Any Arizonans using their solar heaters to cool the water?

[twd000]

When I moved in there were a dozen leaky black coils on the carport roof for an old solar heating system. I was told it would cost $6000 to replace them, but couldn't justify the cost since the pool is open 6 months a year with just a bubble cover.

After two summers, I am trying to figure out the trade off between chlorine consumption and evaporation. When I leave the cover on during the day, the water can reach 95, about 10 degrees too hot for me. I know that chlorine consumption is exacerbated buy high temperature as well as direct sun. So I'm interested in leaving the cover on, while dropping the temperature to 85 or so.

Most cooling solutions are really just evaporation driven, and it gets expensive refilling the pool every week.

So if I were to replace the solar coils, could I run my pump from 2-6 am and expect 10 degrees of cooling,? Is anyone in Arizona successfully using a bubble cover and solar coils in conjunction?

 

[Casey]

I can't answer how fast you could drop your temps but running at night through the solar can help drop the temps!

Good Luck and we'll wait and see what other's in your area are doing.

 

[twd000]

I saw these panels for sale on Craigslist

http://tucson.craigslist.org/for/4519467380.html

Do you think there would work for my application?

How many panels would I need for a 25,000 gallon pool? They would be installed on a flat carport roof with full sun in the daytime. I'm not sure how quickly it the roof cools at night

Is this a reasonable DIY job? Are there controllers out there that can be set for differential temperature, heating in the off-season, and cooling in the summer?

 

[jblizzle]

I am pretty sure those panels are not supposed to be run vertically like shown on the house in the picture ... hope that did not damage them.

I got 11 4x12.5' Heliocol panels off the Phoenix CL for a similar price. There are always panels available in PHX. But it is a risk as you do not know if they leak.

I have 500 sqft on my 18k pool. That would give you 400 sqft on your 25k pool. It will certainly help some.
Honestly I have never needed to cool my pool, so never run at night, but it should work.

I think the Pentair Suntouch allows a cooling mode and may even be able to turn on the pump. My Hayward Prologic only has heating mode, so I would have to manually switch the solar on at night.

 

[duraleigh]

Most cooling solutions are really just evaporation driven, and it gets expensive refilling the pool every week

Check your math, perhaps.

I find the evaporative loss when I cool my pool with a spray fountain to be pretty minimal.....somewhat surprising as I assumed it would be more.

Even if you had a lot of evaporative loss (say, maybe an inch a day) I think you would find that replacement cost to be under $5.....I don't know your water rate.

 

[jblizzle]

1" could be around 250 gallon / day. The water here does not go much above $8/1000 gallons. So that may be $2/day = $60/month which is not insignificant. But, I am not sure you are actually seeing 1" per day.

How hot does your pool get? Do you use a cover? I have not found that either of my pools get too hot unless I run the solar heater too long (before I got a controller). I do not use a cover.

 

[tucsontico]

My pool is close to 20k gallons and is in full sun all day. I have, and use, a 12 mil clear solar cover (bubble wrap style). During the triple-digit days here in Tucson my pool temp will rise easily to >95º within two days with the solar cover on. Those high water temps coupled with the FC level in your pool will deteriorate any bubble wrap cover pretty fast. In fact, the owner's manual for my cover states that water temps above 90º will shorten the cover's lifespan and it isn't warrantied for those high temps. So during the summer heat, I only put my cover on at night to hold the water temp. Leaving the cover off during the day holds my water temp at an average 84º from late Apr-Sep.

I haven't accurately measured my actual evap rate/day, but the difference in my water bill from May 2012 (before pool install) to May 2013 (after install) was only $25–or about 85¢/day. (I do have an auto-filler for my pool.) The cost for my May 2014 bill is within $2 of my May 2013 bill so I think it is a reasonable estimate of my increased water use with the pool.

Running a pump for 4 hours/night to cool the water while attempting to keep the evap down with a bubble cover may not be cost effective if you take into account the cost of replacing the cover more often.

 

[Isaac-1]

That appears to be a fair price on those used panels, assuming they don't leak, etc. Be aware they were only mid quality panels to begin with

 

[twd000]

1" could be around 250 gallon / day. The water here does not go much above $8/1000 gallons. So that may be $2/day = $60/month which is not insignificant. But, I am not sure you are actually seeing 1" per day.

How hot does your pool get? Do you use a cover? I have not found that either of my pools get too hot unless I run the solar heater too long (before I got a controller). I do not use a cover.

Pool gets to 95 with a cover, I would like to maintain 85. Probably losing 1/2" per day without cover in a 12'x25' pool.

Has anyone done a controlled experiment comparing increased chlorine consumption due to 10*F increase under cover, compared to full day sun without cover? I have heard chlorine degradation is affected by both

What is a good brand of solar panels to look for?