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Thread: In-ground pool solar heating question

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    AV8TOR's Avatar
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    In-ground pool solar heating question

    I have started looking into the addition of solar heating to our 14,000 gallon in-ground pool. I am leaning on a simple manual system with panels like a Favco. I am sure from the reading I have done and some experimenting this season that I will be happy with it. My concern with a system like the Favco that mounts on the roof of your house is holding up to the intense summer sun and temps here in Texas.

    Is anyone running solar panels up on your roof in Texas or in an equally hot climate? Do you just put them in by-pass and just let them sit there all summer? This summer I needed to go up on the roof and I could not believe hot hot the roof shingles were and they were not black. I am concerned about this and I have been thinking that maybe a system like for above ground pools might be better where you can take the panels down during the hot of summer and only put them up late winter and late summer.
    16,000 gal IG Double Roman Plaster Pool (16yrs - plaster redone 2014)
    Pentair FNS-48 DE filter with WhisperFlo 2HP single speed pump
    Polaris 280 robot
    BBB all the way and tested with a TF100 kit
    Pool Calc user

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    mas985's Avatar
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    Re: In-ground pool solar heating question

    I don't live in Texas and I don't even have the Fafco panels but I think most of the panels are built to survive in the hotest climates so that shouldn't be a problem. The biggest risk is to the PVC pipe that is usually installed with the panels. If water sits in the pipe during the heat of the day and the pump shuts off, the vacuum due to water draining can cause the pipe to collapse. Some installers have been placing the release just above the pad for easy access and have noticed that under some conditions, the return pipe on top of the house can collapse. But again, this is only for very hot climates. This is one of the reasons I always recommend that the vacuum release valve is installed at the highest point and near the return pipe for very hot climate installations. Not very convienent for replacing but can prevent some more expensive repairs. CPVC is also another option for the solar plumbing but is fairly expensive.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner

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    AV8TOR's Avatar
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    Re: In-ground pool solar heating question

    Many of the systems I have seen have the check valves just as you mention but I have not seen one up close. Are they basically a 1 way check valve? Can they be purchased separately?
    16,000 gal IG Double Roman Plaster Pool (16yrs - plaster redone 2014)
    Pentair FNS-48 DE filter with WhisperFlo 2HP single speed pump
    Polaris 280 robot
    BBB all the way and tested with a TF100 kit
    Pool Calc user

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    mas985's Avatar
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    Re: In-ground pool solar heating question

    First some clarification:

    Check valves usually go near the pad on the return side of the solar pipe. This prevents water from flowing backwards up the return pipe when the solar valve is off.

    A vacuum release or breaker valve allows air to enter the solar lines when the pump is shut off. This allows the water to drain out of the solar automatically so there is no water trapped in the solar panels and pipes. This is important for two reasons, the first as I explained in the post above. The second reason is in the winter, you don't want any water trapped in the panels that could freeze and damage the panels or pipes.

    Check valves and vacuum release valves are different valves but accomplish the same thing, one way flow. Some people have used check valves as vacuum release but I wouldn't given the design and chance that something might get stuck in the flapper if one end is left open to the air. That would cause a nice fountain on your roof. Vacuum release valves are specially designed to allow air to enter the panels and to close shut when water enters the pipe.

    Here is a check valve.
    Here is a vacuum breaker valve.
    Here is another type of breaker.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner

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    AV8TOR's Avatar
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    Re: In-ground pool solar heating question

    Thanks for the info Mark.

    What are the panels that you use in your signature, EPDM Solar Panel?
    16,000 gal IG Double Roman Plaster Pool (16yrs - plaster redone 2014)
    Pentair FNS-48 DE filter with WhisperFlo 2HP single speed pump
    Polaris 280 robot
    BBB all the way and tested with a TF100 kit
    Pool Calc user

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    mas985's Avatar
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    Re: In-ground pool solar heating question

    EPDM is a soft rubber type material. Most manufatures will have an EPDM product line but not all. Because they are flexible, they conform to the roof and can be routed around obstacles. They look like this:

    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner

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    AV8TOR's Avatar
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    Re: In-ground pool solar heating question

    Interesting thanks Mark. Is that your set up on your 20k gallon pool? Just for curiosity what is the diameter of the flow tubes? From the picture they appear to be 1/4" maybe. That is smaller than I thought? What is the length of that system?
    16,000 gal IG Double Roman Plaster Pool (16yrs - plaster redone 2014)
    Pentair FNS-48 DE filter with WhisperFlo 2HP single speed pump
    Polaris 280 robot
    BBB all the way and tested with a TF100 kit
    Pool Calc user

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    mas985's Avatar
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    Re: In-ground pool solar heating question

    No, that isn't my setup although it looks similar. I'm not sure of the length of the pictured system but mine is about 40' long. The ID of the tubes is about 3/16".
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner

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