Boiler with no TPRV?

[Mike Lamb]

I looked at an old 1970s Bryant boiler and could not find a TPRV. The only accessible panel was at the front burners. Might the TPRV be hidden somewhere inside the unit? Is it possible there could be no TPRV?

[mjr6550]

I looked at an old 1970s Bryant boiler and could not find a TPRV. The only accessible panel was at the front burners. Might the TPRV be hidden somewhere inside the unit? Is it possible there could be no TPRV?

]

Yes. I have never seen one hidden. However, on very old boilers they are in the piping and not on the boiler. That would be about 1950's? or older.

[Chad Fabry]

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Some PRV's don't really look like PRV's

[Hearthman]

Yep note on boilers they only require a pressure relief valve and not a temperature/ pressure relief valve. ASME provides some flexibility as to location but on commercial applications the insurance underwriter and state boiler inspector will probably be very strict applying CSD-1 to relief valves. Also, they should be tested per mfr. and replaced very few years even if they appear to be working properly. Some mfrs. used to state about every 5-7 yrs but some of that has changed. The relief must match the max. rating on the rating plate. Very tall buildings may use 50 psi instead of the typical 30 psi for hydronics. 5 psi is typical for residential steam boilers. Note a 50 psi system would require a higher rated automatic fill valve and backflow preventer, too.

[mjr6550]

Maybe a typo, but residential steam boiler relief valves are 15 psi.