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First floor zone calls for heat and boiler keeps turning on off

jogrady Member Posts: 5
I have a slant fin boiler hot water baseboard the first floor zone calls for heat and the boiler short cycles .
I replaced the thermostat and also replaced the expansion tank which was filled with water. I also bled all three zones and air came out. I also have been having banging pipes. After the bleeding and installing new expansion tank banging stop for a day but then came back. Could the first floor zone valve e bad and be causing this problem.


  • DZoro
    DZoro Member Posts: 1,048
    Could be the zone valve stuck closed. Do all the Rads. in that zone come up to proper temperature?
  • HomerJSmith
    HomerJSmith Member Posts: 1,563
    You did open the boiler water feed valve, I hope. What does the temperature / pressure gauge say.
  • DZoro
    DZoro Member Posts: 1,048
    How many pumps? Power to them? Supply hot, return cold 5-6' away from the boiler?
  • John Mills_5
    John Mills_5 Member Posts: 935
    1 zone calling it is likely the boiler will short cycle. How fast is it cycling? Approximately what % of your radiation is this zone?