1. ## Solar vs Heat Siphon. Cost considerations, need advice

For my 5400 gallon IG in NC, dig starting tomorrow!, I'm considering adding a heater. Initially I thought about solar but now I'm reconsidering a Heat Siphon.

"Ok, some assumptions we can use. If you want tto fire it up on friday and run it thru the weekend, lets figure it's early May, your pool temp is 72 degrees and you want to rasie the temp to 86 degrees. Thats a 14 degree rise. You have a 25,000 gallon pool. To figure all this out, you need to know that 1 BTU will raise 1 pound of water 1 degree. So, for 25,000 gallons of water, that 208,250 pounds of water (8.33 pounds of water per gallon). Doing the math, thats 2,915,500 BTUs that need to go in the pool. For a 400,000 BTU heater, that means it will have to run ~7 hours to bump the temp 14 degrees. For an LP cost of \$2.50, that \$70 to jack the temp on a friday. Do this 4 weekends in a month, that \$280 a month. This does not take into account what the drop is overnight thru the weekend."

I calculated a cost of under \$10 to take my pool from 70 to 86 degrees with a Heat Siphon. Initial cost is much higher than solar but also much easier to install. The 54,000 BTU unit would allow me to keep the pool comfortable for an extra couple of months per year.

My biggest question is how to estimate average monthly cost for the heat pump. If lets say \$8 raises temp 16 degrees would it cost \$1-2 per day to maintain the temperature? I just don't want to make the same mistake that I did with my last pool. It was over 50,000 gallons and I added an LP heater. It would suck down over \$500 in gas in a week and that was over a decade ago. With a small pool is the Heat Siphon reasonable for monthly use?

2. ## Re: Solar vs Heat Siphon. Cost considerations, need advice

I have a heat siphon heat pump.. my pool is about 26000 and it keeps it heated just fine... the only thing about a heat pump is that it takes awhile for it to heat up... and it only works above 40deg outside temps... but we start to heat it in April and we swim until late Oct...and we keep it pretty warm... 88 to 90. with out figuring out for sure what it cost per month.. but i would say around 125.00 per month... and we do keep the solar cover on when we are not swimming... it may take a week to heat it up in the spring but once you get it there it will maintain the temp you want...
good luck

3. ## Re: Solar vs Heat Siphon. Cost considerations, need advice

when you heat the water at the begining of the season do you leave the heatpump running 24/7??? How long does it take to heat the water up??

4. ## Re: Solar vs Heat Siphon. Cost considerations, need advice

I just ordered mine today. I asked the same question and was told with my pool that it would take 24-48 hours to get to 84 degrees.
Their pool analysis does not provide that piece of data. It does tell you amount of time per month and costs per month/year. Pretty nice analysis for free.

I ordered from manufacturer since I don't have a dealer in my area. I did contact a net dealer mentioned on this forum but I got the buy it now price routine. I refuse to play that high pressure game and went elsewhere.

5. ## Re: Solar vs Heat Siphon. Cost considerations, need advice

I am wondering if a heat pump would be an economical choice to use in conjunction with a solar system. It doesn't cost anything extra for the solar if it is already available/installed and using that inline AFTER the heat pump for temp maintenance? I still do not want to spend \$125 a month to maintain, especially with the initial cost of the heat pump being so huge.

6. ## Re: Solar vs Heat Siphon. Cost considerations, need advice

Originally Posted by NWMNMom
I am wondering if a heat pump would be an economical choice to use in conjunction with a solar system. It doesn't cost anything extra for the solar if it is already available/installed and using that inline AFTER the heat pump for temp maintenance? I still do not want to spend \$125 a month to maintain, especially with the initial cost of the heat pump being so huge.
I think that could work well. I've got the solar, no heatpump. I beleive there is a mode in my suntouch controller that let's it select solar if there is sun of heatpump if the roof sensor is not hot enough. You also need to remember the temp loss overnight and on cloudy days. This past month has been challenging fo solar here. The weather hasn't had more than 3 and usually 2 sunny days in a row with lot's of rainy days and nights in the mid 40's to low 50's. To give an example of the solar only performance on Friday the pool reached 79F, cover on overnight resulted in a 76F start temp on Saturday which was sunny and about 70 degrees. Saturday's peak pool temp was 81, dropped to 76 overnight then Sunday was overcast until about 2:30 then partial sun which got it back up to 81 by sun down. A supplemental heat system would have allowed us to crank it up a few degrees more for not much cost and used the pool rather than no use. Another 2 or 3 weeks and the pool will be 85 - 90 with just the solar.

7. ## Re: Solar vs Heat Siphon. Cost considerations, need advice

it took a week to get it to 90, but it shut its self off at night when the outside temp dropped down to 40 and it will not come back on unitl the outside temp is 50. So some days it did not come back on unitl 11 in the morning... hope this helps you..

8. ## Re: Solar vs Heat Siphon. Cost considerations, need advice

Thanks Hayfarmer!

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