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SBboiler

I am replacing a steam boiler that used to supply steam for 3 air handling coils and a heat exchanger in a tank for domestic hot water generation it was installed back in the 50's. Now all it supply is one 6' X 8' heat exchanger for an air handler. I have been subcontracted out to install a new 880,000 BTU low nox boiler that has already been purchased by customer. They sized thenew boiler by the original two boilers combined btu output when buying the new one. I have two concerns and was looking for some advice . First I am concerned the burner will short cycle due to be oversized, this I can deal with . Secondly the existing steam supply header is 3" but that was for two boiler could I run it in 2" since all it supplies is the air handler now.  Or should I just pipe it in 3" as the book says , I am not trying to be cheap  just not wasteful . The supply and return for the air handler are only 2" black  so does that not regulate my supply rate . Any feedback would be appreciated.

Unknown

My 2 cents,,,,

Man,,, that is SO stupid for anyone to size a boiler for a load that is not there!!

Will it short-cycle?,,, you can bet on that!



As for near boiler piping,,, follow to the "letter" what the boiler manufacturer recommends, then get the "hell" out of there!

PS- Make sure(in writing), this sizing was their doing. ;-)

Charlie from wmass

3" is small for that boiler

4 to 6 sounds more like what is called for. Did they save the receipt? they need to return that beast.