240v breaker serving two heaters

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Bought a house in April, now we're heading toward winter. On opposite sides of a wall are two fan-forced each rated at 240v. Both are connected to one 20/20 breaker. There's a fan issue with one of them so I want to replace it. The leads coming to it are WHITE and BLACK and BOTH are HOT when I touch them with a tester. I'm guessing that confirms there's 220v coming to the unit. First, is that correct?

The other thing is is there enough juice to run both heaters simultaneously or should each be on it's own circuit. In other words, is it wired correctly?

Thanks very much. Ken
 

Reach4

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Bought a house in April, now we're heading toward winter. On opposite sides of a wall are two fan-forced each rated at 240v. Both are connected to one 20/20 breaker. There's a fan issue with one of them so I want to replace it. The leads coming to it are WHITE and BLACK and BOTH are HOT when I touch them with a tester. I'm guessing that confirms there's 220v coming to the unit. First, is that correct?
Yes. The white wire being used as a hot should be marked in the breaker panel.

The other thing is is there enough juice to run both heaters simultaneously or should each be on it's own circuit. In other words, is it wired correctly?
Probably fine. It is not the voltage of the heaters that determine how much power gets drawn but rather it is the wattage or amp rating of the heaters.
 
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Yes. The white wire being used as a hot should be marked in the breaker panel.


Probably fine. It is not the voltage of the heaters that determine how much power gets drawn but rather it is the wattage or amp rating of the heaters.

Thanks, appreciate the response, Now I'm guessing this is not possible but the bathroom for this is small and doesn't require this much juice. Is it possible to convert one side of the 240v to 120v to install a smaller unit? There's no neutral in the box, just the two hots and the ground.
 

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You could change both to 120, but to change only one to 120 would require significantly different wiring.
 

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You can get lower-power heaters that use 240V.
 

Dana

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Resistance electric heating at typical NY electric rates would be out-of-sight expensive to run. Rather than replacing fan coil unit it might be worth doing something else, even if it's more expensive up front. Knowing more about the room size/windows/etc (or maybe even the whole house) would be needed to come up with reasonable suggestions.
 

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I'm not sure how to interpret that sentence without clarification of what is meant by "...that's...".

If you're just replacing the fan coil unit, first read the installation instructions of the intended replacement to verify that it's both functional and safe to operate without a neutral, and make sure the total wattage is no more than the one it replaced. Odds are pretty good that the original was significantly oversized for the actual heat load of the room, and going lower-wattage would draw less current while operating which keeps the wiring & breaker running cooler.

The 20A breakers at 240V would handle up to a combined 4800 watts (= 16,378 BTU/hour, roughly the typical heat load of 1000' of conditioned space @ 0F for 2x4 framed houses), but there is no reason to run it there if you don't have to. The 99% outside design temp in nearby Kingston is +2F, so short of doing a real heat load analysis, a typical room would do fine with 5 watts of heater per square foot of floor, would have reasonable margin at 7 watts per square foot, and would be ridiculously oversized at 10 watts per square foot. Living spaces are more comfortable if the heaters run longer (and quieter, for fan coils) duty cycles rather than cycling on/off multiple times per hour. A 2x+ oversized heater may satisfy the thermostat, but the goal is to satisfy the comfort requirements of the occupants, not the thermostats, which takes right-sizing it for the load.
 
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