Turning off electric hot water heater when not home?

[jakemacd]

When I was living alone, I would turn the temperature of the water down in my water heater so that when I took my morning shower, I just had to turn on the hot water faucet. I didn't add any cold water. I could take nice "hot" leisurely shower (up to ten minutes) and the water would stay very comfortable. Also, when washing my hands or shaving, just the hot water faucet would be used. The dishesfrom my electric dish washer came out nice and clean.
The rate of heat transfer increases with the temperature differential. Even is your tank is insulated well, you are going to lose more heat (energy) faster from a tank sitting at 150F in a cold basement 45F then if your tank is set at 115 or 120. I realize that if there are a lot of people taking a series of showers in your home, this method would not be as practical. Also, mine was a natural gas fired heater which I understand recovers faster than electric. Hey, live alone or just the two of you? Give it a try.

[Tango Charlie]

Originally Posted by fshagan

It takes a certain amount of energy to raise the water a degree ... 2.42 watts per gallon. If you have to raise it 10 degrees, it doesn't matter if the heater comes on ten times to raise it one degree, or if it comes on once to raise it ten degrees. You use the same energy to recover the 10 degrees of heat you lost.

Here's another aspect to consider; with a timer installed and set to fire up the WH during lower electric rates, there's an advantage for ya. Instead of 6,7,or 8 of those one degree cycles at daytime rates, you're getting all 10 during the reduced rate.

[dremd]

I have a switch in my pool house; works great. It is only occupied 2~3 days a month.
I just upgraded it from a 2.5 gallon with all of the insulation gone to a new 6 Gallon should work even better (but with increased recoverytime). (both units 1650 watts)

[BrianAbington]

Originally Posted by jakemacd

When I was living alone, I would turn the temperature of the water down in my water heater so that when I took my morning shower, I just had to turn on the hot water faucet. I didn't add any cold water. I could take nice "hot" leisurely shower (up to ten minutes) and the water would stay very comfortable. Also, when washing my hands or shaving, just the hot water faucet would be used. The dishesfrom my electric dish washer came out nice and clean.
The rate of heat transfer increases with the temperature differential. Even is your tank is insulated well, you are going to lose more heat (energy) faster from a tank sitting at 150F in a cold basement 45F then if your tank is set at 115 or 120. I realize that if there are a lot of people taking a series of showers in your home, this method would not be as practical. Also, mine was a natural gas fired heater which I understand recovers faster than electric. Hey, live alone or just the two of you? Give it a try.

what did you have the tempset at? 120? 115? or lower?

[Cd]

Hey guys, my dad recently tried flipping the breaker for the "hot" water heater, and it works like a charm !

I live in an apartment and the water heater is gas.

Is there anything that I can do to make the water heater operate only when I need it ?
Since it is gas, I cant just flip a breaker.

( Actually, the trick would be getting to the thing, since my apartments have it behind a locked door on my porch. )

Thanks !

[newhavenpatriot]

What if you turned off your hot water heater and installed very small hot water heaters for each bathroom and the kitchen of your house, and then just heated up the water when you needed it? Water in a tea kettle doesn't take that long to boil, so I figure you could get water up to a decently hot temperature in a minute or so, depending on how much hot water you needed. I hear the Chinese do this, rather than wasting tons of energy with one huge hot water heater that's always on.

[Cd]

Originally Posted by newhavenpatriot

What if you turned off your hot water heater and installed very small hot water heaters for each bathroom and the kitchen of your house, and then just heated up the water when you needed it? Water in a tea kettle doesn't take that long to boil, so I figure you could get water up to a decently hot temperature in a minute or so, depending on how much hot water you needed. I hear the Chinese do this, rather than wasting tons of energy with one huge hot water heater that's always on.

That's a great idea - really !
, but it reminds me of this image. The guy that rigged this up didn't put much effort into it !

I censored the image so as not to offend anyone.

[newhavenpatriot]

Haha! Bonus points for putting the coffee machine(?) where it can fall in and electrocute someone if the water's on!

[sandcruiser]

It depends a lot on the ambient temp of the house or closet where the heater is located.

The original poster asked if flipping off the breaker in the morning, then resetting it in the evening will save power.... the answer is absolutely YES.

The reason is simply that heat exchange is not linear to the difference of heat. If the water heater is 60 degrees warmer than the house (60* house, 110* water heater), it is losing heat FASTER than if it is only 20 or 30 degrees warmer than the house. So the heater will likely cycle during the day to keep the hot water hot enough.

If turned off, the heater will radiate heat and get cooler... but it cools more slowly as it gets closer to ambient temps. When you turn it back on, nearly 100% of the heat that is produced by the element goes into the water.

The question becomes: is the heat lost during the day enough to bother flipping the breaker? Since flipping the breaker is essentially zero-cost... it makes sense to do it. Unless the extra breaker cycles shorten the life of the breaker. That could negate savings.

If you wake up more than 1/2 hour before your shower(s), the best thing to do might be turn off the heater all day and all night, just turning it on 30-60 minutes before you shower, then turning it right off after the showers.


Or just get an instant-on hot water heater (tankless) and be done.

Originally Posted by fshagan

Electric water heaters are insulated pretty well, so you probably won't save much by turning it off. 100% of the energy goes into the water as heat (or very nearly so), so the only losses you can save are "standby losses" from heat radiating out of the jacket. Because electric water heaters don't have a flue that tends to cool the water, they usually retain the heat very well.

If you turn it off after it is hot, leave it off for 8 hours and turn it back on, does the element have to come on to heat the water again? If it does, spend your money on insulating the tank, the pipes coming out of the tank, installing a "thermal trap" in the outlet pipe, etc. If the water in the tank is still above room temperature then you haven't lost all of the heat and you won't save much energy by waiting until you come home to turn the elements back on. The intermittent use of the elements during the day will come very, very close to the longer run you need when you turn the elements back on.

[Christ]

Why not just get a $20 timer from Home Depot? My Father's been doing this for years, he runs the water heater approximately 1 hour before he gets up for work, and still has hot water when he comes home. Not HOT HOT, but at least enough to wash hands, couple dishes, etc.