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Anonymous Poster

Heater

10/16/2010 11:40 AM

hi, i have a heater designed for 220 volt.

what will happen if i aplly 440 volt ac across its terminals????
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JohnDG
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#1

Re: Heater

10/16/2010 11:45 AM

You'd better have a fire extinguisher handy.

In practice, it should be internally protected by an overcurrent and/or overtemperature device, but the heater element may fail if these do not act quickly enough.

If it is not correctly protected, see my first sentence.

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kramarat
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#2

Re: Heater

10/16/2010 12:18 PM

Why not just step down your 440 to 220 and use it the way it was designed to be used?

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wareagle
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#3

Re: Heater

10/16/2010 1:00 PM

Smoke, fire, explosion, injury, law suit.
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Icarus
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#8
In reply to #3

Re: Heater

10/17/2010 12:06 PM

You forgot: death, destruction, mayhem and the end of the world as we know it.
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JRaef
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#4

Re: Heater

10/16/2010 1:19 PM

Resistance heaters (assuming such) are simple.

You know the watts of the heater right? (you didn't say)

You know what the voltage should have been.

Use Ohm's Law to solve for resistance based on knowing voltage and wattage.

Apply resistance to higher voltage to get new current.

Apply higher voltage and new current to get new wattage rating.

Example: 1000W heater, 220V nameplate rating.

Ohm's Law, R = E2/P so R = 220V2 / 1000W = 48.4ohms

I = E/R so with 440V, I = 440/48.4 = 9.09A

So new P = E*I, P = 440*48.4 = 4000W

Chances are any devices (such as ceramic stand-offs and/or small metal brackets) holding the heater and the wire connecting it may not be able to handle the extra heat. Plus because the physical size of your heater unit remains the same, your "watts density" quadruples, further stressing the mechanical components and probably the fire protection rating of heat shielding etc. In other words, what was designed to be a 1000W heater has now become a 4000W heater! It wasn't made to be that hot.

Don't do it.

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JohnDG
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#5
In reply to #4

Re: Heater

10/16/2010 5:03 PM

... or to state the same without exemplary numbers,

Power = (Voltage)2 / Resistance.

The resistance doesn't change, so doubling the voltage means the power goes up x 4.

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#6

Re: Heater

10/16/2010 7:59 PM

If you have a second identical 220v heater, you can wire them in series on 440v, and each will use 220v of that.

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#7

Re: Heater

10/16/2010 10:02 PM

If you are lucky a protection device will kick in and remove power before any damage occurs. If you are unlucky you will have a fire and broken heater on your hands.

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#9

Re: Heater

10/19/2010 4:32 AM
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