Multiple Pressure Reliefs
Looking for some advice on this system. It has been designed with pressure relief valves @ the boilers and the expansion tanks. I’m doubting if the ones @ the expansion tanks are required.
The PRVs on the boiler are integral and match the input rating of the boiler.
Comments
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where do they show a second PRV
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Shows one on each boiler, and one on each expansion tank (bottom right corner).
It’s the symbol next to where it says ‘to floor drain’.
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Might be some commercial code thing about pressure vessels.
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The ones on the boilers are all you need
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Are you piping this now? You might be able to get a letter from the engineer saying they're not needed. That would satisfy our inspectors around here, but I dunno about yours.
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Yes in the process of piping.
I am going to add the additional PRV’s @ the expansion tanks. It can take weeks here to get an answer from an engineer. I can always remove afterwards.
I just wanted to check and see if I was right about them not being needed/overkill.
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I don't think they would hurt anything, so I probably wouldn't bother taking them out once they're installed.
Sometimes, adding "delay of project" to the subject line will get them hopping—but sometimes there's nothing you can do to get them to move faster. In this case, since you've presumably already included the extra valves in your cost, I suppose they have no interest in answering speedily.
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On each boiler YES!
If the expansion tanks can be isolated, then the LAHJ MAY require them!
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Noted.
Yes technically the Exp tanks can be isolated. Although we always put lockshield valves on expansion tanks, and advise the building owner to lock them open.
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Then there required!
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You beat me to it. If there is a possibility that the PRVs at the boilers may be isolated from the rest of the system (not just the expansion tanks but the system as a whole) then I, at least, would have required them.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
In NYC, some boiler inspectors require an additional relief valve, same rating as boiler IF expansion tank has an isolation valve to the system. Over a fixed BTU...Mad Dog
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So if there's a manual shut off valve to the expansion tank, a boiler rated pressure relief valve is sometimes required at the expansion tank? That's what the OP's drawing is showing. Looks like actual taps in the expansion tanks. I've never seen such an animal, but I work on small stuff.
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I'm wondering where this job is located??? Since the diagram is redacted, it must be a TOP SECRET location, like the NSA, CIA or Secret Service building
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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if the boiler with PRVs attached is isolated from the system where expansion come from to require a system relief valve?
I suppose a failed fill valve could increase pressure
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0
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