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Air lock

URISteve
URISteve Member Posts: 2
in THE MAIN WALL
I currently have a contractor with a strange little problem that appears to be an air lock on the inlet side of the pump on a hot water system.  There are 2 air eliminators on this system, both a good 6 to 7 feet away from the pump and around a few elbows.  The pump is on the return side of the boiler and has isolation/check flange mounting.  And there doesn't appear to be any leaks in the closed loop primary/secondary system.

This only occurs about once a week and keeps the system from running.  I told the contractor I would go to the job and look at it with him this morning while it is currently locked up.

I'm at somewhat of a loss.  Any Ideas?

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 24,110
    No ideas, but a question...

    Where is the expansion tank in relation to the inlet to the pump?  It should be as close as feasible to the INLET of the pump...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • pipeking
    pipeking Member Posts: 252
    NEED SOME PICS

      to see whats going on. is the pump mounted in the mfr. recomended configuraton. how do we know the pump is air bound
  • URISteve
    URISteve Member Posts: 2
    Expansion tank

    Expansion tank is just around an elbow about 6 ft in front of the pump, mounted to the bottom of the air eliminator.  System has been up and running for close to 10 years without any problems till now.
  • RJ_4
    RJ_4 Member Posts: 484
    Air

    Are there automatic air vents on top of air seperators, if so they could be drawing air into system especially if your n.p.s.p ( net possitive suction press, ) at your pump goes below 0 psig.  I recommend all air vents on hydronic systems be valved off after initial fill and bleed.   pictures would be good

    There was an error rendering this rich post.

  • Jamie Hall
    Jamie Hall Member Posts: 24,110
    OK -- next question

    as RJ notes, if the net positive suction pressure at your pump inlet -- or at any of the air eliminators -- drops below 0 psig, you are surely going to have a problem.  So the question is: what is the pressure at the expansion tank and the pump inlet when the pump is running?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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