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Boiler circulation pump

If you have any air in the line the water will not circulate, I would think you need to purge the line of all air.


  • Alan_19
    Alan_19 Member Posts: 3
    Circulation pump doesn't come on

    i have an older Burnham Boiler Holiday with a circulation pump that is controlled by an aquastat surface mounted on the discharge line. Occasionally the burners would heat the water to as much as 200 degrees but the pump would not kick on. I thought it was either a bad aquastat or a flat spot in the motor. Unable to test it immediately when it happens I decided to just change the aquastat. It worked beautiful since fall but it is now doing it again. So it must be the motor right? That was theplan for the day, but I noticed today when the burner came on that the return line got hot quickly, but the discharge line(where the aquastat is mounted) was still cool with the boiler water at 180 degrees already. How can that be?
  • zeke
    zeke Member Posts: 223

    OOPs, please disregard.
  • zeke
    zeke Member Posts: 223

    Doesn't look like the motor, since it has the same symptom as before you replaced the aquastat. It does look like the discharge pipe is not immersed in the boiler water.

    Perhaps insufficient water level in boiler?
  • Alan_19
    Alan_19 Member Posts: 3

    If there wasn't enough water in the boiler would I not here air in the lines when it circulates?
  • Mike T.
    Mike T. Member Posts: 4

    Can YOU TAKE A QUICK PICTURE OF THE SET UP YOU HAVE AND POST IT? If I am reading you correctly, you are using a strap on temp control? SHould be strapped to the line off the top of the boiler. This control was probably added when the the origional Aquistat failed....correct?

    Mike T.
  • Alan_19
    Alan_19 Member Posts: 3

    First I want to thank everyone for taking the time to respond.

    I will try to explain again my problem if that doesn't work I may attempt a picture.

    The aquastat just runs the motor and is surface mounted to the discharge (top pipe) of the furnace. Most of the time everything works great. Once in a while the aquastat oesn't close to start the circulation pump. It is not the aquastat. It is the lack of heat in the pipe the aquastat is mounted to. When it works correctly the burner fires heats the boiler water which transfer enough heat up the pipe to trip the aquastat. When it doesn't work correctly the burner fires heats the water to as much as 200 degree but the heat for some reason doesn't rise up the pipe to tripthe aquastat. The return line will be hot do to the heat rising up in it,but the discharge will not get hot.It acts like there is is an air void in the discharge line, but the pipes are whisper quiet when the pump finally runs and I don't get any air out of the bleeder.
  • g rad
    g rad Member Posts: 7

    do you have a flow switch on the return line?This tells the boiler that you have water flowing into it.Could have been installed incorrectly to the pump and not the boiler controls.Also,I believe the aquastat should be mounted to the return pipe.What is the temp set at on the aquastat? Does the aquastat have a red reset button on it?
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