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capt2 01-16-2008 12:17 PM

Water Heater Timer
I put a timer on my elec hot water heater. It appears to be an 80 gal tank--AO Smith "Conservationist '90" (Also says Perma Foam on the tank)

I wanted to know how to select the best ON/OFF times. How long does it take to heat the water after an off period?
Also I noticed that the water was still hot 6 hours after it was shut off. One feedback I got is that it takes about 3 days for the tank to cool down.

Another feedback sugests that timers are waste of money--nearly useless.
What do you guys think?? Thanks in advance.

Bondo 01-16-2008 03:25 PM


I gotta believe that 80gal. probably will take 3 days sitting in an insulated tank, in a Warm surrounding, to cool down,.......

That tank probably Never comes "On" til you've had a faucet on for a few seconds,........

Unless of course you spend extended periods away for there......

bigMikeB 01-16-2008 04:56 PM

Timing on the heater would depend on your schedule. If no one is home during the day you could have it turn off until two hours before your return. You could also have it off overnight until a couple of hours before the first morning shower time. Yes the water will stay warm in the tank for a while.

Mike Swearingen 01-16-2008 05:28 PM

I put a timer on our water heater and set it come on one hour in the morning before we get up and for one hour in the evening. My wife was forever switching it ON, so I finally just bypassed it. Another wasted "great idea". LOL

Marlin 01-16-2008 06:04 PM

Timers are a waste of money. The water temperature probably falls six or seven degrees in the six hours you're at work. Even over a day when the water falls 30 degrees or so what difference does it make if you heat the water 30 degrees all at once by running the heater for twenty minutes or heating the water ten degrees at a time during three seven minute cycles, the heater runs the same.

If you want to get into basic physics then yes, you do have more heat loss when the temperature is higher. This is because the bigger the gap in temperature between the water and the surrounding air the faster the heat is transfered to the surrounding air. This occurs in the same way that a cup of coffee will get colder faster in the refrigerator then it would at room temperature. This difference is so negligible due to the insulation on the tank that you will never even recover the cost of the timer.

My advice is not to touch the water heater unless you are going to be gone for two days or more. In that case put it on vacation and you'll probably save yourself fifty cents a day.

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