Defective Thermostat or Dip tube issues

Old 11-02-17, 03:05 PM
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Angry Defective Thermostat or Dip tube issues

Hi everyone,

I have a 9 year old Rheem Fury gas heater. Lately, the water has turned lukewarm when we use it and it is getting progressively colder.

I replaced the drain valve with a 3/4 ball valve and flushed the tank a few times. Some sediment came out but not enough to explain the loss of water temperature. The problem still exists after the flushing.

So at this point, I believe it can either be a faulty thermostat or a broken dip tube.

Any ideas how I can troubleshoot either and eliminate or confirm the possible cause? Note: I am trying not to have to actually take out the dip tube.

Old 11-02-17, 06:39 PM
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Turn the thermostat knob up slightly, just enough to cause the main burner to ignite. Wait until the main burner goes off without using any hot water. Now draw off hot water into a bucket in the bath tub or laundry sink if you have one. If you run out of hot water soon then it is a dip tube failure.

Now it could be that the thermostat has been inadvertently "bumped" or moved and simply needs to be reset. Or it could be that after being set on a particular point for nine years the mechanicals have gotten sluggish in their action and merely moving it slightly will cause it to function well for a time.

Understand also that your heater is entering into the twilight zone where it could fail. Average life of a gas-fired water heater is between eight and ten years. With maintenance and good water they may go longer. At nine years of age it does not make economic sense to spend money on a new thermostat. Even a dip tube, if replaced by a plumber, is probably money down the drain.
Old 11-06-17, 04:04 PM
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Try this: Slowly turn the temperature knob up a few notches and then slowly turn it back down to where it was. If the heater kicks on and keeps running for more than 20 minutes and now you can get in a reasonably long hot shower that means that the thermostat has a problem.

Also try turning the control knob (a smaller knob) to "pilot" and then slowly turn the temperature knob all the way up, then all the way down, then back to where it was. Turn the control knob back to "run" and do the first paragraph above.

You might get good hot water for a few months by repeating the first paragraph every morning. But as was mentioned before, you are on borrowed time and it is now time to consider (and budget for) a new water heater.
Old 11-09-17, 08:48 PM
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There was a dip tube fiasco in the mid 90's and I haven't heard of anything new on that front. It's not that difficult to pull the dip tube out for a look-see. I'd bet on a gas valve problem, or a single handle faucet crossing over.

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