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Hot water turns lukewarm (cold) after 5 minutes (possibly broken dip tube)?

Hot water turns lukewarm (cold) after 5 minutes (possibly broken dip tube)?


  #1  
Old 01-31-13, 07:33 AM
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Hot water turns lukewarm (cold) after 5 minutes (possibly broken dip tube)?

I want to test my dip tube which I suspect is broken. I have hot water coming out in the house but it turns cold after some time

If I turn on the hot water, cold water from the inlet should rush into the tank. Ideally, if the dip tube is in tact, cold water should flow down to the bottom of the water heater. The cold water should be in contact with the thermostat causing the burner to turn on and heat the cold water.

How long does it take for the burner to turn on? How do I diagnose this issue?
 
  #2  
Old 01-31-13, 07:38 AM
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Welcome to the forums.

From your description, this is a gas WH, right?
 
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Old 01-31-13, 08:23 AM
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Yes, this is a gas water heater.

I have two of these, one for each floor.

I turned on the hot water for the one of the floors and it took 1 minute for the burner to turn on.
I then turned on the hot water for the other floor and it took 3-4 minutes for the burner to turn on. I suspect the dip tube is broken so the cold water is immediately being mixed with the hot water at the top of the tank instead of being shuttled down to the bottom.
 
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Old 01-31-13, 09:16 AM
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How long it takes to turn on depends on how much water you take out. It's all controlled by the temperature the thermostat sees. If the dip tube is broken it may take longer since the all the water movement in/out is at the top.

As for diagnosing I check everything else to rule out more easily diagnosed problems. Luckily on a gas water heater with one thermostat it's a pretty short list to check. Then turn off the water, disconnect the inlet plumbing and remove the dip tube. If it is broken pat yourself on the back. If not, curse and throw a wrench for the time you've wasted. That's what I do.

From what you've said I also suspect the dip tube.
 
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Old 01-31-13, 09:20 AM
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Thanks, it could it also be a busted thermostat. The thermostat may not be calibrated correctly or something?
 
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Old 01-31-13, 09:21 AM
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I'm with the dip tube as well - has this been an electric WH, I would have been thinking bad lower element.
 
  #7  
Old 01-31-13, 02:09 PM
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Do a bucket test.... How many gallon HWH is it?

Fill a 5 gallon bucket at a tub and count how many buckets you get before the water cools. A 40 gallon you should get around 32 gallon out. About 6 buckets.
 
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Old 02-01-13, 05:50 AM
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I do not think it is a bad thermostat since the poster has said the burner does come on, but takes 3-4 times longer to do so than his other water heater when he tests. And, since there is only one thermostat on a gas water heater it's more an all or nothing situation. Not one that would only give you a small amount of hot water.
 
 

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