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Sizing a Replacement Steam Boiler Based on Building Heat Loss-NBP w/3 Drop Header Piping Diagrams
I need to do a proposal to replace a 1955 schoolhouse Kewanee NG , nameplate of 1,080,000 BTUH input.
It has 2 zone valves (1 for old 1 pipe and 1 for newer 2 pipe) with a total of 1756 EDR connected.
Because of building improvements and radiation removed we are just about oversized by 2X.
First questions are about doing the room by room heat loss.
Using the simple Guide 2000 part 2 from the I=B=R guide, I am getting about 36 to 48 BTU/sq foot.
Also working backwards from installed EDR X240 and comparing that to my results I get a fairly consistent indication of new heat loss to be 65 to 73% of installed max EDR available.
The big variable is always the infiltration factor. I used 1 1/2 ACPH (.027 factor).
The build is fairly tight for it's age. In all the 6 class rooms to be heated, 168 sq feet of single pane windows have been replaced with insulated 2 x 6 walls that have 40 sq feet of double pane casement. The remaining walls are 12" of brick.
The ceiling has went from 1" 1955 roof "insulation" to 12 inches of blown in attic insulation.
Room sizes are from 620 to 814 sq feet with 10' ceilings.
So far does this seem to be way off base? Thanks in advance.