near-boiler piping

Unknown

I have to replace both steam boilers in a two (up+down) family house I own.  Both floor plans and radiator layouts are identical.  I photographed the radiators on the 2nd floor and brought them to my supply house.  The connected load for each floor was calculated by them as 305 sq..  The recommended replacement boilers are Burnham MST-396.  The existing boilers are Arcoliner 2BT-J3 rated at 360 sq. ft of steam.  The system for each floor is a counter-flow with 2" mains.  And I'm aware I have to supply to the top of the main unlike the way it is now.

My question is: Does it make sense to increase the the supply from 2" out of the boilers to 3" up,over and back down to 2" into the top of the mains in order to reduce the velocity of the steam from the new boilers entering the undersized mains as well as to improve the dryness of the steam.

Thanks,

Walter

RDSTEAM

do you mean

run 3" to the 2" mains and then reduce the size?? just run your 2" boiler takeoffs to a 3" drop header, you will be fine.

Charlie from wmass

Walter how did you size your boiler?

I am sure the Arcoliner rating is pretty big for most duplexes I see.

The one I live in with my girlfriend is under 170 square feet of steam for each unit.

Charlie from wmass

To answer your question though

With a counter flow system a 3" drop header or at least a 2 1/2" drop header is good if you do not have drips where the supply ties into the header.