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Thread: hotspot heater

  1. Back To Top    #1

    Join Date
    Mar 2009
    nashville, tn

    hotspot heater

    Greetings all,
    I just bought a house that has a 18x36 vinyl in ground pool in the backyard facing due north. I am trying to decide on how to heat this pool. My previous pool had 8'x20' (total area) solar panels which worked ok except for the after the 6th year or so they started springing leaks. This house is 3100sq' with two story with 2 beds 1 bath and a bonus room upstairs with a lot of the lower living area with high ceilings open to upstairs. The upstairs heat pump unit is right beside the pool pump and filter at the rear of the house. To use solar I would have to build a pool cabana and install it on its roof. I would be able to use a max of 4 4x12 panels or 186'ft. Also to be honest, the wife is not interested in seeing a bunch of plumbing. I could hide it some but...

    I have searched for opinions on the hotspot heater. If you haven't seen one, it uses your existing ac run thru a heat exchanger to heat your pool. I think it will return the ac to normal operation when the pool reaches 94. I know the ac demand mirrors the pool temperature from beginning to end of the swimming/ac use season, but I wonder if this house might be a candidate. The house and pool receives full sun, no shade. The upstairs will be needing ac well before the rest of the house in the spring and well after the rest of the house in the fall due to the heat rising/proximity to roof/attic etc. and we can use the upstairs unit more than the downstairs unit.

    Here are some things to consider:
    The ideal pool temperature for me would be 90-94 in the evening.
    Increasing ac efficiency/decreasing electric bill would be an added bonus.
    I am estimating total cost for hotspot heater at $2500.
    Solar panels cost $1200 plus $1500ish for 16x14 cabana. (not counting my labor)

    There are a few things I have questions about:
    I would like to find a balance to cool the pool at night as much as possible to gain ac efficiency for cooling the house the next day while being able to heat the pool back to the 90's by sundown ish. The ac unit will be more efficient when the pool temp is coolest. I have never tried to cool a pool in the middle of the summer with a fountain running at night. How effective would that be? Any other suggestions on cooling pool at night? ( I know a solar panel works great!)
    I'm wondering how well this heater will work. Should it be comparable to a pool heat pump of comparable size in terms of btu's?
    I think it takes about 8.33 btus to raise one gallon of water one degree. So for my 25000 gal pool that would be 200,000 btus for one degree. I think my heat pump is a 5 ton unit. Running continuous cycle any idea btu per hour? Here's what the manufacturer says:
    "We estimate that on average, a full sun, low wind pool needs a net heating capacity of about 650 BTU per day, per sq. ft. of surface area. A typical 16 x 32 pool (512 sq. ft.) will need about 332,800 BTU per day of heating capacity. A little more, if in a windy or shady location. A heat recovery pool heater can deliver about 15,000 BTU per hour into the pool per ton of AC capacity. Therefore an average pool would need up to 22 “ton hours”, meaning a 5 ton AC unit would need to be running for 4.4 hours per day, or a 3 ton AC running for 7.4 hours per day, and so forth. For extra large pools, or when using small air conditioners, we can provide a dual system that will use two AC units together on one pool".
    So for my application 75000 btus per hour for say four hours would be 300,000 btus. 1.5 degrees per day? Maybe i wont need the fountain except for extremely hot days? I can only guess how many hours per day the heat pump will be running. ( new house).
    So anybody have one of these or have first hand experience?
    Heat pump owners... how fast does your pump heat your pool?
    Yes, a little long winded today.
    Thanks for your replys.

    16286 gal. 16x32 grecian with 2 shallow ends deep in middle, liner, aquagenie, aqualogic p-4 t-15 swg, 8'x20' solar panels, 16mil solar cover, Hayward 1hp superpump, 2" pipes, Hayward Pro 300lb sand filter, built july 07.

  2. Back To Top    #2

    Re: hotspot heater

    I have a hotspot pool heater.

    The CONS
    1) Price is for a kit, you must buy additional parts and provide the labor $$$
    2) The engineering data is not exact, You have to build a balance coil which matches your condensing unit's coil volume. But the Engineer will only get you close to the proper size, the proper size will finally be determined by trial and error.
    3) Pool needs heat when the house does not need cooling.
    4) Only works when the AC is running.
    5) I do not see any increase in AC efficiency
    6) No safety devices are included in the kit. Standard pool heaters have many safety devices.
    7) Must route temperature sensors behind the pool lights.

    The PRO's
    1) I can brag about my AC heating the pool
    2) If I have a party, turn the AC down real low, and wait four hours, the Spa will start to get warm.
    In design phase-
    Considering salt vs ozone
    60' x 9' lap

  3. Back To Top    #3
    linen's Avatar
    Join Date
    Jul 2010
    Twin Cities, MN

    Re: hotspot heater

    You can use the google search near the upper right of each tfp page and put in search terms such as "air conditioner heater" or "hotspot heater" and get some info/feedback. Basically it is as jerryt mentioned, in most instances it is not a "hot" idea. Most people do not need to heat their pool often when they need air-conditioning.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  4. Back To Top    #4

    Join Date
    Mar 2009
    nashville, tn

    Re: hotspot heater

    Thanks for the replies. This is exactly the kind of first hand experience I was looking for. Jerryt it sounds like you are not exactly in love with your hotspot. Linen I did type in hotspot in the search but saw no threads where someone who actually has one chimed in, only opinions of if they might work or not... I will be looking more closely at another solar project. Thanks guys.
    16286 gal. 16x32 grecian with 2 shallow ends deep in middle, liner, aquagenie, aqualogic p-4 t-15 swg, 8'x20' solar panels, 16mil solar cover, Hayward 1hp superpump, 2" pipes, Hayward Pro 300lb sand filter, built july 07.

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