Solar Pool Heating Questions

[w00dy]

We are in the Santa Cruz mountains with a new pool - the design included pre-plumbing for Solar heat and so far, with our very warm summer, I haven't thought about hooking up solar at all. We have had to dump heat at night by opening our safety cover on a few occasions, as our water temp started getting over 90°.

Now that summer is dwindling down, I wonder what peoples thoughts are on how much solar could extend a swim season in the Bay Area - we are just above the bad fog and get sun most days, some wind, but are sheltered from the prevailing coastal winds. Our pool is 14K gallon, 4500 sq/ft surface, max 5ft deep, with a dark finish. We also have all day sun exposure on pool and roof area where we would put the panels. Our automation is already setup for Solar as well.

Can we get an extra few months each side for swimming???

[J.P.M.]

Keep the cover on the surface when the pool is not in use, day and night. I had a motorized pool cover in Albuquerque. It needed replacing when I bought the house and got replaced with a dark brown cover, thus sort of doubling as a pool heater. The pool stayed above 80 deg. F. from about April to the end of Oct., with summer heat gain requiring nite heat dumping as you describe. The pool was covered except when in use or for heat dumping. I installed a CH4 fired heater that was never used. Albuquerque is sunnier than the Santa Cruz. mts., but a pool cover ought to extend your season by ~ 4-6 weeks on the season tails. See how it goes and if needed, start adding something like Fafco panels or get a CH4 fired heater if solar thermal is uneconomical or impractical.

[w00dy]

Keep the cover on the surface when the pool is not in use, day and night. I had a motorized pool cover in Albuquerque. It needed replacing when I bought the house and got replaced with a dark brown cover, thus sort of doubling as a pool heater. The pool stayed above 80 deg. F. from about April to the end of Oct., with summer heat gain requiring nite heat dumping as you describe. The pool was covered except when in use or for heat dumping. I installed a CH4 fired heater that was never used. Albuquerque is sunnier than the Santa Cruz. mts., but a pool cover ought to extend your season by ~ 4-6 weeks on the season tails. See how it goes and if needed, start adding something like Fafco panels or get a CH4 fired heater if solar thermal is uneconomical or impractical.

Thanks for the reply - yes I think we are going to see where this season and next years spring season puts us heat wise. I don't think we will do a gas heater at any point. We will just do Solar if/when it looks like it would give us a big advantage for extending our swim time.

I have even looked at using the solar for nocturnal cooling - and based on our small sample this summer if we ever get an extended heat wave with our pool we could certainly benefit from that it seems. Our automation doesn't support it but I am trying to figure out how to do it without manually switching valves.

I guess I wanted to see what any other Bay Area people have experienced. One or two pool and solar "sales people" talk about how great solar is, but then when you talk to installers and pool construction supervisors, who see everyday use, they mention that the actual usage people get from the solar panels is less than expected in our area. My neighbors have pools, one has no heater, one uses his heater only in the winter and real off season.

[Yaryman]

Just a note about a pool cover. As most of California is under water rationing, a pool cover will cut down on the amount of water lost to evaporation.

From my limited and frustrating research there was an article from a water district the claimed evaporation could be from 1% to 4% each day on a uncovered pool.
Taking just the low number on my 10,000 gallon pool, that 100 gallons a day, or 3000 gallons a month. That's a mighty big number when you are limited to just 11,000 gallons a month.
So not only will a cover keep the pool warmer, it will save you water.

[w00dy]

Just a note about a pool cover. As most of California is under water rationing, a pool cover will cut down on the amount of water lost to evaporation.

From my limited and frustrating research there was an article from a water district the claimed evaporation could be from 1% to 4% each day on a uncovered pool.
Taking just the low number on my 10,000 gallon pool, that 100 gallons a day, or 3000 gallons a month. That's a mighty big number when you are limited to just 11,000 gallons a month.
So not only will a cover keep the pool warmer, it will save you water.

Yes we have an automatic safety cover, and it seems to be helping a ton with water evaporation (thus even more heat is retained), lower filtration time, lower chemical needs - and it seems to keep the pool really warm. Just last night our low was in the upper 50's and we did lose a few degrees on the water temp - but much less than I expect would lose without the cover.

Since it is already almost October and the pool is staying in the low 80's temp wise. Granted this is our warmest time of year generally.

[J.P.M.]

The pool cover I had in Albuquerque just about killed evaporation losses, but then, the cover was in place about 15-20 hrs./day, more in spring/fall. Chemical use also dropped quite a bit.

[inetdog]

The pool cover I had in Albuquerque just about killed evaporation losses, but then, the cover was in place about 15-20 hrs./day, more in spring/fall. Chemical use also dropped quite a bit.

Did you notice a reduction in heat needed too, or just assume you were getting that advantage because of the measured reduced evaporation?

[J.P.M.]

Did you notice a reduction in heat needed too, or just assume you were getting that advantage because of the measured reduced evaporation?

Short answer : The pool needed no aux. heat. Water added amounted to ~ 50 gal./month or less in a very arid climate.

The pool cover was dark brown and covered the pool at all times when the pool was not occupied. The pump circulated H2O ~ 8 hrs./day ~ 0800 - 1600 hrs. The cover did double duty as a cover and solar pool heater. Water temps from ~ mid/late April to ~ mid Oct. ran 80+ to ~ 90 deg. F., hottest June - August. Some nite time uncover needed to keep temp. below 90 F. Rain water removed from cover as needed to reduce evap. loss.

The system worked well and was fit for purpose. The motorized cover sys. came w/ the house. I replaced an older cover w/the darker one to see if it would heat the pool in lieu of a std. (Fafco, etc.) pool heater. Pool chem. use also dropped drastically and cleaning was a much easier chore.

[w00dy]

I thought I would update my thread based on our spring pool experiences this year.

The pool with a dark green automatic safety cover in place most of the day doesn't look like it will need additional solar heating. During March our temps crept up from the winter 50°'s to around 68°, by early April it hit the mid 70's after just one hot day. Over Spring break it was just warm enough to comfortably swim. By May the water temperature reached 78-80° without any long stretches of hot sun and lots of clouds and even rain almost every week between mid April and mid May. Now water temperatures are in the upper 80's - prefect for swimming!

I can't imagine that having the water warmer, in say March, would have mattered - it was never warm enough in March for me to want to jump in the pool - I don't want to swim in cold weather!

We are sticking with what we have and will save $4000. In the future we can always add solar.

[J.P.M.]

I thought I would update my thread based on our spring pool experiences this year.

The pool with a dark green automatic safety cover in place most of the day doesn't look like it will need additional solar heating. During March our temps crept up from the winter 50°'s to around 68°, by early April it hit the mid 70's after just one hot day. Over Spring break it was just warm enough to comfortably swim. By May the water temperature reached 78-80° without any long stretches of hot sun and lots of clouds and even rain almost every week between mid April and mid May. Now water temperatures are in the upper 80's - prefect for swimming!

I can't imagine that having the water warmer, in say March, would have mattered - it was never warm enough in March for me to want to jump in the pool - I don't want to swim in cold weather!

We are sticking with what we have and will save $4000. In the future we can always add solar.

Your experience is very similar to mine. I had a motorized cover in Albuquerque. Dark brown, covering the pool except when the pool was being used, except in high summer and then mostly uncovered, +/- some.. No aux. heat needed. Pool was useful from approx. April through early Nov. Cut way down on chemicals and cleaning as well.