Service Manager

cd56

I looked at a job to replace a boiler I installed years ago. The house was sold and we didn't have the account for twelve years. I got it back and it's leaking due to lack of maintenance. The job looks like figure 56 page 266 in the lost art of steam. The gasket on the return trap and the Hoffmann #30 are leaking. I want to pipe it as a conventional two pipe steam boiler with a main vent before the end of the main. I don't see the need for a trap as the dry return will go to the floor before being piped to the Hartfored loop. Question is am I right?

Jamie Hall

I have mislaid

(again!) my copy of Lost Art, but if you have dry returns, and you bring them below the water level of the boiler, they turn into wet returns -- and then you can join them and pipe them as you please, so long as they stay low until they get to the Hartford Loop.  You don't need a trap or check valve or anything of the kind in that situation, provided -- and this is important -- that the rise from the water line in the boiler to the steam mains is at least 28 inches.



You do need a vent on the ends of the mains.

Steamhead

On that type of Hoffman system

the radiator trap between the steam main and the dry return is the steam main vent. If you eliminate this trap, you need a vent on the steam main.



Whichever way you go, you also need a vent on the dry return.



If you control the boiler pressure with a Vaporstat, you can remove the leaking return trap.