Turn the water heater off or leave it on?

[SecondMonkey]

I have a 40 gallon electric water heater in my shop. It mostly just gets used for washing hands, the rest of the time it just wastes electricity. It is, however, better insulated than I thought it was. I was turning off the water heater breaker when I leave the shop - I'll usually be gone 12-72 hours when I do.

Then I realized there is only about a 10-15 degree temperature drop after 24 hours in a ~40 degree shop with the heater off. Of course that's bigger if I'm gone for longer. I like to keep it at about 135 degrees.

Anyway, do you think I'm really saving anything turning off the breaker before I leave? Or am I just wasting more juice by letting it cool and heating it up again every time I get there?

 

[HTSS_TR]

If it is used to washing hands and nothing else, you can set it at around 110-115F and leave it on. The newer water heater are very well insulated, you don't need to turn it off unless you don't need it for several days/weeks.

 

[Herz]

I would just keep it at its lowest setting or looking into a smaller one

 

[XS650]

For relatively small temperature swings like that, there is essentially no savings. The only savings is because your tank average tank temperature was lower by (temperature swing)/2 so you lost less heat through the insulation.

 

[daves66nova]

use gloves so that you don't have to wash your hands as much.

 

[SecondMonkey]

Well, I like to keep the temp high because I also have a hot water hose spigot hooked up for cleaning engines and such. Also a big laundry sink for cleaning greasy parts. And a shower. Although those are very intermittent uses. An on demand heater would be great but not worth the cost...

The water heater is not very new though, I couldn't find a date but I know power was installed in my building in 1997. I was very surprised how little the temp dropped overnight. I was going to add more insulation but I doubt that would help much...

 

[djb]

If the water temperature isn't dropping much, you are saving very little.

Standard panel circuit breakers aren't good switches. There are SWD (switch duty) circuit breakers rated for that use -- reasonable life with a daily on-off cycle. If the breaker isn't rated for that use, it could fail in a few years. If you have to pay an electrician replace the breaker, it would easily overwhelm your slight savings.

 

[rjundi]

Even for vacation, you turn it down in temp never off.

Leave it be.

To improve efficiency buy an inline unit or smaller tank.

 

[mechtech2]

We turned ours off at night most of the time [shop].
Worked well in summer, with an obvious slowdown in winter.
Try it and see.

 

[tom slick]

Buy a tiny tanked or point of use unit for the sink and only turn on the big unit when you need lots of hot water. The hard part is recouping the $200 the unit costs.

 

[Smokescreen]

Why not put it on a timer of some kind?

 

[GMBoy]

I bet you're only talking about $10-15 bucks a month. Just set it at the lowest temp that'll do what you need and forget it.

 

[stranger706]

I noticed the same thing. I used to turn the water heater off for our house when we would leave town for a weekend. I thought I was saving some money. One Sunday night when we got home I forgot to turn it back on and went to run some hot water. The water heater was off all weekend and the water coming from it was still pretty warm. It really surprised me. Made me realize how well insulated the tank was and that when your not using hot water, the heater probably only kicks on like once or twice a day to keep the water hot.

 

[SecondMonkey]

Originally Posted By: tom slick
The hard part is recouping the $200 the unit costs.

Exactly. I keep looking at that sticker on the side that says it uses an estimated $417/year in energy costs, at 1994 prices. But that's probably for normal family use...

 

[Cogito]

Do you think that continually putting it through cycles where it heats up and cools off might put thermal stress on the glass liner, causing it to fail prematurely?

 

[SecondMonkey]

Originally Posted By: Cogito
Do you think that continually putting it through cycles where it heats up and cools off might put thermal stress on the glass liner, causing it to fail prematurely?

Who cares, it's the landlord's.

Would be a good excuse to put in a demand heater, and this one is getting kind of old...

BTW, how many years do you guys normally see from an electric WH? I remember replacing one about a decade ago that couldn't have been more than 5 years old...

 

[mechtech2]

The compressor got turned off, too.
If a line blew, it would run all night.

 

[SecondMonkey]

Originally Posted By: mechtech2
The compressor got turned off, too.
If a line blew, it would run all night.

Yeah, I always make sure mine is unplugged. In my old shop my idiot neighbor always forgot to turn his huge compressor off, and never fixed the leak it had. It would run all night at least once a week...

 

[pavelow]

Just leave it on.