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How do I tell if my boiler pressure reducing valve is bad? I can't seem to purge my loops
Jells
Member Posts: 576
I added a new zone to my boiler manifolds today, and when I tried to purge the air from the loops I can't get enough pressure from the reducer, flipping up the lever seems to have no effect on the flow. Is there a trick to fixing/clearing these, or do I just get a new one?
It's one of these, a Bell & Gosset FB-38
EDIT: found the data sheet on this and it mentions cleaning the strainer screen. I'm going to wait till after the wife takes her morning shower before I risk taking down the heating system if I have a problem! Noisy baseboard is better than that.
It's one of these, a Bell & Gosset FB-38
EDIT: found the data sheet on this and it mentions cleaning the strainer screen. I'm going to wait till after the wife takes her morning shower before I risk taking down the heating system if I have a problem! Noisy baseboard is better than that.
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Comments
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You can try cleaning the screen, but in my experience, when they get plugged up, they don't clean up well and usually leak. Yours does have a brass body instead of cast iron, so you might make it work. Most likely you will need to replace it.
Rick0 -
To which I would add that it is a very rare situation where a pressure reducing valve such as that will pass anywhere near enough flow to actually purge a loop of air. You need to really get that water moving.Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
I've never heard of another method except vents on the rads. It's always seemed to work for me. Do tell of another method? Hook up a hose from a direct bib to one of the drain bibs to get line pressure? Gotta be careful with that, I've had old systems leak from a bad pressure valve that was not reducing!Jamie Hall said:To which I would add that it is a very rare situation where a pressure reducing valve such as that will pass anywhere near enough flow to actually purge a loop of air. You need to really get that water moving.
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Indeed. Hook up a hose directly and let her rip. Just don't close the valve on the other end, and you'll not build much pressure in the pipes. If you are concerned about old pipes, just close the valve on the hose down enough to keep the flow down to say 3 or 4 gpm.Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Is the manual valve before the PRV open?
I wouldn't open it to clean without a new gasket.0 -
So I replaced the PRV, and tried Jamie's idea. I think it destroyed the valve! When the boiler was running this valve preset to 13psi shot the pressure up over 60, which is how I discovered my safety relief valve was bad. This just keeps getting better. I had to unscrew the setting screw on the PRV all the way to get it under 20psi, and it still seems erratic.
Or is it possible I overheated it when sweating the joint 8" away? I had to heat it pretty long because there was some water in there. If I have to redo this I'm adding a union, don't know why these valves don't come with them to begin with like tempering valves.0 -
Taco and Watts and others offer them with unions.0
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I don't see how it could have destroyed the valve -- if you did it right. There should have been no flow through the pressure reducing valve at all, and the pressure in the whole system should never have gone over perhaps 10 pounds.Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
when pungent purging, if possible isolate all the zones or loops except for the one you are purging
In fast fill you should get 5 gpm or moreBob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0
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