# Thread: New pool, first fill - from hot water tap?

1. ## New pool, first fill - from hot water tap?

Hi,

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?

Many thanks,

Marc

2. ## Re: New pool, first fill - from hot water tap?

It won't hurt anything but your gas bill.

Be sure to get a solar type cover, though. Most heat loss is at night, since the warmer water rises to the surface where the cold night air is.

Give it a shot, and let us know how it goes.

3. ## Re: New pool, first fill - from hot water tap?

Have at it but it won't work.

Radiant and evaporative heat loss will probably cancel ALL of the heat gain. Additionally, you will have no hot water for your house

4. ## Re: New pool, first fill - from hot water tap?

+1 to the solar cover, from what I have been reading here the cheap ones last pretty much as long as the expensive ones.

5. ## Re: New pool, first fill - from hot water tap?

Thank you all! Solar cover it is... starting to fill on Sunday if all goes well...

6. ## Re: New pool, first fill - from hot water tap?

Here's a question, "What is the temp of your cold water?" Your 8.6 rise will be from that. Also, your heater will be running the whole time you are filling. Are they even designed for that?

7. ## Re: New pool, first fill - from hot water tap?

Welcome to the forum Marcgr

Besides heat I think the solar cover is also helpful in keeping your chemicals a bit more stable and also keeping some leaves and dirt out.

8. ## Re: New pool, first fill - from hot water tap?

So, we filled it up yesterday, air temp in the 80's, water temp 76 straight out of the cold water tap, and we swam!

Solar cover arrives Wednesday, hopefully we'll get a couple of weeks of swimming before it gets too cold...

Thanks again all!

9. ## Re: New pool, first fill - from hot water tap?

Wow! My cold water is like 50 degrees! No wonder you were thinking of using the water heater.

10. ## Re: New pool, first fill - from hot water tap?

So, now I am discovering that my new solar cover is not compatible with my PV3 infloor The infloor directs water on top of the cover when it runs. I will have to figure out a fix for that...

Nevertheless, my water is still 76 degrees, have been swimming in it every day!

11. ## Re: New pool, first fill - from hot water tap?

Place the solar cover on during the evening and leave it on until the morning. Then after you remove the cover run the filter, etc. I plan on purchasing a cover next year and this is the only thing I can think of. If this PV3 is infloor, where does the water come from? What exactly is it?

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