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Thread: hot tub heating with heat pump?

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    hot tub heating with heat pump?

    Hi,

    I have an old hot tub which Im refurbishing. Im adding new pumps and a sand filter but need to sort out the heating.
    I live in a warm climate in Spain and wondered if a heat pump would be suitable as the electricity is so expensive (ie it would be cheaper due to the 4:1 cop). I havent seen a hot tub which uses a heat pump for heating so wondered what the down side is. The price of a heat pump is more expensive than an electric heater but I thought that in the long run the heat pump would be cheaper.

    Does anyone have any views / experience with this?

    Thanks in advance.

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    JasonLion's Avatar
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    Re: hot tub heating with heat pump?

    Most heat pumps can heat a spa, but they will do so slowly, and not nearly as efficiently as they can heat the pool. A heat pump get less efficient as the source and destination temperatures get further apart. There will be still be some electrical cost advantage compared to a resistive heater, but it will not be as large as if you were heating to a lower temperature (i.e. heating the pool).
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: hot tub heating with heat pump?

    thanks for repy jason. im no expert on this buy why does a heat pump struggle when the source and destination temperatures get further apart. i thought that the cop was all important and that the cop was greater when the ambient air temp is higher. if the ambient air temp is say 25 degrees C, is a destination temp of 38 degrees C not easily achievable for such a small volume of water in a hot tub.
    if a heat pump is not recommended, would an oil fired boiler be better when oil is much cheaper than electric?

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    JasonLion's Avatar
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    Re: hot tub heating with heat pump?

    The warmer the air temperature the better, and also the colder the target temperature the better for efficiency. Over the range of temperatures in question it is the difference in temperature between source and destination that determines the efficiency, not the absolute temperature. At very low or very high temperatures other factors come into play, but that doesn't matter here.

    As I already said, most heat pumps can heat a spa up to reasonable temperatures, it just takes a while. It is not a can it do it question, but rather a do you want to wait for it and pay for it question.

    Potential cost saving with oil heat is a question of the relative price of oil and electricity in your area, which unfortunately I don't know.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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