Cold radiator, 2 pipes both hot

Rmasci

So I manage an older 3 story building with 2 pipe steam radiators.

I have a curious issue where in a basement unit the tenant says her radiator is not getting hot. So I have been in here today, the valve is new as is the Hoffman trap. With the boiler on steam makes it's way into the supply pipe as it should but the radiator refused to heat up. Before I left I noticed the hoffman trap for returning condensate and it's pipe were scalding hot as well.

What could cause this?

Jamie Hall

Almost certainly either a failed trap somewhere else on that dry return or, just possibly, a water seal between the steam main and the dry return which is not wet (blown from excess pressure, or connected to a wet return which has been dried out due to a changed boiler water level). You may be able to find the failed trap if you can trace the dry return back.

Rmasci

So this is the lowest radiator on the riser. Is it most likely one of the three radiators above it on the same riser?

Jamie Hall

Rmasci said:

So this is the lowest radiator on the riser. Is it most likely one of the three radiators above it on the same riser?

Might as well start there, anyway.