2 pipe vacuum system without traps

Steamhead (in transit)

Boilerpro is probably right, it sounds like an Orifice Vapor system, where the pressure is kept very low and the amount of steam limited by orifices so no steam would make it to the dry return.

The orifices in the convector elements were often cast integral with the headers near the pipe connections.

Keep the pressure low with a Vaporstat, vent the mains and dry returns well, and it will heat quickly, quietly and evenly.

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C.Carbone

2 pipe vacuum system without traps

I am dealing with a 2 pipe vacuum system. I did not find any steam traps anywhere so I suspect the return elbows on the 3 free standing radiators might be the double tapped type. The rest of the house has in the wall convectors where the return pipe goes straight down through the floor. I found 1 American Radiator #822 Ideal Vac Valve at the end of 1 return. The other return is buried in a wall or ceiling of the finished basement. Is is possible there are no return traps on this system? I see maybe if the radiator elbows are the double tapped type, but what about the convectors? I explained to the homeowner that I believe this system was designed for the old coal burner that was once there & now there is an oil fired hb smith boiler that is about 15 years old put in by the previous owner. Anyway, any thoughts about the absence of steam traps and any ideas on how to get this system to work better. I repaired one leak on a supply union which may have been causing the system to lose vacuum, but I am not aware of any other leaks or spots where the vacuum is breaking.

Boilerpro_5

Where to look

Many systems have orifice plates in the valves to limit the amount of steam entering the radiator so traps were not needed....as long as the pressure was properly controlled. If not plates they may have special orifice type valves with orifices built into the valve. I understand there are hundreds of two pipe steam systems that have been converted to orifice plate systems in the past few years by knowledgable contractors. What a great thing, eliminating all that maintenance associated with traps at every radiator.

Boilerpro.

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C.Carbone

If i vent the mains won't I be breaking the vacuum & therefore stop the flow of the steam? The vent on the return says Ideal Vac Vent. There are no dry returns, at the end of the run the supply elbows down to the floor then becomes the wet return.

ttekushan_3

I suppose you could

install 1 or more Hoffman #76 non-return vents. They incorporate a ball check to prevent ingress of air.

-Terry

Steamhead (in transit)

Don't need vacuum vents

they only work well with coal firing. The dry return on this system handles the air and condensate from the radiation, and needs to be vented also.

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