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problem replacing circ isolation valve that has check valve built in

Nom_Deplume Member Posts: 68
edited May 21 in THE MAIN WALL
Hello...the relevant part of our hot water heat setup (arrows indicate water flow direction) is

boiler --> isolation valve ---> circ --->isolation valve with check valve -->to radiators upstairs

The check valve started chattering some months ago and I asked about it here. I want to replace the valve marked in bold above.

These are standard flange valves, sold in pairs by Bell&Gossett/Check-Trol and others. See e.g. this link. There is no built-in way to prop the check valve open.

So the problem is that the water to the right of the diagram, up to the radiators, has no way to drain out. I can drain the radiators themselves through the return path, but there's water upstream of the valve and so I cannot unsolder it!

Is there a trick to this? Many thanks,

PS I stuck my finger into the check valve for a sec (detached from the circ of course) and water spewed all over the wall, electrical wiring, etc. Because of the actual layout there is no good way to collect the water.


  • unclejohn
    unclejohn Member Posts: 1,726
    You could use your finger and a wet vac.
  • Big Ed_4
    Big Ed_4 Member Posts: 1,722
    You can hook up a pump to the return and unbolt the check flange and pump out the supply . I would recommend cutting one side of the pipe of what you are trying to unsolder .
    I have enough experience to know , that I dont know it all
  • mattmia2
    mattmia2 Member Posts: 3,168
    unclejohn said:

    You could use your finger and a wet vac.

    Or just a wet vac somewhere in the discharge side of the check valve. Or a long screwdriver or rod and a rag and bucket.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,172
    edited May 21
    I have places a bucket below the fitting I am removing, set up a pump to pump out the bucket, loosen the fitting until it starts to drip, Then carefully allow the fitting to drain into the bucket with the pump operating. depending on how much water is being held up by the check valve, this could take some time. Use your hand to act as a valve to throttle the flow into the bucket to match the pump capacity.

    Mr. Ed.

    P.S. Sounds like you are getting wet on this one!
    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
  • Nom_Deplume
    Nom_Deplume Member Posts: 68
    OK, thanks everyone for confirming that there is no simple trick. The tangle of pipes and electrical wiring in the area made things difficult. I drained it, but yes, I got very wet on this one.

    I considered putting a drain valve upstream, but finally didn't do it...this problem doesn't happen often. The valve with the chattering problem had been installed 16 years ago.
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