Pressure surging in boiler


  #1  
Old 10-08-05, 05:53 PM
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Pressure surging in boiler

Hi All,
I have a 1973-vintage American Standard gas-fired hot water boiler serving a one-zone baseboard radiator system throughout the house. The pressure surges back and forth between 15 and 20 pounds while the burner is firing, especially if the boiler is starting out cold. This "pulsing" occurs about four times per second. The system water is clean, and there is an adequate amount of water inside the expansion tank-- maybe 1/4 full.
Any ideas on what is causing this? The boiler runs fine other than this problem, maintaining 15 pounds after the boiler is hot.
FWIW- the boiler has cast-iron sections.
Thanks!
 
  #2  
Old 10-09-05, 10:34 AM
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Boiler surging

This is not uncommon in gas or oil fired "dry base" boilers & is caused by water actually boiling in small spots. Other than chemically cleaning the waterways of the boiler, there isn't much you can do about it. Sometimes the cleaning works & sometimes it does not.
 
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Old 10-09-05, 04:20 PM
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Thanks for the reply!
I had a feeling that that might be the cause. Since the pressure stays well below the limit, I won't worry about it.
 
 

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