can I convert a 220V heater to 120V

[brewster]

I have a space heater that has a 220V power cord
and I would like to know if it is possible to change
the plug to run on 120V use, It doesn't have a blower on it
And this will be used in my garage, I don't have a 220 outlet
And I will only be useing it temperary

[HayZee518]

you can use 120 volts on it but the output would be halved. the current draw would be twice what it is at 220. say at 220 it puts out 3000 watts. 3000 divided by 240 gives 12.5 amps 3000 watts divided by 120 volts equals 25 amps. watts equals volts times amps. amps equals watts divided by volts.

[brewster]

So Are we talking fire hazzad Than, If I use It for a long length
of time, I don't want to rigg up something to cause a fire
( just want to be safe )

[HayZee518]

you won't cause a fire if you change the cord and plug to accept 30 amps that means 10 gauge wire with a 30 amp 120 volt plug. its circuit would have to be also 30 amps with 10 gauge wire on a 30 amp breaker.
how many watts does the nameplate say? can you go into the chat window? I can talk to you there.

[brewster]

You've Answered what I really need to know
And I thank you for your time

[Speedy Petey]

A heater like this is a resistance element. This means the lower the voltage the lower the output for a given element.

Let's say your heater is 3000 watts @ 240v it would be 12.5 amps. This is 19.2 ohms.
That same 19.2 ohm element would be 6.25A at 120v and 750 watts.

If you see the box a heater comes in you will always see a lower wattage for a lower voltage in the same unit. Same thing with an electric range. The wattage is always lower at 208v than at 240v.

A 3000W element designed for 120v has a resistance of 4.8 ohms and would run at 25 amps.

[596]

If your heater was orginally designed with the option of running on 120 or 240, then the description of more current would be correct. What they do on that type of unit is have two elements, and you jumper them so they are in series to run 240, and you jumper them so they are in parallel to run 120. So in the latter case, the current is double.


But if the heater is a single element, then connecting it to 1/2 the rated voltage will yield 1/2 the current draw, and 1/4 as many watts.

[dha]

You are the only one who got it right. If you apply half the voltage to the same resistance you get one-fourth the power, not half the power.
The power is equal to the square of the current times the resistance. This heater could be plugged directly into 120 volts... but it would not produce much heat. It may be safe, but not very useful. If it had a fan, that would be another wrinkle, because the fan would probably not spin very fast - if at all.

[Speedy Petey]

If you apply half the voltage to the same resistance you get one-fourth the power, not half the power.

Exactly. 750 is 1/4 of 3000.

Let's say your heater is 3000 watts @ 240v it would be 12.5 amps. This is 19.2 ohms.
That same 19.2 ohm element would be 6.25A at 120v and 750 watts.