brands of the heat pumps have proven to be of poor quality. Talking to a builder last year he had to replace 4 of 10 units installed on new homes. 
Sorry I do not recall the brand.

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## Bloss

Roof top solar - black plastic pool heating no question. And in most places in Australian there is more than enough heat falling on the roof to maintain the water temperature all year round - even in Canberra. So long as you use a decent pool cover. Of course whether you want to swim in the open when air temperatures drop below 18 or so is the question. In Scandinavian countries and Iceland it is common to swim in water at 28-32 degrees while the air temperature is at or close to zero, but few in Australia would venture to do that I reckon. 
The water is circulated by the pool pump in most e.g.:http://www.waterco.com.au/component/...r-pool-heating or http://www.directpoolsupplies.com.au...ating-diy-kits - & plenty of others

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## r3nov8or

> .... And in most places in Australian there is more than enough heat falling on the roof to maintain the water temperature all year round - even in Canberra. ...

  Really? The table at your second link disagrees. I also think that table exagerates - the site is more interested in selling product than the truth.

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## r3nov8or

Back to the original question, a heat pump will cost more to run. But  the right one will also heat your pool water down to an ambient air temp of 14C and  bigger units will extend your swimming season for about 3 months longer  than solar. It's really a question of what lifestyle you want.

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## Bigboboz

Couldn't you in theory run the heat pump on off peak power?  Of course it would reduce the window in the year that it will be effective but it you're just wanting to extend a bit but mainly boost the temp in general?  How does it then compare?  Doesn't seem like a straight forward calc...

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## r3nov8or

> Couldn't you in theory run the heat pump on off peak power?  Of course it would reduce the window in the year that it will be effective but it you're just wanting to extend a bit but mainly boost the temp in general?  How does it then compare?  Doesn't seem like a straight forward calc...

   Yes, this is feasible, but it will be a balance of how long it needs to run during the versus night. On a day when the direct sun does a lot of the work, and the temp is much warmer so the HP can suck more heat more quickly, a HP may only need to run a couple of hours to top up the heat. Overnight, where ambient temps are obviously lower it would need to run much longer for the same heat gain, so the power use may end up similar anyway.  
Also the units aren't noisy during daytime ambient noise, but it's a different matter in the dead of night, and council noise restrictions and neighbour happiness come into play. 
As I mentioned above, it depends on lifestyle a lot. A HP will heat a pool on a very cloudy but warm day and keep going when the sun goes down on a warm night (e.g. party needs), where solar won't. Some people choose to top up their solar heating with gas fueled  heating for special occasion use to guarantee a heated pool.

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## Bloss

Best option if you really must is heat pump and solar PV system, but not cheap.

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## Bloss

> Really? The table at your second link disagrees. I also think that table exagerates - the site is more interested in selling product than the truth.

  Real life in ACT is that the passive black plastic systems work well. BUT - the pool must to be covered at all times when not in use and the rise in winter might not be sufficient for those wanting a warm swim. But I know many who have pools that can be kept at 20-22 in winter - not hot enough for me, but quite a few brave souls reckon that's OK! Of course with overnight temps in the minuses and daytime maximums in the low teens one has to be at least a little mad to use an outdoor pool in Canberra even if it feels warm while in it!   :Eek:   :Biggrin:

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## Marc

Heat pump suck. Solar all the way. You could even have a pump run by solar. Not cheap but duable and zero electricity usage.

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## r3nov8or

> Heat pump suck. ...

   Care to elaborate Marc?

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## Bloss

> Heat pump suck.

  Actually they suck and blow . . . and are very efficient use of energy with even the worst providing 3 times as much heating and cooling than the input energy. The best provide nearly 6x times as much heating & cooling as the input energy needed to drive them. And there are many in between that 3x & 6x with new units coming out at higher performance still. That's why they are called 'pumps'. 
For heating pool water they are an expensive option compared with the simple black plastic roof top 'spaghetti' solar pool heating, which usually uses the pool own pump to circulate. 
This QLD site has some numbers, but they would not apply in Victoria Pool Heat Pump - Pool HeatingThe Pool Heating Specialists

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## dawesius

Be sure to have your heating requirements assessed by a manufacturer; even better, get a few quotes and compare the calculations they come up with. There is a huge number of factors in play when determining how much heating your pool requires.  
A heat pump on a smallish pool, with a cover, out of the wind, *may* certainly provide sufficient heat simply during the filtration cycle (ie offpeak) to be a season extender, meaning the pool will be warm enough for a swim, whilstever its still warm enough outside to want to go for a swim. If you are after year-round swimming, I'd suggest enclosing in an insulated room, and (seperate) heat pump heating both pool and room, it will reduce total heating (and hence power) substantially. 
Solar provides the heat for free, but you still have to pump it up there, usually a 750W pump, perhaps even 1100W for the 2nd story, and during the day (usually shoulder/peak) 
Again, best bet is probably to have a few systems sized and quoted for you.  
And get the cover first, a good solar cover is usually more than enough heating on its own up here further north, solar/heat pump systems only used to push water temps up in shoulder season, and you wont lose all your heat overnight and through evap.

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