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solar home made pool heater

formerfrankiewrenchformerfrankiewrench Member Posts: 1
It's been a very long time since I was active on this site. I am now retired in Palm Beach, and lovin' this life. My question is: I want to use 100'-200' of 3/4" black plastic coils as a heat exchanger. My plan is to tap into the filtered water 1 1/2" PVC using a Y connection, thru the coils and back into another Y, and into the pool. I'll be installing a throttling valve between the Y's and temp gauges, air eliminators, and purge valve set ups. My pool is about 10,000 gallons, currently pumping at about 28 GPM, 25 PSI static pressure at the single 1" orifice. I'm trying to figure out the pressure loss thru the HX tube, and what flow rate would be best for this application. There is also a control valve on the inlet of the pump if I need to slow down the flow, but I think I can use the HX valves for flow control purposes. Any takers???


  • Paul48Paul48 Member Posts: 4,492
    I think I'd use a circ, and pipe it P/S. Loading the pool pump will drive your electric bill up and probably kill it, in short order.
  • hot_rodhot_rod Member Posts: 13,475
    Unless you add flowmeters how will you know how much is being bypassed? You could just throttle the valve with an amprobe on then pool pump to get an idea where the pump is comfortable. You can usually hear the pump start to labor when you start shoving flow thru the pex loop.

    200' of 3/4 pex, probably get 4-5 gpm thru the loop, assuming the pool pump has enough capacity, the rest to the pool loop.

    That's not a lot of collector surface area, but then again how much heat do you need to add to a pool in Florida?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Larry WeingartenLarry Weingarten Member Posts: 1,819
    Hello: An old rule of thumb for sizing solar pool systems in central California is you want about 75% of the pool's surface area in unglazed solar collectors, or 50% glazed. Roughly 90% of the heat loss from a pool is through the surface. At 10,000 gallons, if the average depth is five feet, the surface area would be about 250 square feet, so you would want about 188 ft sq of unglazed panels or half of the area, 125 ft sq of glazed collectors. A six foot coil of tube is about 32 ft sq and uses close to 300 feet of 3/4" tube.

    I agree with Bob, that you might not need a lot of solar collector area, but I might use your gas bill to determine what the load really is and size the solar accordingly.

    Yours, Larry

    ps. A pool cover will help big time!
  • matt_sunwaysolarmatt_sunwaysolar Member Posts: 61
    I'm in agreement with Larry's concerns. The heat collection from the 3/4" pipe is likely to be minimal. It may heat up in the sun, but I'd be surprised if the initial diverting of water through it doesn't cool it off right away.

    The square footage that pool panels offer will be much better and without major concerns about pressure drop. The cost of plastic pool panels being relatively low, I'd go that route if possible. Then you could use a diverting valve or a P/S piping method. Plenty of successful pool systems have been installed both ways.
  • GordyGordy Member Posts: 9,523
    edited December 2015
    It won't do squat. I tried this with 300' of black garden hose on a 165* black rubber roof. By the time I slowed the flow enough to get decent hot water out of the hose it was a trickle. I would have had more production if I was to let cattle wade, and urinate in my pool.

    A solar pool cover will do far more with less hassle, and prevent evaporation that is the bulk of heat loss to the pool.
  • Mark EathertonMark Eatherton Member Posts: 5,843
    Google "Liquid Pool Cover"... Cut your bill by up to 80%!

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • hot_rodhot_rod Member Posts: 13,475
    Un-glazed collectors have a narrow operating range, usually 5- 10° of ambient temperature is the sweet spot, below that performance drops quickly.

    75- 80% is the rule of thumb I have always used for array size to pool square footage, as Larry suggested.

    Wind across the surface really rips heat also, a cover, fence or shrub row will greatly reduce that loss.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Paul48Paul48 Member Posts: 4,492
    I'm gonna pick up some of that liquid pool cover.....Thanks ME. Twenty bucks a month is a drop in the bucket, for the money pit. :smile:
  • vaporvacvaporvac Member Posts: 1,520
    @Paul48 , we have very hot summers here with hot nights. However, the liquid pool cover helps extend the season. Mine comes in a ball,lasts for maybe a month, and wasn't expensive at all. It's also nice that it doesn't require any daily handling.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • GordyGordy Member Posts: 9,523
    I have used it it works.
  • Paul48Paul48 Member Posts: 4,492
    Yeah.....I see those, and they're not expensive. We have an above ground pool, and the solar blankets are a real pain. As for extending the season....maybe make the font end of the season more comfortable sooner, but on the back end, once the air temperature gets cooler, nobody wants to go in anymore. Woke up this morning to some slush on the ground. It's the first time this winter it's been cold enough. I had to put the lawn chairs back out, and we spent Christmas day outside.
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