One radiator not getting as hot.

realmiked

One pipe gas fired steam heat brand new boiler.
I have one radiator on my first floor farthest from the boiler that gets only partially hot while the other 3 rads on the floor go full steam ahead(pun intended). I have checked other discussions on here about same topic with some saying it could be vents on radiators or on boiler pipes in basement. One thing I did was close valves on all other radiators on the floor and then that one radiator gets fully hot like the others normally do when open. I would assume this means its not the valve on the radiator am I wrong? Thanks

BobC

Steam will always take the path of least resistance. Your test proves there is a path for steam between the boiler and that radiator, it does not prove out the valves.

In general you want to vent the mains as fast as you can and the radiators slowly. There should be enough slope so any condensate can find it's way back to the boiler, water should not be able to sit in any level or mis-sloped pipes because that will condense steam.

I assume this room ti cool and that is why you've investigating it. We need to know a few things -

Is there only one steam main?

How long is the steam main and about what size is the pipe?

What kind of main vent is on that main?

What size is each radiator and what kind and size of air vents are on each radiator?

Have you gone over all the horizontal piping that feeds this last radiator (including the portion of the main) to make sure it has proper slope - nu places for water to sit and condense the steam?

Bob