Operating cost of idle electric water heater?

Unknown

For reference a 79 gall viessmann indirect loses 6800 btu/24hrs.

your average electric tank is probably not insulated as well, but this gives some indication.

I was looking at this the other day,in terms of the pros-and cons of instantaneous heaters and figured out that in a year (at current oil prices and 80% efficiency) standbyloss = around $100 per year . This doesn't include heat left behind in the boiler during non-heating months. I would imagine that with a high mass boiler this is a fairly significant number, maybe even more than what is lost directly thru the tank.

At this point with electricity @ 13kw/hr and oil pushing $4.75, electric resistance is looking very competitive especially compared to combustion equipment that is operating @ %80 efficiency.

I say leave the water in it and shut it off, keeping the water hot should have no impact on corrosion, the only danger is bacterial, make sure to get the tank up above 130 and allow it to sit at this temperature for awhile before putting it back in service.

Charles_10

Depends on cost per kwh, I know...

I just moved into a large house that has two electric water heaters. I don't need hot water on the other end of the house so I would like to shut down that heater.

Should I:
- leave it idling? If so, about how many kwh per month would that waste?

-turn it off? Would condensation/rust become a problem just like with a boiler that is shut off for the summers?

-turn it off and drain it?

Opinions welcome.

thanks
Charles