Banging radiator after relocation

Does anyone know of any tricks I can use to mitigate a banging radiator? I get water hammer in one of my rads after it was relocated. I’m pretty sure the piping was laid down incorrectly. I’ve tried raising the rad up from the inlet side and have pitched the rad back towards the inlet from the other side also. For whatever reason over venting the rad helps in banging. Any other tricks I can try? If all else fails would a smaller rad or a steel convector help? 

Just a thought... I had one long radiator that would always clang when heating up and then once more upon cooldown... Couldn't get it to stop despite replacing tension rods, replacing piping, and adjusting for proper pitch of the radiator. I lived with it like this for years. Last year I put a 5/16" washer under each foot and it totally resolved the clanging. I think the radiator was binding with the wood floor. The washers allow the radiator to "slip" on the floor to allow for proper expansion and contraction.

Thank you for adjusting the thread. Well the radiator in question is on tile flooring so I think I can rule out binding. Also I can hear water in the pipes and radiator swishing around. 

Jamie Hall said:

Actually, no -- the feet of the radiator can stick and slip on the floor. And often do. However, if you can hear water in the pipes... there you are. Now the question is... how to fix the pitch so it isn't there?

Ahh ok I see. Well I have raised the radiator from both ends in an attempt to correct the pitch of the pipes and have placed wood under the feet of the rad. Also pitched the rad back to the inlet also. If I try a smaller rad, would a small steel convector be better in any way vs a actual rad? 

If you moved the radiator and have more than 6 feet of the original sized pipe the condensate will not drain fast enough and
steam will stop the flow of the condensate and banging will occur
Two corrections are possible.
1. try to get at least 4" of pitch on the horizontal supply to the radiator.
2. Increase the size of the horizontal pipe one size. That would entail replacing the the riser elbow one size (example 1 1/4" X 1 1/2" elbow with a piece of 1 1/2" pipe and at the radiator supply reduce from 1/1/2" pipe with a 1 1/2" x 1 1/4 Elbow to supply the radiator and Pitch the pipe with at least 1/2" of pitch ).

Jake

ss8295 said:

If I tap in a vent on the same side as the inlet valve on the problematic radiator, would that essentially make it act as a smaller radiator? That way I can simulate if a smaller rad mitigates the problem. 

Sadly, no. All that will accomplish is to make it heat faster -- and quite possibly make the problem worse.