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Thread: Millivolt or Electronic Pool Heater?

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    Millivolt or Electronic Pool Heater?

    We are having an inground installed this spring. We had thought of getting an electronic gas heater, the Hayward H250. The pool builder has strongly suggested the millivolt model. He justified his suggestion by indicating that while electronic are easier to operate, the millivolt model is much easier to fix, repair etc. Basically he said the electronic model while nice, has more equipment that can go wrong and that if the electronic board goes it will be quite expensive to repair. So, while we had originally wanted an electronic heater, if there is an air of truth to his concerns, that would be enough to sway me. BTW, we have a gas stove that is electronically controlled. The board went and it cost us $800 to fix.
    16 X 32 Vinyl. Hayward aqua rite salt system, T -15 cell. Hayward H250 gas heater, Hayward 1HP superpump.

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    spishex's Avatar
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    Re: Millivolt or Electronic Pool Heater?

    Depends on how handy you are. If you take the labor out of the equation he's right, but millivolt heaters can be very flaky and cost you multiple service trips in a year to replace those cheap parts as they age. Since they're only running on a tiny tiny amount of electricity, any little hiccup in the wiring will shut it down. If you're good with a volt meter you can track down and fix any problems pretty easily.

    And they've still got expensive parts. The temperature control assembly, for instance, can easily go over $200. Then there are all the ticky tacky parts: fusible link, hi limits, pressure switch, pilot generator, etc. With electronic heaters you've got circuit boards that run in the $100-200 range and ignition controls which are a bit more, but they don't go bad nearly as often. The most expensive part is the same on both: the heat exchanger.

    In both cases, your gas bill will far outweigh any maintenance costs, so I'd look at efficiency first and foremost. Just so happens that most millivolt heaters are on the bottom end in this regard.

    These would be my top three in terms of efficiency:
    - Laars HiE (Crazy expensive)
    - Lochnivar EnergyRite (Good price for the efficiency, but not as common so parts might be harder to find)
    - Pentair MasterTemp (Sta-Rite MaxTherm) (Same guts in both heaters. My favorite. These things are pretty 'trouble free'.)

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    Re: Millivolt or Electronic Pool Heater?

    Thanks for the reply. I am not hand AT ALL. Zero. In any case, he will sell me either model, and he suggested Hayward because he has an agreement with them that provides for a 3 year year warranty instead of the standard 1 year. My knowledge level of heater and pool equipment generally is admittedly low, so this will likely sound like a stupid question:
    With a millivolt heater, once the water temp reaches say 80, the heater shuts off. When the water temp drops below 80, does a millivolt heater come back on automatically, or is it so manually operated that one has to go over to it and turn it back on manually? Basically, if I turn the knob to the temp I believe to be 80 and leave it, does it maintain 80?
    16 X 32 Vinyl. Hayward aqua rite salt system, T -15 cell. Hayward H250 gas heater, Hayward 1HP superpump.

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    spishex's Avatar
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    Re: Millivolt or Electronic Pool Heater?

    Yes, both models will satisfy the thermostat's demand for heat continuously until they are turned off. The only difference is the millivolt model ignites using a standing pilot and derives it's power from a thermopile, or pilot generator, which uses the heat from the pilot light to generate a small electrical current. The electric model uses 120-240v for ignition, either by sparking and igniting a pilot on demand or by using a hot surface ignitor which just looks like a red hot heating element when on, and uses a low voltage (12-24v usually) circuit for the safety and control circuitry.

    The standing pilot will run at between 1,000-2,000 BTU's 24 hours a day which will cost you a few bucks whether you heat the pool or not, and since it's running on a very low voltage DC circuit, any loose connection or slightly flaky component will require a firm, swift kick or a service call.

    I'm not sure about the other two, but the Mastertemp/Maxtherm already comes with a 2 year warranty standard. But again, most heaters are pretty reliable the first few seasons. Efficiency and proper sizing (and good water chemistry for your heat exchanger's sake) are what will save you money in the long run.

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    Re: Millivolt or Electronic Pool Heater?

    I would recommend you go with the electronic model for these reasons.

    1. A standing pilot light is very energy inefficient.
    2. A standing pilot light requires you to be handy to light it should it go out.
    3. Heater electronic control boards are very commo. And almost a commodity many times with 3rd party manufacturers making ones less expensive than the original.
    4. A friend of mine does HVAC. He says these types of stories about one type being more expensive to repair than another has less to do with truth and more to do with existi g equipment inventory sitting in the builders shop. So my guess is that the builder has or has I expensive access ( think closeout) to a millivolt unit but not an electronic unit.

    But by all means, do buy the most efficient unit you can afford.

    I have a Laars 400,000 btu model and to heat my 24,000 gal pool without any cover in TX to 80 degrees on a continual basis costs $20 each day in natural gas. So I put a solar blanket on and reduced the temp to 75 which has helped a lot.
    IG 24k plaster with overflow spa. Goldline PS-8 SWG. Tristar 0.75 HP filter pump, Polaris 280, large cartridge filter, 400k BTU NG Max-E-Therm HD, SR Smith Turbo Twister, Life Saver pool fence, ORP managed.

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    Re: Millivolt or Electronic Pool Heater?

    I tend to agree with leathur. The cost difference between the two should be less than $100. You do have additional cost in running electrical service to the electronic model, which the milivolt avoids. Electronic models give you a digital temp and troubleshooting display, too. If you have a pool/spa combo, electronic models permit temp settings for each seperately.

    Most of the "older" builders like the milivolt models because that's what they "know", and how to service them. Conversely, many main mainufacturers wish milivolt would just die a natural death, because parts for MV heaters are in a somewhat shorter supply, because of reduced demand, and because troubleshooting the MV is an art. MV heaters are "old technology".

    Both work well, and you can't really go wrong with either, IMHO. 8)
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