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Thread: Electric Heater Question

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    launboy's Avatar
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    Electric Heater Question

    I've seen some electric spa heaters that are only 1500 watts(1.5Kw) and 120 volts. How uch heat will this thing actually put out? Will it be enough to heat a 400 gal. hot tub a couple of degrees warmer? Say, the last 5 degrees to get it to 102*?

    I've also seen Intex 3Kw electric heaters. These run on 240 volts though. They are pretty much only available in the UK though. First, will this put out enough heat to heat the hot tub? Also, can I just cut off the European plug and wire it straight to a 240v switch or timer?

    Thanks,
    Adam
    18' x 42" Intex Easyset Pool, with 16' x 52" deep end in the middle. Approx. 5500 Gal.
    Hayward Power-Flo LX 1 HP, 100# Jacuzzi Brand Sand Filter(Piped underground so it looks nice) 8)
    3 - 2' x 20' Solar Pool Heater Panels(roof mounted)
    Goin' on 9 summers...NOBODY thought it would last this long.
    Buried Portable Spa sharing pumps and water with pool (Almost complete project)

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    spishex's Avatar
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    Re: Electric Heater Question

    Quote Originally Posted by launboy
    I've seen some electric spa heaters that are only 1500 watts(1.5Kw) and 120 volts. How uch heat will this thing actually put out? Will it be enough to heat a 400 gal. hot tub a couple of degrees warmer? Say, the last 5 degrees to get it to 102*?

    I've also seen Intex 3Kw electric heaters. These run on 240 volts though. They are pretty much only available in the UK though. First, will this put out enough heat to heat the hot tub? Also, can I just cut off the European plug and wire it straight to a 240v switch or timer?

    Thanks,
    Adam
    I have a 120v heater on my tub, but I wouldn't recommend it, especially not with 400 gallons. It'll get you there, but if you've got a few people splashing around in it, you'll lose heat fast. I didn't have a choice with my installation. The UK product might work, but keep in mind it is designed to work at 50hz instead of 60. That probably won't make much difference in a non-motorized piece of equipment like a heater, but that's just my guess.

    The bigger question is why are you avoiding the standard 5.5kw?

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    launboy's Avatar
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    Re: Electric Heater Question

    I am avoiding the standard 5.5 Kw because I don't have 220 v. wiring in the garage(I think, there's a mystery wire i should check) and my parents don't want to pay to have it installed.

    Is losing heat while in use a big problem with hottubs? I never thought about it but I guess all those bubbles would take heat with them.

    Thanks,
    Adam
    18' x 42" Intex Easyset Pool, with 16' x 52" deep end in the middle. Approx. 5500 Gal.
    Hayward Power-Flo LX 1 HP, 100# Jacuzzi Brand Sand Filter(Piped underground so it looks nice) 8)
    3 - 2' x 20' Solar Pool Heater Panels(roof mounted)
    Goin' on 9 summers...NOBODY thought it would last this long.
    Buried Portable Spa sharing pumps and water with pool (Almost complete project)

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    spishex's Avatar
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    Re: Electric Heater Question

    Ok. So you'd be better served with a standard issue heater than going for the 3 kw deal because that would end up being less than 1.5 kw when hooked up to 120v.

    Also keep in mind that all 240v heater elements are convertible to 120v, but not the other way around. So if you go ahead and get a standard 5.5kw assembly, you can run it with L1 and Neutral for now and hopefully get a service upgrade in the future.

    I assume if they don't want to run 220v they don't want to run a gas line either?

    The heat loss can be dramatic. Let's say your tub is at 100 and it is 50 outside, and your tub is about 8' x 8'. The heat transfer from the surface of the water to the ambient temperature in one hour is about 16,000 BTU or 4.7kw.

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    launboy's Avatar
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    Re: Electric Heater Question

    Wow, 16,000 BTU/Hr? That's quite a bit. FWIW, the spa is a 6' dia. circle.

    Yeah, running a nat. gas line back isn't an option(I've already asked). Right now I really want to find a small used propane heater. I can just run that off tanks which I don't mind carrying. I'm also considering making my own heater out of a car radiator(brand new, just not being used) and our old grill which we still have. I just don't know about corrosion issues with pool water in a car radiator.

    Thanks,
    Adam
    18' x 42" Intex Easyset Pool, with 16' x 52" deep end in the middle. Approx. 5500 Gal.
    Hayward Power-Flo LX 1 HP, 100# Jacuzzi Brand Sand Filter(Piped underground so it looks nice) 8)
    3 - 2' x 20' Solar Pool Heater Panels(roof mounted)
    Goin' on 9 summers...NOBODY thought it would last this long.
    Buried Portable Spa sharing pumps and water with pool (Almost complete project)

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    spishex's Avatar
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    Re: Electric Heater Question

    You won't be the first:

    http://www.redneckpoolheater.com/


    Good luck!

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    launboy's Avatar
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    Re: Electric Heater Question

    Yeah, I saw that link a while back. There is also a link on his site to another, this one : http://www.coalmont.ca/data/Hottub_2006.html This guy used his heater to heat a hot tub. This is pretty much exactly what I want to do. Thing is, by the time I've bought all the copper, i'd have spent enough to buy a "real" heater.

    Thanks,
    Adam
    18' x 42" Intex Easyset Pool, with 16' x 52" deep end in the middle. Approx. 5500 Gal.
    Hayward Power-Flo LX 1 HP, 100# Jacuzzi Brand Sand Filter(Piped underground so it looks nice) 8)
    3 - 2' x 20' Solar Pool Heater Panels(roof mounted)
    Goin' on 9 summers...NOBODY thought it would last this long.
    Buried Portable Spa sharing pumps and water with pool (Almost complete project)

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