# Forum Home Renovation Pools, Spa & Water Features  POOL HEATING:  Solar vs Heat Pump + PVC water pipe insulation

## drvik

Hi everyone, 
This is my first post here, on recommendation of someone from another forum who tells me all the smart people are here  :Biggrin:  
I apologise in advance for the long post, but I thought I would put it all into context.... 
We are planning to install a pool heating system. We are based in Brisbane, have a 8mx4m pool, and the pool receives a reasonable amount of sun during the day, missing out only during the early and late afternoon due to some shading.... 
Last year we went through the rigmarole of having companies come out and quote on solar pool heating, and in the end were unable to make a decision because of the wide variation of products and opinions... everyone had their own idea of what percentage of pool surface area to put up on the roof, with opinions ranging from 110% right down to 50%!!!!!!! Most companies offered some version of the rubber or PVC black strips, each proclaiming their particular design was the best, and getting specific, without providing any data... manifolds ranged from dodgy home built nipples screwed into PVC pipe to single piece injection moulded components... Additionally, every salesman will tell you what temperature YOU WILL want from your pool, and they all tell me that 27-28 degrees is standard swimming temperature... so then they base their "swimming seasons" based on the systems calculated ability to provide 28 degrees....  
Since that time, we were introduced to a a new line of heat pumps introduced into the market by Zodiac as a solar replacement... they are small little units, priced around the same as a solar system... they are designed to extend the swimming season by around the same amount.... and I have been told that they are a fairly efficient way of using electricity to heat the pool (COP around 4.5) 
Now as time went on and we used our pool more, we discovered that 28 is just too cold for us... once the pool is in the shade mid afternoon, we have found ourselves getting too cold after about 30 mins in a 29 degree pool... we tend to not use the pool (whilst paying filtration and chemical costs) for this reason and I would imagine, 30 is our minimum and we would like a system that has the capacity for 32 degrees.... 
Additionally, the wife doesn't like the idea of a pool cover, because the pool is the major feature in our "back yard" (designer home, tiny block of land)... though I think its inevitable, that I will incorporate a pool cover into the equation and I will most likely circumvent the "unsightly roller" issues by having the cover made up into 4 or 5 sections, allowing them to be lifted out and rolled up out of the way by hand. 
So inevitably, the thought of a heat pump has developed further, with an increase in size... calculations reveal that a 11-13kW pump running most of the day with a blanket on will be running at near maximum capacity, whereas a 17-20kW pump can cope with no pool blanket and will require less time during the day, which is relevant because we plan to use an off peak tariff (33) where we elect to use the pump between around 9am-4pm each day... for the neighbours sake, and for efficiencies sake, we do not plan to run the pump overnight.... 
So the main advantage of a heat pump as I understand it is the predictable heating, even on cold or rainy days. The other big advantage, is if we invest in a good unit now, we can just unplumb it and take it with us!! You can't really take your solar system with you!! 
The units we have been contemplating (we need upward exhausting fans) are the Rheem Accent (Sydney built) and the QIS (Brisbane built)... from what I understand QIS is a smaller local company and they construct their heat pumps locally from imported chinese parts.... The Rheem are australian parts with a German sourced Hitachi compressor... cost is around the same somewhere around $8k give or take with installation.... it's only since I started googling, that I have found that some people are having issues with the Rheem Hot Water Service, which is making me a tad nervous about my decision... but I'm not sure, given that Accent was a separate company until recently, whether this has any meaning... 
The company offering to install the Rheem unit have pointed out that we could use their solar system, with their higher density 14 pipe design, and said we can't go wrong with 150% coverage... he said any more than that and its a diminishing return (they use 400% to heat their spas to 36C)... He offered me this solution for $4500 and he prefers it, being a bit on the environmentally conscious side... 
I'm now quite undecided, and I am under some time pressure because there is some building work being performed next week and provides an opportunity to install the various pipes between the pool and the house... however, as either systems will use this pluming, we are having it installed anyway.... 
So this all leads me to my actual questions.... 
The run from the pool filtration area to where the heat pump will be sitting, or the solar wall pipes will start is around 15m... I have been told that they intend to use 40mm class 9 pipes. I asked about upsizing to 50mm to facilitate flow and they said "not required"... the heat pump would need 2.8L/s flow rate and they are installing a 500W pump to do so.... 
I also expressed concern about heat loss through the pipes and whether an upgraded pipe is an option.... again I was told that this was not necessary because the water wouldn't lose more than 1 degree during transit... I was also told that heat loss underground is less than heat loss above ground... I'm guessing this means because there is no convection loss?? 
From what I have been able to deduce myself using some resources on the net is that I will lose around 0.4kW/hr due do conduction loses (or 350 with 40mm pipe!)... does this calculation sound right?? I have made the presumption that the exit temperature of the heat pump is 32 degrees (the intended thermostat setting) but I'm not so sure now, that it won't be much higher than that in order to bring the temperature of the pool up... this would increase the heat loss due to the larger delta.... Is this significant enough to worry about? Should I attempt to reduce this further by buying more expensive class 12 pipes or investing in some form of insulation?? Also, these calculations are not taking into consideration the pipes running up the wall if solar is used. 
Am I silly for even considering a heat pump when I'm in Brisbane?? I do love the idea of "free" heat energy, but I'd hate to pay $4.5k, and find that the pool is not warm enough for our needs... the days are lovely and sunny now, but the evenings are a tad crisp, so an after dinner swim would benefit from a nice balmy pool... I was wondering whether we could start with a 150% coverage, and if that was insufficient during the fringe swimming months we could add more matting later... the other alternative, is we could add a small heat pump later as a "booster", but this then becomes a hybrid system that may raise a few eyebrows and I'm not sure how it would be plumbed in, and whilst the costs would likely add up to the same as a large heat pump, the overall running cost across a 12 month period would be reduced!!! 
So as you can see, we are a tad confused about the best approach.... either way, I would appreciate advice on the PVC plumbing/insulation issue, so that no matter what we choose in the end, we are making the most of the energy being harnessed.  
Thanks for your patience and looking forward to your opinions! 
drvik

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## Uncle Bob

Personally I'm waiting till the LENR (Low Energy Nuclear Reaction) systems become available  :Smilie:

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## Bloss

LENR systems are available - they are called solar heaters . . .  :Wink:  
Not sure who's been telling OP what, but in Canberra where even summer nights can drop to 12-15 regular simply black strap solar pool heating can take pools to well beyond 30 and keep them there for around 8 mths of the year. In Brisbane that's be a cinch to do so all year (unless you have no suitable roof space facing between NE and NW). Don't waste your money on any system that will continue to cost you money ie: any that uses gas or electricity regardless of the source (BTW - a COP of 4.5 is atrocious - easy to get 6-7 and over 10 is available overseas). All  energy prices will be increasing in coming years - your choice should reflect that (unless you are very certain of your capacity to pay). You need to invest in a pool cover regardless - and actually use it.

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## ob003

I'm in Sydney and installed solar last season.  
I put about 80% pool surface area on the roof. Now I have a very deep pool with very large volume compared with surface area. 36sqm with about 65~70,000L capacity, I find that this is not enough to consistently maintain 28deg or better.  I'm now looking at putting more PVC matting on the roof as I only run the pump during shoulder period, maximum of about 4hrs a day during weekdays. 
I have no experience in heat pumps, but I do work in the Energy industry, I would at all costs avoid expensive pumps as the price of electricity is only going up. 
I would suspect that with over 100% coverage plus good sun radiation directly into the pool you will get satisfactory results.  
Also, don't discount a pool cover, I'm now looking to install one of these as well to assist with heat loss over night and water evaluation. You can get some great looking units that disappear into decking.

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## Comfortablynumb

When you have a pool heating system of any kind, a pool cover is essential. 
Temperature losses overnight are quite considerable, more than you will believe possible. Temperature drops of 5 deg are entirely possible, even in summer. If the pool cover is on, then that is 5 deg the heating system doesn't have to make, just to get to where you were yesterday. If you are paying money to heat (electricity costs) the all the more reason. 
Also, the "cut evapouration" thing is a bit of a misnomer, in Brissy at least. I have to pump water _out_ of the pool all summer due to the high rainfall (twice today in fact, 35mm of rain.Good chance to backwash though). This means increased costs in salt and stabiliser just for starters. At times to pool is TOO warm....just with the solar cover !!! Gotta leave the cover of to let it cool a bit and suck some water out without costing me chemicals. Actually, the most evapouration occurs in winter (strange huh), at night (even crazier) because of the large difference in temp between the pool water and the air. Overnight temps in Brissy often get close to zero in winter. The pool water is nowhere near that, much warmer. Look at a lake next time on a winters morning and observe the mist rising....water vapour. THIS is when I use a cover the most. 
As for the "ugly" factor....yeah, you are right. Ways around it though. If you have a deck around the pool a "trench" with a lid could be installed at the end of the pool to slot the roller in when the cover is removed so it drops down under the deck. If not it could be rolled into a long wooden box that doubles as a seat. Plenty of options if you think a bit. 
BTW....a solar system is not "free" heat. It needs a pump (to circulate water at the correct rate) and this uses electricity. Using the pool pump is often not a good idea. It doesn't have enough spare capacity to lift the water onto the roof, around and down. Too much work for the poor thing and it will give up the ghost, not to mention reduced circulation in the pool, increased 'water change over time" and then clarity and chemical balance issues. It IS possible to have a solar powered solar circulation pump (phew). This costs more money of course.

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## Stace2025

Just wondering what decision you made with your pool heating - we are current in the same boat trying to decide on what heating we should do for our pool and also located in Brisbane so would be very interested to hear how you went and if you are happy with results?

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