Generator for 50 gal hot water heater

What size generator do I need for a 50 gal hot water heater

Nothing for a older gas heater with a pilot light, less than 100W for a newer heater with electronic start and about 5KW for most 50 gallon tanks.

I have an 80 gallon electric heater that I run along with 2 refrigerators and a freezer, lights etc. with a 10KW welder generator. I do take care with I start things to stage them based on the length of the outage before I crank up the generator.

It really depends on how long you want to run the genny. I have some rental properties where the water is very hard. Don't plan to install a water softerner. The water heater would lime up and burn out the elements in a year or two. So I installed a new 30 gallon, 3500w electric and only wired it to 110 v instead of 220.

Cut the voltage in half, cut the current in half and the element is only getting 1/4 the power, 875 watts. Well, I can't remember the last time I replace a heating element. Tenants don't mind either. Guess they would if there were many people living there, but only one or two. BYW, it will take 4 times longer to heat the water.

So, lets say your 50 gallon is 5500 watts at 220v. You could, in theory, use a 5500w genny. Most would recommend going larger if you want the genny to last. Or you could use only 110v and have 1/4 of 5500 watts = 1375 w. I think you can replace the 5500 watts with 4500 or even 3500 watts.

So you decide what you want to do. I would decide on using the genny I have, however, producing electricity with gasoline is very expensive.

I'm going to guess someone will tell me that I can't use 110v on a 220v water heater, I've been doing it for over 20 years.

George

Usually 5KW for just the heater but I can't recomend using a home or hobby portable generator contious at it max rated capacity.
6500W minimum.
Problem is using a generator to electrically heat water. Only 1/3 of the fuel you pour into the generator's tank actually heats water.

I can't imagin why you would want to use a generator to make hot water. Buy a LP water heater for an RV that requires no electricity. (no motor, no maintainance.) I heat all my water with solar collectors, requires enough electricity to power a .75A circ. pump and a bit for the controler.
Loren, the Acg.

You are right about heat losses. Got to thinking, I've seen two people make a boiler like heat exchanger and use the exhaust to heat water. One guy was a vet and the other had a business cleaning carpet.

It's possible the exhaust alone will generater more heat than the electricity from the generator.

How quickly do you want to heat it, and from what temp to what temp.

The rest is BTU calculations.

Just run the hot exhaust into the base/burner section of a small gas or oil water heater.

Years ago a 20 gallon water heater used in mobile homes had a horizontal tube where the dry heating element went. That's what our vet used.

I don't see why an old gas furnace wouldn't work.

The boil exhaust my carpet guy made is real sweet. He graduated from Rose Hulman.

You are right, a gas engine may be at best 25-30% so 70-75% of the gas is heat.

I guess I'd look on the water heater label, or
name tag, for the wattage rating!