Turning off water heater

[aafadca]

They're are times when I 'm out of town for 2-3 weeks at a time. I know my older electric water heater uses alot of electricity. I usually turn the water off when I leave but I was wondering if it would damage anything if I turned off the heater for 2-3 weeks while I'm gone. Just wondering

 

[cvorkian]

Shutting the water heater off at the breaker is only damaging if you consider that a breaker is not designed to be used as a switch.

If you do this often, one MAY think of adding a seperate switch at the water heater.

Occassional use of the breaker in that manner isn't too much to worry about... your energy use and or savings is up for debate though....

 

[CoryZ]

My in laws do this at their vacation home no problems and haven't worn out the breakers. You may want to turn off your main water valve as well.

 

[Bear]

I've been shutting mine off for over 20yrs. even for only a 3 day long weekend. I also use a timer so that it only heats the water for when we need it.

 

[Steevo]

I have a new, efficient 30 gallon electric WH in my shop, and I just set the temp down to where it is just barely too hot to hold your hand under running hot water. I leave it running 24/7/365 to avoid freezing, and it adds about $6 to my electric bill every month.

 

[Outlander]

What about the quality of the water after being heated and cooled and left in the tank?

 

[NitroPress]

For weeks, yes, switching it off is probably worthwhile. For a weekend? A few hours a day? You really need to do the math. HEATING the water costs a bit, but maintaining that temp with the insulation and short heating bursts probably costs so little that turning it off and forcing all the reheat at one time saves next to nothing.

The real savings would come from putting in a more efficiently-fueled water heater. I don't think anything can beat gas in most locales.

There are ways to save money on electricity use, but micro-managing already efficient appliances isn't going to save much.

 

[Frank The Plumber]

Your only concern about the old water being left in a vessel like that will of course be microbial, you could grow some funky bugs in there and the other concern will be hydrogenation of the water resulting in freed hydrogen gas.

When you first turn the water back on and run it at the taps you may notice some air trapped and spurting out of them. There is always a possibility that this could be hydrogen gas which is flammable.

Just keep that in mind and don't have a cigarette in your mouth when you get home and turn on the water. Most times when I come home after a few days I purge the hot taps just to keep it safe.

If the water stinks flush the hot side for a while prior to restarting the heater to put some fresh water in there.

 

[tfi racing]

I would like to see some real measured data.Does it take more/less energy to maintain forty gallons of water at a given temp(140ish) for two weeks,than to bring it up from room temp(60ish) to 140 as fast as the heater can do it?

 

[NitroPress]

I would like to see some real measured data.Does it take more/less energy to maintain forty gallons of water at a given temp(140ish) for two weeks,than to bring it up from room temp(60ish) to 140 as fast as the heater can do it?

From past experiments (mine and others, some as formal as Consumer Reports) the break-even point for a reasonably modern, high-efficiency electric water heater is about 72 hours. Up to that point, you will spend less keeping an unused tank of water warm than re-heating it. Past that point, it's better to shut it off and let it reheat. Between 72 hours and a week is iffy on savings, any longer and it's a no-brainer.

 

[Jackfre]

A btu is the amountof water needed to raise one lb of water 1deg F. A gallon of water weighs 8.33 lbs. You would have to figure out the heat loss on your tank over time. You will loose less per hr over time because the delta T is less compared to ambient. There are 3414 btu in a kwh. Have a ball!

Frank is correct on the bug deal. I have a friend who got a whopping case of Legionellas out of his vacation homes water heater, which he would turn off all the time and ran at a low temp. Screwed him up! Be careful with low temps.

 

[chickenhauler]

Electric heaters are a lot more efficient than gas when not being used since there isn't a cold flue sucking the heat out. I've had them shut off for a week before and still had hot water when I drained them. If there's no water being used, I can't see how you would save much turning it off for a long weekend.

 

[anodyne33]

If I'm not home for periods of a week at a time and turn my (water) main off is there any problem with leaving the electric tank on?

 

[Frank The Plumber]

Yeah, On at temp or off and flush the heck out of it or you risk Legionaires disease. If you figure out the risks and flush the unit I would just leave it at temp unless you go away for more than a week.

 

[rlitman]

Electric heaters are a lot more efficient than gas when not being used since there isn't a cold flue sucking the heat out. I've had them shut off for a week before and still had hot water when I drained them. If there's no water being used, I can't see how you would save much turning it off for a long weekend.

Exactly!
On that note, with a gas heater's flue losing so much heat up the chimney, there isn't much point to adding lots of insulation. Not true for an electric.
You can insulate the heck out of it, and reduce your standby losses even more.

If you haven't done this already, here are a few suggestions:
1) add heat traps to the pipes (or at least use dielectric unions, as the plastic transmits less heat than the direct pipe connection).
2) add pipe insulation to the first few feet of pipe (cold AND hot) attached to the heater, and seal it up well
3) add an insulation blanket (or do something yourself)

Insulate enough, and it won't really use a significant amount of heat sitting for a few weeks anyway, and you won't have to worry about breeding listeria (or iron-fixing bacteria that will rot your tank/pipes).