120V and a 240V baseboard heater

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Old 10-17-19, 05:40 PM
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120V and a 240V baseboard heater

Hello and thanks in advance for any help you can provide. I was looking at an electric baseboard installation by the handyman at my friendís apartment. If the heater circuit is 120V with a 20A breaker and the handyman replaced a broken 120V 1000W electric baseboard heater with a 240V 1000W electric baseboard heater will this create any other electrical problems besides less heat? The handyman said you will get some heat but the installation is not dangerous. The 120V 1000W replace baseboard heater was ordered and we are waiting for it. In the meantime the handyman installed the 240V 1000W baseboard heater so we could have some heat.
 

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10-17-19, 06:21 PM
Luke M
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Only 1/4 the heat (250W), but yeah, should be safe. Or you could just turn on a couple lights. :-)
 
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Old 10-17-19, 06:21 PM
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Only 1/4 the heat (250W), but yeah, should be safe. Or you could just turn on a couple lights. :-)
 
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Old 10-17-19, 08:29 PM
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Heater is a resistance which is a constant. Since e = ir and you half the voltage, the current is halved. Since power is ei and both were halved, you get a fourth of the power. There is no problem with the temporary heater except it will take more time to heat the area.
 
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Old 11-13-20, 07:27 AM
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Thanks for the responses. Here is my late update. We got the 240V heater installed and the yes, definitely more heat. Thanks again.
 
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Old 11-13-20, 08:38 AM
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Originally Posted by traneXL80by
the handyman replaced a broken 120V 1000W electric baseboard heater with a 240V 1000W electric baseboard heater
A 1000 watt heater, by definition puts out the same amount of heat, whether it's 120v or 240v.
Doubling the voltage halves the amperage, but won't put out more heat.
It WILL probably heat up more quickly.

V=O x A
W=O x A x A
Take W= (O x A) x A
Replace (O x A) with V, you get W = V x A
To find out amps divide both sides by V and you get W / V = A

1,000 Watts / 120 Volts = 8.33 Amps
1,000 Watts / 240 Volts = 4.17 Amps

Originally Posted by traneXL80by
will this create any other electrical problems besides less heat?
Possible code violation unless the 'handyman' re-tags the white 'neutral' to red 'hot' to indicate that it's now being used in a 240v circuit.
 

Last edited by Hal_S; 11-13-20 at 08:54 AM.
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Old 11-13-20, 09:03 AM
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You temporarily put a 240 volt heater where a 120 volt heater of the same wattage should have gone.

The 240 volt heater will not draw the exact current so as to consume its rated 1000 watts. How much it does draw requires some calculation involving the resistance versus temperature curve of the heating element. +1 No harm no foul.

But do not try this at home: Going the other way, running a heater or anything else on too high voltage like a 120 volt heater on 240 volts.
 
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Old 11-13-20, 07:05 PM
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A 240v 1000 watt heater running on 120v is 25% of the rated wattage or 250 watts of heat output.
 
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Old 11-13-20, 08:44 PM
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Oh, we're assuming the 240 heater is running at 120v?

A 1,000 Watt heater designed for 240V is around is 57.6 Ohms and draws 4.16 amps at 240 volts.
Watts = (Volts x Volts) /57.6 Ohms.

Drop that voltage down to 120V it only draws 2.08 Amps and per W=O x A x A it's 57.6 x 2 x 2 and it
only produces 250 watts
 
 

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