steam help needed

STEVEN MARKS

I am presently investigating steam probelms in a 24 unit apartment building.
I have replaced some disc traps,radiator valves, lowered the pressuretrol setting and now have most of the radiators working coreectly.
All but 3 are now working. I have replaced the traps. If I open the trap at the radiators and start the boiler the radiators will get hot. I then tested the condensate returns by disconnecting the traps and filling the condensate returns with water. All seem to be draining correctly.
Long term tenants tell me these radiators have never worked.
The boiler is located in the center of the building with 2 steam mains running the length of the building in opposite directions.
There are no main air vents at the end of mains. At the end of each main is a 3 x 1/2" tee that goes to a thermostatic trap (above the mains). This is the condensate return line for all the radiators.
There is not a F&T trap at the end of the mains. The pipe elbows to the floor. Essentially 2 condensate returns. 1 overhead and 1 at floor.

Steamhead (in transit)

Sounds like a Vapor system

when you opened the traps, did any air come back at you from the return line?

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STEVEN MARKS

Steam

No. When I opened the traps no air. The radiator slowly began to heat. I tested the drains and they seem to be working. I earlier posted this is 24 apartment but it is only 12. This is an older Mills boiler and I found to be fired at only 2 gph. I am thinking maybe it is underfired?? Does this sound possible? Steam boiler to small so not all the radiators heat? The condensate returns never seem to get warm.

Steamhead (in transit)

Could be

what is the boiler's rating, and how is it being fired (burner type, lo-hi-lo?)?

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Kent_3

If, when you open the traps on the three radiators

that aren't heating correctly, and the radiators then get hot, it indicates that those traps, new or not, are plugged. Also, see that your pressure is next to nothing. I once heated a row of fourteen greenhouses with the gauge reading zero pressure (and the gauge worked)!