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.
Reading an earlier thread:
"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?