Cooling the pool

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M

mookie1010

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May 21, 2015
7
Dallas, Tx
Hello everyone - I live in NTX and have very little shade for my 14000 gallon shallow kidney shaped pebbletec in-ground pool. With all the sun and heat, the pool is getting to the point now the water temp is getting right around 90*F during the worst of the heat of the day. Looking for ideas on how to lower it safely.

We have been using the fountain pictured below during the very early parts of the morning through the early afternoon to try to get some evaporative cooling. Doesn't seem to be doing much, but it's still nice to listen to and occasionally cool off under while in the pool.

I have been tinkering with the idea of a 304 SS heat exchanger attached to a return in a similar fashion to the fountain, that would sit in a pool of ice water, and then go back to a sprayer to sort of envelope the pool in a very cold spray of water, or even just feed it back into the pool to lower the temp as much as we can. Similar concept to a jockey box if you know what that is. I'm afraid this might cumbersome (ice in the cooler) and inefficient (lots of ice with little result.

Anyone tried anything like this?

Heat exchanger:
71ZiDoff7CL._SL1500_.jpg



Fountain

51k20IJaDbL._SL1153_.jpg
 
True, 100% of the coldness would transfer to the pool water rather than losing some to the air. But, I knew a guy who bought a bunch of 20ish lb ice blocks and put them in his pool and it didn't really lower the temp. I don't know how many ice blocks come in a bunch either. :)
 
The re circulation is theoretically where you would gain efficiency, though I wonder if the gains would be worthwhile. When you dump ice in the pool, you are lowering that area, which would eventually return to the mean temperature of the pool. By recirculating water you would be slowly continuing to lower the pool temperature. Stands to reason that the water temp would go down at a greater rate than with just the ice. But again, it might not be by much...

I dunno. I like experiments. Might give this a shot after the holidays.
 
unfortunately, the amount of ice you would need would be prohibitive to get the cooling you desire. It has been a long time since I calculated cooling tonnage but, if i recall correctly but, our machining coolant sump at work holds 3,000 gallons of water based coolant and we run something like a 20 ton chiller on it to pull the heat out and keep it somewhere near 75 deg.

An interesting tidbit of info, The cooling term TON came from the old days when they would use blocks of ice as refrigeration. A ton if ice was able to do a certain amount of cooling work




Dan

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mookie1010 said:
The re circulation is theoretically where you would gain efficiency, though I wonder if the gains would be worthwhile. When you dump ice in the pool, you are lowering that area, which would eventually return to the mean temperature of the pool. By recirculating water you would be slowly continuing to lower the pool temperature. Stands to reason that the water temp would go down at a greater rate than with just the ice. But again, it might not be by much...

I dunno. I like experiments. Might give this a shot after the holidays.
Click to expand...

to get a good transfer of energy in an exchanger, you will need to have it in a liquid (water) with the ice. Either way, the ice is going to melt at a rate equal to the heat load you are trying to pull out of the pool. Still worth the experiment.
 
I just bought that exact fountain and have been quite pleased with it. The cooling effect is noticeable, however it's difficult to know exactly how much you are getting. I run mine during the day for 10 hours, and have it cranked up to a 9' tall fountain.
 
I also live in TX and it is hotter than snot right now. My daytime pool temp was 93 degrees and it was too hot to even swim in.

I had forgotten about running your water features at night until I cam across it again here just the other day. Luckily we have two squirters or streamers or whaterver you call them and a large fountain, so I set my timer to run from midnight to 5 a.am. with pump on high with all 3 features going. I have cooled it down to 87 degrees most mornings! One day we had a little cloud cover and the next morning it was 85 in the middle of summer! I was impressed. I believe the key to really dropping it is a lot of aeration, and in the coolest part of the night 11-6 or 12-5 like I did it. It works!
 

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duraleigh said:
nlindelldc has it right. the evaporative process is the only practical way to cool a pool. Several of us have done it successfully and there is more than one thread in the forum.

A Cheap Pool Cooler for the end of Summer
Click to expand...

That is an epic DIY success! If I didn't have all of the water features I would definitely do that. So I read some conflicting things on that thread about running at night vs. during the day. I've been running at night with much success, but would running in the day help more or less or about the same? It's always humid here and hot during the day. Curious as to your thoughts. I guess I just assumed night time was best.
 
We might need a meteorologist but I think daytime is best. The temp/dew point spread is greatest in the afternoon so I believe you will evaporate more water.

At night, the temp/dew point is quite close (sometimes none in the wee AM) and that is not conducive for evaporation......that is a layman's opinion.
 
duraleigh said:
We might need a meteorologist but I think daytime is best. The temp/dew point spread is greatest in the afternoon so I believe you will evaporate more water.

At night, the temp/dew point is quite close (sometimes none in the wee AM) and that is not conducive for evaporation......that is a layman's opinion.
Click to expand...

Well that certainly makes sense if evaporation is what we're going for. More aeration, more evaporation. I guess the only way to know is to switch up my timer and run my 5 hour nighttime water features in the heat of the day (say, noon to 5 or 1 to 6). I think I'll try it out and report back AFTER July 4th weekend. I'm sure enjoying my cool water temps at the moment!
 
Good deal! We need some data. I tend to think running at night is better because you expose the water to lower temps. But, the evaporation theory is logical, spock.
 
I think we can solve this with empirical data. The fountain is acting like a refrigeration system, so really what you want to measure is the delta T (delta temperature across the return temperature and the temp of the water from the fountain as it lands right on the pool surface). It's difficult to measure accurately, but my kitchen thermometer shows around 2 - 4 degrees F. I thought it would be more than that. But if you can pull a larger delta T at night, you will have better cooling performance. But my money is on the evaporative cooling effect that you can get during the day with the lower humidity values.

Also daytime fountains have fringe benefits: you can swim underneath them and get the full cooling effect raining down on your head! Very refreshing. Also they look cool and makes soothing sounds.

Fountain.jpg
 
The other fringe benefit is that I was able to aim it at at dead spot in the pool where there aren't any returns. So where the water lands it spreads out with high velocity on the surface. It has really improved the circulation in the pool and I have less debris floating and sinking there. It does pull the pH higher a bit, which is a downside on a BBB system I guess. Lower alkalinity helps with that (mine is 70).

For $12 you just cannot go wrong here. :cool:
 
C3Cl3N3O3 said:
The other fringe benefit is that I was able to aim it at at dead spot in the pool where there aren't any returns. So where the water lands it spreads out with high velocity on the surface. It has really improved the circulation in the pool and I have less debris floating and sinking there. It does pull the pH higher a bit, which is a downside on a BBB system I guess. Lower alkalinity helps with that (mine is 70).

For $12 you just cannot go wrong here. :cool:
Click to expand...

my TA is 70 also and I have noticed just a slight drift. Have you ran it at night also vs. the day?
 
nlindelldc said:
my TA is 70 also and I have noticed just a slight drift. Have you ran it at night also vs. the day?
Click to expand...

No I sure haven't. It runs along with my pump for 10 hrs during the day (which I may drop to 8 this year once things settle out).

But if somebody else wants to run the experiments and post the results I'd love to see them. :p
 

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