Pitching Radiators / 1 pipe steam

ksd99

When I got the house last fall, my radiators knocked - I pitched then and the noise stopped mostly. We recently removed a radiator from the pipe to fix the floor underneath it and being curious I stuck my finger in the radiator - there was a fair amount of water in it. So I decided to pitch the back end, appx 1.5’’, and I put a cup on the valve side...i bet there was appx 3 tables spoons of water which I initially thought was a lot because I thought all the water had to leave the radiator to prevent knocking. Is that normal for some water it sit in the radiator. This particular radiator starting knocking at the beginning of the heat cycle towards the end of winter which could be because of the collection of water. Thoughts? I would be concerned about pitching a radiator that much thinking might brake the pipe.

ChrisJ

All of my radiators have water in them.
A few, are pitched the wrong way.

None of them make a sound.

How fast are you venting? How are your main vents and how is the boiler piping?

Jamie Hall

More likely the problem is that some pipe feeding that radiator is pitched slightly the wrong way -- knocking at the beginning of a cycle is almost always condensate forming in the riser or runout as it heats up and making a nuisance of itself until the pipe is warm enough to stop condensing much. Check the pitch of all the pipes going to that radiator.

Fred

Typical cast iron radiators have a "trough in the bottom of them that sits below where the pipe connects. That will catch debris and also hold a little water. That is normal. It should not cause any noise, if the system pressure is low and the radiator venting isn't too aggressive.

ksd99

Thanks Fred.

ksd99

Thanks Jamie