Should one turn off the hot water heater if not using the house for a week? or just leave it on?

I would leave the heater on but turn off the main water supply. I had a small leak in a copper pipe the was undetectible. We left for a week and when we got home the pipe had split and we had water everywhere. If you turn off the main water you will never have to worry about coming home to a flood. Caution, though, when you turn on the water when you get home make sure you have opened all of the faucets and then turn on the main very slowly. I learned if you turn it on too fast and the faucets are not open the pressure can knock sediment in the pipes off and that can lead to clogged faucet heads.

The water heater will be fine being left on. The water won’t be used so the tank will be full and the heater will seldom kick on.

leave the water heater on. if you turn it off, the water would get cold, thus requiring more energy to heat it back up. if you are looking to save energy, you can decrease the temperature of the heater. our new one has a “vacation” setting.

I lower my temp down to 90 if I leave the house for more than 3 days.

Main cutoff is a good idea too.

When I was reading Sueanne’s, I could have sworn I wrote it. We went through exactly the same thing. It was a pinpoint leak in the ice-maker tubing and that tiny leak flooded more than 1/2 the bottom floor of the house and a good part of the backyard. We never leave the house for any extended period of time without shutting off the water to all of the house.

I turn it to pilot light.

Set the thing to “Vacation”....
Remember to re-set it when you return from your trip….

With the formulation of cold water soaps for cleaning clothes, why is it necessary to wash laundry in hot water? Does hot water have better cleaning power than cold water?

With the formulation of cold water soap, why is it necessary to use hot water to wash laundry? Does cold water have better cleaning power than hot water?

@1941, i don’t think you understand how Fluther works…you can go ahead and create a new question for your question instead of hijacking another question. Just go back to the main page and enter your question there. this will make sure that everyone can see your question. if you leave it here, the only people that will probably see it are the people who responded to this thread a month ago.

There is no “shortest time” from an energy-saving POV, only from a nuisance or convenience POV. The physics is straight-forward:

You’re paying for energy to heat all the water that you use, plus the heat you waste up the chimney if you’re burning fuel. Plus you’re paying for all the “standby” or “tank loss” energy that moves through the tank wall into the surrounding space, plus the heat you waste up the chimney if you’re burning fuel. If you’re also heating the house (basement), you’ll get some savings from the tank loss, though usually not 100%. If you’re cooling the house (basement), you’ll get some additional costs from running the AC to pump the extra heat out of the house.

Since you’re not using any hot water while you’re away, it’s obviously all about “standby” or “tank loss” energy. The rate of energy loss through the tank wall is a direct function of the “delta T”, i.e., the difference in the temperatures of the hot water inside and the air outside. Every day, hour minute, second. . . you let the water temperature drop closer to the air temperature, it loses less energy and you save energy and money. Sure, it takes energy to reheat the water, but the total energy loss is dropped by the temporary turn-down.

The only minor wild-card here is that the energy efficiency of most water heaters isn’t constant, but is affected by changes in tank temperature, length of “burn”, etc.. But I’m pretty sure the net direction of those changes is to add a bit to the savings, so it’s even more worthwhile to turn it off (or down) whenever it’s convenient.

Norm in Toronto