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# sizing a steam boiler

Member Posts: 1
i did a radiator sq footage brake down and came up with 370 sq ft that with 10% for piping what is the next step to find the input btu somthing about multiplying the appropriate emission rate by total sq ft how do i find emissions rate thanks dan

• Member Posts: 23,905
BTU per square foot

multiply the EDR by 240 to get the net BTU you need at the radiators.  Then I would use a 1.33 pickup factor to get the BTU output of the boiler.  Most boilers also have net I=B=R output rating for a particular size shown.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 1,568
in most cases ..

you can stop right at 370 .. and check the sq ft of steam that the boiler rating shows. this rating includes 1.33 for pickup factor and unless you have an exotic pipe system, 1.33 should be fine.

next questions are fuel type? gas? oil? dual? other? tankless coil or not?
1-pipe Homeowner - Queens, NYC

NEW: SlantFin Intrepid TR-30 + Tankless + Riello 40-F5 @ 0.85gph | OLD: Fitzgibbons 402 boiler + Beckett "SR" Oil Gun @ 1.75gph

installed: | gortons on all rads | 1pc G#2 + 1pc G#1 on each of 2 mains

my NEW system pics | my OLD system pics
• Member Posts: 4,343
Do as Jamie says.

From someone who does this for a living the 1.33 factor seldom makes for an over sized boiler and seldom is "normal" piping normal.
Cost is what you spend , value is what you get.

cell # 413-841-6726
https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
• Member Posts: 1,568
confused...

how are the methods above different. my method simply requires 1 less bit of math (sf X 240 X 1.33 = BTUH Output) but the boiler ratings already do this math in their sq ft column. so i'm not sure how Jamie's method is different. I was simply reiterating steamhead's advice to me in his post/thread here: http://www.heatinghelp.com/forum-thread/128987/oil-now-gas-later#p1183969 I think he also does this for a living.
1-pipe Homeowner - Queens, NYC

NEW: SlantFin Intrepid TR-30 + Tankless + Riello 40-F5 @ 0.85gph | OLD: Fitzgibbons 402 boiler + Beckett "SR" Oil Gun @ 1.75gph

installed: | gortons on all rads | 1pc G#2 + 1pc G#1 on each of 2 mains