This is my first post. I have learned a ton from the TFP website and I'm hoping to be a good contributor here in the future. I already have my TF-100 kit!
We are getting close to completion on our new pool. We'd like to use the pool for a couple of weeks before it gets too cold. Daytime highs are still in the high 80's here in Austin, TX.
We didn't specify a pool heater and I'm thinking about trying to get some heat into the water in the first fill. I don't have a pool heater but I do have a perfectly good regular 50-gallon tank-style domestic water heater rated at 36,000 BTU/hr (the same one that supplies the hot water to my house, of course!)
I am thinking of filling the pool from the hot water tap. Of course I understand that after the first 50 gallons, the water will be barely warm - that same temperature you get when someone else took a shower before you and didn't leave you any hot water. But that's still warmer than the water coming out of the cold water tap, and that's good, right?
I tried to do the math... if I have a 16,000 gallon pool, that's about 133,000 pounds of water.
If I can get 500 gallons/hr from the hot water tap, I'll fill it in about 32 hours, so that will be 32*36,000 = 1,152,000 BTUs of heat into the water. 1,152,000BTUs/133,000lbs = 8.6 degrees, or maybe a little more than that if the hot water doesn't run that fast.
So by my math, by filling from the hot water tap, I'd be able to increase the temperature of the pool for the first fill by a useful 8.6 degrees compared to filling from the cold water tap.
My poolbuilder said he never heard of anyone trying this. Does anyone have any opinion? Tried it? Warned not to?