My husband got an older outdoor jacuzzi from a friend that tears down houses
(excavator). We cleaned it and filled it up; the heater is piping that runs
around the motor. The only problem seems to be that it's not heating up
correctly. It's only 80 degrees after many hours of being on. The motor is
running and the jets work. Is this a lost cause?
Thanks in advance
If you want heat, I'd say yes. Lets assume your motor is 2 HP and is 80%
efficient. This means it draws about 2000 watts and is wasting about 400
watts in winding heat. A 400 watt heater is quite far from what you need to
heat a big tub of water. Most of the energy being drawn by the pump motor
will end up as heat in your water, as it is in most tubs. So even if all
2000 watts is heating the water, you're still way short of the 5000 to 10000
watts of additional heating that are typically installed in hot tubs.
I remember a few years ago when a friend told me about this great deal on a
small hot tub. She showed me the brochure and it mentioned how it used the
heat from the motor to heat up the water. It had a one horsepower motor and
I knew as an electrician that one horsepower is equal to 746 watts. 746
watts is not enough to heat a commercial coffee maker full of water in a
reasonable period of time. I advised her against it.
I'm sure these types of systems are good for keeping the motor nice and
cool, but definitely not adequate to keep a hot tub at 100 degrees or more.
When the top is off and the jets are running, the hot tub has a tremendous
amount of heat loss and the heater needs to be able to keep up.
If it is possible to install an auxiliary heater on the unit, then perhaps
you can turn it into a useful hot tub.
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