A crossover trap at the end of the dry return?

Double D

This system is an Arco Model K vapor orifice system, exactly as it's pictured on pages 268 & 269 in LASH. I'm able to see one of the 2 mains in it's entirety however the other main is completely enclosed in a soffit that runs through a finished portion of the basement. The existing boiler is using a condensate return pump. There are 2 traps on the dry return behind the boiler. One is a Hoffman 17C at the end of the dry right next to a Hoffman 76, the other is a Hoffman 8c being used for a coil inside of an Arco blower unit. The 17C makes no sense at all. The owner would like to install an A/C unit in its place and hook up to the existing supply & return duct system. I'm not getting the idea they are thrilled about opening the soffit to vent the main buried in it. I'm assuming the mains were venting into the condensate return pump through the once wet now dry return. When I disconnect the pump and make that wet return wet again I'm probably going to need to vent both of those mains, correct?

Jamie Hall

Are there crossover traps at the ends of the steam mains going into the dry returns, and not a direct connection between the steam mains and the dry returns? That's how it should be -- and if so, then you only need one main vent or main vent cluster at the end of the dry returns where they turn down to go back into the boiler.

Double D

@Jamie Hall The one end of main that I can see in the laundry room turns down to the wet return. There is not a direct connection to the dry return. There is no crossover trap or vent. I would be able to get a crossover or vent at the end of that main.

Jamie Hall

Do. Either one, though a good big vent or vents is probably easier.

Double D

If I'm able to get to the main that is buried in the finished portion of the basement I would feel better using a crossover trap. If a vent were to fail, they might not ever know until it's too late. As always, thanks for your help @Jamie Hall

Jamie Hall

Double D said:

If I'm able to get to the main that is buried in the finished portion of the basement I would feel better using a crossover trap. If a vent were to fail, they might not ever know until it's too late. As always, thanks for your help @Jamie Hall

This is so true...