PRESSURE RELIEF

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91LMS

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Oct 20, 2011
217
MAINE
the biomass 60 does not appear to have a smaller bung/provisions to put a pressure relief valve on the boiler itself so I assuming in need to add it in the supply piping. is it acceptable to place it in a t and does its orientation matter? (i.e. horizontal, vertical, etc.)
 
I put mine in a T, on the top of the boiler. It wasn't exactly a smaller bung so think I reduced it. The T is 'sideways', with the relief sitting vertical on top, and the other T opening going horizontal to my NO dump zone valve then beyond to that zone.

You don't have any bung up there at all?

How close are you - getting excited? ==c
 
I am getting super excited. got the broken stuff fixed, now to plumb to my existing plumbing and wire up the control, pump and fans. its 2" reduced to 1 1/4 on the supply outlet and the only other bung for piping is the 2" return on the back. my old boiler had a dedicated 1" bung for a relief valve. I was hoping to t my supply pipe right off the boiler supply which would leave me a spot for the relief valve leaving the mounted sideways. wasn't sure if that would be an issue.
 
I am getting super excited. got the broken stuff fixed, now to plumb to my existing plumbing and wire up the control, pump and fans. its 2" reduced to 1 1/4 on the supply outlet and the only other bung for piping is the 2" return on the back. my old boiler had a dedicated 1" bung for a relief valve. I was hoping to t my supply pipe right off the boiler supply which would leave me a spot for the relief valve leaving the mounted sideways. wasn't sure if that would be an issue.


Here is the I&O from B&G.

I'd add, never have an isolation valve before the relief, and always add a discharge line to the floor, or into a bucket if it has glycol.
 

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so I will have to t into my supply line with a short nipple with another t or 90 to get it in the upright position. glad I asked before I got this all threaded together.
 
Generally relief valves are allowed on boiler exterior piping as long as there are no isolation valves between the boiler and the valve. If the valve leaks you need to drain the boiler.
 
If the valve leaks you need to drain the boiler.

Which makes it tempting to isolate it with a full-port ball valve and remove the handle in the OPEN position. Only clost it for relief change but you don't need to drain/ really fast swap/ mess for a simple relief valve replacement.

Remember this is on YOUR boiler not a customers. Leave a note on the valve if you want DO NOT CLOSE!

Just my .02

TS
 
If there are shut off valves on the other piping, there shouldn't be much draining to do to swap a relief valve out if it is at or around the top of the boiler.

EDIT: Kind of finding it hard to believe there are only two bungs on the boiler, and only one at the top. I think any boiler I have seen has provisions in bungs for a dedicated port for relief.
 
My boiler was that way as well only one temp well (1/2"at that) and simply two 2" male NPT for supply and return. I used a 2" T on the supply with a 2" to 1.25" bushing for my supply and a 2" to 3/4" bushing for the PRV.

Oh and a 1/2" boiler drain below the return port, I considered T'ing into that for a 3/4 PRV but that is not really that right way to do it.

TS
 
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i have all the sheetmetal off maple and there is no provision for a prv.... temp and pressure sensor wells for the gauge in the heat exchanger and then just 2 2" for supply and return. i thought the same thing and did a last minute panic when i was making my material list.
 
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i have all the sheetmetal off maple and there is no provision for a prv.... temp and pressure sensor wells for the gauge in the heat exchanger and then just 2 2" for supply and return. i thought the same thing and did a last minute panic when i was making my material list.


Euro boilers often use a fitting like this to group all the components into one boiler port.

Just make a tee or cross with off the shelf fittings. Hopefully that port is 3/4", you don't want to reduce the connection to the relief valve.
 

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I put a four way on the top of the outlet. one hole for supply, one hole for pressure relief and a temp / pressure gauge in the other hole even tho there is one on the boiler.
 
This may have already been stated above but your local codes will likely have something to say about PRV discharge. I believe here in MI the requirement is that any PRV must be plumbed to be within 6" of the floor and I think it has to be within a certain distance to a floor drain.
 
You never reduce the size of the NPT on either side of a PRV. It is acceptable to increase size of pipe on discharge side from what is on the PRV but never to reduce. The tapping for the PRV should match the size of the NPT on the PRV. !/2" is extremely small. Also PRV should be located as close as possible to boiler. Best practice's is to have no more than 2 elbows on the discharge side.
 
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