240V water heater run on 120V

[EmjayMaine]

I have a 6 month old Rheem RTE13 240V tankless water heater that worked fine with no issues. I no longer needed it so I gave it to my brother as he had to replace his 40 gal one. He plumbed it and wired it himself. He called me up to say that when he runs it as soon as there is demand the breaker trips. I asked a bunch of questions about the wiring to find out he wired it up to a 120V circuit instead of the required 240V. So he broke down and got an electrician to install a new 60 amp 240V dual pole breaker and new 6/2 wire. Now it all works fine but he says the lights flicker in the house when the water heater kicks on.

Is it possible the heater was damaged from running it on 120V? I never had any problems with it when I used it.

Thanks in advance,

Michael

 

[Jadnashua]

As long as the electronics that control it weren't fried, the lights flickering is a result of marginal power available in the whole house. There may be a loose connection somewhere...I'd double-check the main leads to the panel. An older panel might have corrosion issues, creating a poor connection.

Personally, an electric tankless would not be my first choice for a WH. Might work in the southern parts of the country where the incoming water is quite warm, but in most places, it's not a great idea the way the average American uses hot water. That tankless system has the equivalent of about 40KBTU, without the tank and storage. It will not provide much of a temperature rise when there's much flow rate.

 

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[EmjayMaine]

As long as the electronics that control it weren't fried, the lights flickering is a result of marginal power available in the whole house. There may be a loose connection somewhere...I'd double-check the main leads to the panel. An older panel might have corrosion issues, creating a poor connection.

Personally, an electric tankless would not be my first choice for a WH. Might work in the southern parts of the country where the incoming water is quite warm, but in most places, it's not a great idea the way the average American uses hot water. That tankless system has the equivalent of about 40KBTU, without the tank and storage. It will not provide much of a temperature rise when there's much flow rate.

Thanks for your reply. It would seem that the water heater is working fine so I doubt the electronics were fried. I think my brother needs to get his electrician back to check the panel and maybe upgrade it.

I understand your thoughts about the type of heater, my own plumber said the same. However it was the only viable choice I had since my boiler had failed and needed replacing and I needed a temporary solution and couldn't use anything but electric and had no space for a tank system. Surprisingly it worked out just fine - plenty of hot water and never running out. My brother is using it in his camp that only has one person there occasionally and only has two sinks and a shower. I expect it will work OK for his needs. If not then another solution will have to used.

 

[MikeQ]

Have him check the screw terminals for the main power feed to the distribution panel. Over time a thin layer of oxidation can form and reduce the ability of large amounts of electricity to pass, like a little kink in a garden hose. Sometimes just tightening up the screw connections is enough.

 

[MikeQ]

Surprisingly it worked out just fine - plenty of hot water and never running out. My brother is using it in his camp that only has one person there occasionally and only has two sinks and a shower. I expect it will work OK for his needs. If not then another solution will have to used.

My experience with electric on demand water has been very good after about three years. I replaced a standard tank water heater because I needed the extra space and the tank would run cold if too many people wanted to shower consecutively. It was only good for 3 showers because the incoming water is only 40-43 degrees, if I was using the dishwasher or doing sheets/towels on hot it could run cold after two showers. So I replaced the tank with a 28.8kW on-demand heater and haven't run out of hot water yet. It can handle two simultaneous showers because I have a heat recovery drainpipe on the upstairs shower that pre-heats the incoming water from about 42F to 91F before it enters the tankless heater. That measurement was taken with only the upstairs shower running, with two simultaneous showers the temperature rise would be about 29 degrees instead of 49 degrees due to the higher flow through the heat recovery pipe. But it still works great with two showers running simultaneously (which was my goal).

I have a third shower outside on a private deck but I can't run all three showers at the same time with adequate flow. But that's ok, it would be quite a coincidence for all three showers to be in use at the same time. Even with my old tank style heater this would not be possible (unless all showers were only about 4 minutes). Friday I took my shower outside. It was 32 degrees with an inch of snow on the deck. The water coming out of the showerhead was about 114F and, boy, did it ever feel good as it created a plume of steam like a hot spring geyser! Showering outside in the winter is a real kick!