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Where to place pool heat exchanger

SnowmeltSnowmelt Member Posts: 1,195
Could you place the pool heat exchanger by the pool pump or by the boiler.......
The pool pump is about 60 feet from the house and another 20 feet from the boiler.........
there is access ( or should I say) I can burry the tubbing below grade, so the question is how deep, it’s only for summer and I can drain it during the winter. I am a viega guy so I mostly be using viega pex until I get in basement then transitioning back to copper.

Comments

  • Jamie HallJamie Hall Member Posts: 12,954
    In terms of the hydraulics, nothing much to be said for either placement, for or against -- one way or another you will need to pump pool water to the exchanger and boiler water to it.

    That said, there might be some merit to putting the exchanger near the boiler, since the boiler water will be hotter and thus you will have less heat loss (short run of hot pipe and long run of warm, vs. the other way around). But there's not much in that, either.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,978
    If you are running pool water, I would avoid copper. Some type of plastic (pex or pvc) is best. Chlorine pool water doesn't get along with really any metal very well, 400 series stainless or titanium, being the only acceptions to my knowledge.

    I'd be tempted to put the HX inside, that way you dont have boiler water outside underground where it would either freeze of need to be drained and fresh water added to the boiler every spring when its refilled. Pipe it directly into a floor drain, I really hate pool water, it turns everything nasty.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • SnowmeltSnowmelt Member Posts: 1,195
    Ok, so if I go inside, that’s what I want to do , what material do I use to go to the pool heater...... pvc then just glue it or should I run pex , if I can get to the pool with one roll, so there’s no elbows or couplings
  • kevink1955kevink1955 Member Posts: 71
    Just keep in mind if you put the exchanger in the basement any leak on the pool water side has the potential to fill the basement with pool water, PVC into the exchanger has the potential to melt if the exchanger runs without pool water circulating. Ask me how I know Lol, at least my exchanger was outside
  • SnowmeltSnowmelt Member Posts: 1,195
    Could we get shut off that closes when water hits the floor ?
  • ZmanZman Member Posts: 5,872
    My vote would be near the pool and away from the house.

    Heating components are of higher quality than pool parts and because the heat side is a closed system, you are less likely to have troubles there.

    The pool side usually requires higher flows and is an open system. The typical pool piping is lower quality and the system pressure is usually very low resulting in pump cavitation if one is not careful.

    Your trench presents a problem in either case. with your 200K/Btu boiler, you probably need 1 1/2" pex and it needs to be well insulated. In the winter either drain it back or glycol the boiler system. If you run the pool piping to the house you probably will need 3" piping to mitigate the risk of pool pump cavitation.

    Do you have your required flow rates for the pool?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Paul PolletsPaul Pollets Member Posts: 3,297
    I like to put the HX or FPHX near the boiler. Use unions, isolation valves, thermometers and drain cocks on both sides. For 16K gallon pools and larger, the piping to the pool and filter should be PVC and will be 11/4 to 11/2". Either type of HX works well, if sized properly. Even with a 2 stage 300K boiler, the pool would only rise 1 degree per hr. on startup.
  • ZmanZman Member Posts: 5,872
    edited July 8
    I would usually design the pool side a full changeover every 6 hours. A 16,000 gallon pool / 6 (hours) / 60 (min) gives you a flow rate of 44.4 GPM. I would size for a minimum of 2" on the discharge and 3" on the suction side to prevent cavitation.

    From a heating point of view, the pool side of the heat exchanger would be 200,000 btu/hr / 500 (constant) / 44.4 (gpm) would yield a delta T of 9 degrees.

    On the boiler side of the heat exchanger, you would be looking like this: 200,000 btu/hr / 500 / 30 (delta) = 13.3 GPM. 1.25" or 1.5" pex would do just fine depending on the circulator and the run.

    You can of course change the parameters. That math will stay the same.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ZmanZman Member Posts: 5,872

    I like to put the HX or FPHX near the boiler. Use unions, isolation valves, thermometers and drain cocks on both sides. For 16K gallon pools and larger, the piping to the pool and filter should be PVC and will be 11/4 to 11/2". Either type of HX works well, if sized properly. Even with a 2 stage 300K boiler, the pool would only rise 1 degree per hr. on startup.

    This is nonsense. A 16,000-gallon pool has a water weight of 16,0000 x 8.34 = 133.440 lbs. Assuming that a BTU still equals the amount of energy required to raise one pound of water one degree Fahrenheit, only 133,440 btu's will be required to raise the temp one degree. If the boiler has an output of 300,000, it will raise the temp 2.25 degrees per hour.

    Granted the efficiency of the boiler and the heat loss of the pool to the ground and evaporation needs to be factored in, but the math doesn't lie.

    If you are going to entertain the idea of running 44.4 GPM (or even 22.2 gpm) though a 1 1/4" pipe over the equivalent of 240 linear feet (plus the heat exchanger) in an open system with a pump sitting above the level of the pool, I would suggest stocking up on spare impellers (and earplugs).
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    Solid_Fuel_Man
  • SnowmeltSnowmelt Member Posts: 1,195
    Bad news, he’s going to install an electric heat pump / pool heater. How ever I still have the boiler for inside the house which I am going to install a 110 Navien Boiler only
    Zman
  • SuperTechSuperTech Member Posts: 1,344
    Honestly I think the electric heat pump pool heater is a better idea. It eliminates a lot of the problems that would be associated with using the boiler, and makes your job a little bit easier. 😉
  • SnowmeltSnowmelt Member Posts: 1,195
    You got that right
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,978
    Almost all pools I see are heated with direct fired gas pool heaters.

    If I ever wanted yo heat a pool at my own house.....I'd use a heat pump inside, and get the benefit of "free cooling" in the house. Basically dump the heat from the house into the pool. Also solar for pool temp maintenance would likely work out well.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    ethicalpaul
  • ratioratio Member Posts: 2,496
    Natatorium air conditioning is a real thing, with several big players. Around here, I've installed Seresco, Desert Aire, PoolPak, & maybe others. Here is a comprehensive-looking design guide, here's another. Many blogs to read as well.

    It appears that most/all can be ordered with a water heating coil to reject heat back in to the pool. I can't imagine not using something like that, but I've installed more than one where the engineer ordered that option but didn't use it. <shrug>

  • EYoderEYoder Member Posts: 60
    edited July 10
    I've hooked up several pools to outdoor wood boilers.
    I put the tube and shell HX near the pool. Use CPVC threaded nipples to connect PVC unions to HX in case it gets too hot.
    Route power to the pump on the boiler through a controller powered by the same circuit that the pool pump runs on. Basically make it fail safe as possible.
    Insulated pex run underground with unions at the pool HX. Pex won't burst in the winter, so no need to drain. Boiler side typically has a large delta T to move a huge btu load, but it's much easier and safer than piping PVC inside.
  • motoguy128motoguy128 Member Posts: 119
    Worth a reminder that in this case “PVC” is pressure rated PVC not DVW pipe. HUGE difference there. The fittings have a lot more engagement and tighter tolerances. I ran across a pool pump with DVW once. I went to open a ball valve and a whole section of pipe fell apart with water gushing everywhere.

    Lad scalpers had moved a gas pool heater and the reconnected the piping afterwards.
  • HenryHenry Member Posts: 968
    I use titanium HX for pools and PVC sch 40 pipes with flanges. Heat pump pool heater lasted 6 years at my friends house. Put in a propane Raypack 20 years ago that is still running.
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