240V electric water heater on 120v circuit

[miscmail1560]

I had to replace my electric hot water heater a few days ago because the dip tube was disintegrating. It was 14 years old, so I felt it was time for a replacement. The plumber came out and replaced it with a comparable 50-gal electric water heater. Later that evening, I discovered that we were not getting enough hot water. I called the plumber back out. He determined that the power input into the hot water heater was only 120V, not 240V. The original HWH was 240V, and it met our needs. My questions are:
1. Are there any 50-gallon hot water heaters that are 120v?
2. Can a 240v hot water heater run on 120v?

I am selling this house soon, so I don't really care about long-term efficiency. I want to minimize my current expenditure, but I don't want to end up with something that will fail a house inspection.
Any advice will be greatly appreciated.

[Gary Swart]

You apparently had a 120v water heater, so the answer to #1 is yes. You now have a water heater that requires 240v, and as you have found it doesn't work too well. My advice is to run a 240v circuit. It's hard to say how difficult this would be, often when a water heater is in a basement and the breaker box is down there also, it's really quite simple. I'm surprised a plumber would not have recognized the problem when he did the installation. Perhaps you had a handyman instead of a plumber?

[Speedy Petey]

1) I SERIOUSLY doubt it!

2) NO.

I would check the circuit run to the heater. Tell us what size and type wire it is and what breaker it is on.

[Mike Swearingen]

miscmail1560,
If your water heater circuit is 240v, it should be with 10/2-with-ground wiring from a 30 amp double breaker.
How did that plumber test the voltage? At the circuit wiring connection or at the elements?
Did he completely fill the water heater before turning the power back on?
Is the temperature set as high as the old heater?
Mike

[Bob NH]

You can't use a 120 Volt circuit to get the required energy into a 240 Volt heater. I suspect that the plumber didn't get it hooked up correctly.

Almost all standard heaters use two elements, each 4500 Watts, that are controlled so that only one is on at the same time. If the top temperature is low then the top element has priority. If the top temperature is OK then the control switch sends the power to the lower temperature control.

You need someone who has knowledge and a meter to diagnose the problem. If the plumber knew what he was doing he would have done that and he would not have installed a 240 Volt heater on a 120 Volt circuit. A 120 Volt circuit will provide only 1/4 of the heating power of a 240 Volt circuit, which would cause you to have insufficient hot water.

SOLUTION:
If the wires are 10/2 with ground as should be the case with almost any heater, then they can be connected to a 30 Amp 2-pole breaker and connected to the heater. That should be done only by someone who knows what they are doing.

The heating elements should be checked to be sure that the plumber didn't damage anything in the process. However, a professional plumber should know enough to put water in the heater before turning it on. If he accidently burned out an element by not putting water in first, he may be now blaming the problem on a "120 Volt circuit" to avoid admitting his error.

[Cass]

Is the breaker going to the heater a 2 pole breaker (fat one) or is it a single pole breaker (skinney one)?