What's the difference between 240 volts and 220 volts?

heaters

Taking longer to heat is what I meant by losing capacity. A 4500 watt, 240v element will draw approximately the same amps at 208 volts, but the wattage will be less, approx. 3800 watts.

Furd said:

You're all wrong!

Click to expand...

I beg to differ.

Since there are 3414 BTUs per kilowatt it is easy to see that at 120 volts the heat output is 3840 BTUs and at 240 volts it is 15,363 BTUs or that at the lower voltage the heat output is, like the wattage, 1/4 of the design output.

Click to expand...

or, as I said earlier,

Mikey said:

Actually, it's a voltage-squared relationship, I think.

Click to expand...

I want to add a tankless

I was reading your post and I understand what you are saying about 208VAC vs. 240VAC. The tankless water heating unit I was looking at needs 240VAC to operate but at 208 it will reduce the units ability by 25%. I am using it at the kitchen sink & dish washer. would you recomend not doing that? and will it not do what I need? I am moving my kitchen to an outside wall from the middle of the house and have to make the run outside and around the house which is a block home on a slab (1950s build home in Florida).

Thank you for any advice you can give.

power

You are misstating my answer about the 10% power differential. It has nothing to do with a GFCI, it is whether a 240 volt device will operate properly at 220 volts. It would but 208 volts would be outside its tolerances.

You also intentionally misunderstand the statement about water heater capacity, i.e., recovery not volume. A 4500 watt/240 volt element only produces 3200 watts at 208 volts. Meaning it takes approximately 20% longer to create the same volume of hot water. There would also be a reduction if it were used with 220 volts. which is why the elements in a water heater should be ordered according to the power available for the best usage.