More help sizing a replacement boiler.

Michael Gulich

I am replacing my steam boiler in a 3 family, 3 story wood frame, cement stucco finish house which dates from late 1890s. The system is a one-pipe system. The current boiler is only 15 years old and gas fired. It cracked last winter because the auto feeder and probably the low water cutoff failed. I was not diligent last year in flushing out the low water cutoff and keeping an eye on the water level, an expensive lesson. I have measured all 18 radiators and come up with 525 square feet or 126,132 btu. I am planning on adding a radiator in the future at a location where one was removed (so the piping is just plugged). The steam mains have been reinsulated (by me). What pick-up factor should I use? The existing boiler is a Utica 262,000 input and 212,000 DOE. My plumber is suggesting a Weil-McLain EG-75S 300,000 input, 240,000 DOE boiler because there are 18 radiators, and his rule of thumb is 40 square feet per radiator which gives him 720 square feet. I am worried this will be too big and maybe the EG-65S (250,000 input and 203,000 DOE) would be a better choice? What is the consensus on the Weil-McLain's in general? Thank you in advance for any help.

Michael

Michael Gulich

Location.

The house is located in Montclair, NJ.

clammy

pick up factor

with edr of 525 and a pick up factor of 1.5 my math comes up with a 189,00 btu output boiler.to oversize the boiler will leave you with a boiler that short cycles all the time check your numbers again a 300'000 btu boiler sounds a bit large.please make sure all your near boiler piping is done right and insulated,mclean is a desitent steam boiler some perfer peerless i like mclean because of there off the top connection instead of side outlets all of the boiler manafactors will give you header sizing diagrams for there unit don't settle on copper header do it right with steel and swing joints on the header good luck just my 2 cents

JohnNY

Any particular reason?

Any particular reason why the plumber is using a rule of thumb instead of real calculations?
Overwhelmingly, replacement boilers tend to be smaller than the originals.
In my opinion it is well worth the hour it takes to do the math.

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Mad Dog

The guys are 100% right! no rules of thumb......................

this is 2003....The Lost Art of Steam Heating has been in print for many years. The plumber needs to buy a copy. You cannot beat a Burnham Steam boiler my friend. I commend you on being diligent and vigilant about sizing. You might want to try Find A Contractor at this site to find a good steam, guy in your area - not a rule of thumb fellow. Go Burnham! Mad DOg

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