Buderus GB 142-30

caulksoaker

I'm looking for some help. The city wants me to reduce the PSI's on the 'pressure relief' valve of my GB 142-30, significantly. The GC who built the building and i agree, that for a 63' tall building, with a straight run of pipe, the Penthouse apartment radiators would not work properly with a reduction in the PSI valve. Does anyone have any hard facts about the correlation between PSI's and building height?

SWEI

The height that actually matters is measured from the circulator to the highest point in the system (often a radiator.) The recommended static charge pressure of the system would be that height (in feet) divided by 2.31 and then add 4-5 pounds.

If that number comes out above 30 PSI (which it may well for your building) then the boiler must be rated for more than a 30# relief valve.

lchmb

What is it now and what do they want you to drop it to?

Rich_49

The max pressure rating for a GB142 is 44 PSI . Considering a 63 foot height is accurate + 5# you'll need a cold fill pressure of 32.3 # . This height should only be from , as Swei stated the elevation of boiler / circ to the highest radiation .

The max pressure for the boiler can be found on page 7 of the IOM that came with the boiler . Watts 174A - M3 set for 36# should get you there but I don't think that is your problem . You probably already have a sufficient relief valve and just have an inspector problem . There is probably a code in place that also states that the ENTIRE building must be able to be heated . Ask him how he proposes you accomplish that feat without the required pressure . Thats all far fetched though , maybe he just needs to see the manufacturers specs for the equipment and that 44# is acceptable .

http://media.wattswater.com/ES-174A-740.pdf

http://www.bosch-climate.us/files/GB142_IM_72150200_2013_US.pdf

caulksoaker

I currently have a 50 PSI Relief Valve in place and the 'Inspector' wants a 40, eventhough the Buderus spec sheet says 43.8 or some such. Here's a question...how many increments of Relief Valves are there? Do they drop by 2 PSI's or 5 or 10?

Rich_49

The inspector is right . A 50# valve certainly does not meet the criteria for that boiler and would allow the boiler to exceed max pressure by 6# , no good my friend . Quite simply put , 50# is greater than 44# . A 40# valve set is sufficient for your install based on what you have offered us . Make sure the expansion tank is charged to the cold fill pressure PRIOR to re filling

caulksoaker

hmmm. interesting. where do you guys purchase these valves for Buderus? can i just call 'Apollo' and get one for 40 PSI?

SWEI

McDonnell & Miller and Watts both have 40 PSI options. Probably others as well.

Zman

The other thing the inspector will likely be looking at is that the Btu rating on the valve exceeds the rating on the boiler.