Pipes are Hot - Radiator not?

RayP

I had a plumber replace some valves on my old radiators because the would not open/close. They also moved a radiator from one spot to another as we are doing some renovations (this radiator works fine). One radiator will not heat up and I'm having REALLY LOUD steam hammer problems now. In the basement, the pipes from the boiler up to this radiator are smoking hot, but no heat comes up at all to the radiator. Radiator is pitched very hard towards the valve and there is not enough valve pipe to tilt it the other way at all.

Called the plumber back in, said he wanted to raise the pressure of the system, I read the book so I said no way, he then suggested that we do a "skim tap" to the boiler? Not sure how that will help get steam into the radiator?

The system was working well until the valve was replaced? The other radiators are working fine (valves replaced as well), except they are releasing a lot of air, I assume it's because the one radiator is a bit off? I took the radiator off to check for blockage in the valve - did not see anything bit there was about a cup of water in the radiator that I poured out. Any ideas what would stop the steam from coming up?

BobC

Pipe pitch has to be right

Is this single pipe steam?



If so there is an air valve on the side of the radiator about half way up, if that air valve does not ope to allow the radiator to vent then steam cannot enter the radiator.



Because you mentioned the water hammer make sure all the piping that supplies that radiator is pitched so the water can find it's way back to the boiler. If that new valve is causing a problem with the slope then a nipple has to be added so you can get the pipes all sloped correctly, at that point you may have to block the radiator up for everything to work out.



Any water pooled in the pipes will condense the steam and can cause water hammer. If it's 2 pipe steam everything should be pitched from the output side back to the boiler.



Bob