Tankless oil boiler water hot, cold then hot again


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Old 11-17-10, 04:08 PM
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Tankless oil boiler water hot, cold then hot again

I just moved into a place that has an oil boiler that is also a tankless hot water heater. When I show the hot water last for about five minutes and then it gets cold. If I leave it running, it stays cold for three to five minutes and then suddenly gets really hot again. Any ideas what could be wrong?
 
  #2  
Old 11-17-10, 05:19 PM
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Yeah, you have a thankless coil instead of a real water heater. Tankless coils in heating boilers are only one step above heating water in a kettle on a wood-burning kitchen range.


I know that isn't what you want to read but it IS the truth. There are several possibilities as to why your particular coil is as bad as it seems and they range from a shower head that has too high a flow rate to your coil may be severely scaled internally. There have been LOTS of questions and answers to this very common problem posted over the years in the Boilers sub-forum.
 
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Old 11-18-10, 04:28 AM
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I understand why I could run out of hot water, but I do not understand why it would get hot again so suddenly after being cold for a while.
 
  #4  
Old 11-18-10, 05:48 PM
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The coil only holds about five gallons (more or less) so it takes very little time to heat that small quantity of water. There are a few things that might help your situation but the real cure is a real water heater.
 
 

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