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Old 01-23-2010, 12:04 PM   #1
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Gas water heater poor temperature control

(first post)..

We have an AOSmith gas hot water heater, about 5 years old and it is exhibiting a problem of really poor temperature control. (temperature at the tap varies anywhere from tepid to really hot (probably from 105 to 140+ degrees). We have the temp control knob at the 'B' setting just to make sure we have hot water at all. At any point during the day, you never know what temperature the water will be...

The house has a hot water recirculation system that turns off at 11 pm and back on at 4 am.

I'm guessing the gas control valve... any other thoughts?


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Old 01-23-2010, 04:56 PM   #2
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I would not have expected this problem for a heater only 5 years old but sometimes the burner does not kick on after the tankful of water has sat unused for several hours and cooled down somewhat. Then when someone uses the not so hot water and colder water enters the bottom of the tank, the burner finally kicks on.

If you manually turn the knob and the heater kics on after just one or two notches, then the water inside was not so hot. Turn the knob back to where it was whether or not the burner came on.


The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.
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Old 01-23-2010, 06:40 PM   #3
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poor temp control

Alanj, I wouldn't expect that... the Recirculation pump turns on at 4am and then continuously circulates the hot water through the house and back into the tank when it starts up, I would have expected that to cool the water down enough to start the flame.. Given that in the worst cases, this seems to drop the water temp to about 100 degrees, I' surprised that it hasn't started up and warmed up by the time we get up at 6 am.. two hours seems a long time to recover..
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Old 01-24-2010, 08:29 AM   #4
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I wonder if your check valve may be "leaking" and allowing cold and hot to mix. Or possibly if one was installed at all?
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