Source of Water Hammer

MrVince

I am experiencing water hammer at a specific radiator on a 2nd floor. I think it's caused by a slight dip in this basement supply pipe before it goes up the riser. It's shown in the picture below.



Is there an easy fix to this? I can't seem to raise the radiator on the 2nd floor.

Alternatively, what's a way to fix this even if it's difficult. Would it be to undo the fittings and reattach them? Slightly decrease the slope on the left supply in order to give a slope on the pipe with the incorrect slope?

ethicalpaul

Some kind of repipe will be required if you really can't lift the radiator... I had the same problem and I ran a new riser. See my saga here: https://forum.heatinghelp.com/discussion/167233/fixing-pitch-issues-in-old-house#latest

You could also run a drip line down from there to the wet return. As long as it drops to below the water line it would be OK I think, but I see you have very tight working quarters there so I don't think that'd be any easier.

Have you tried lifting the radiator very slowly, like 1/4" every few days using a lever and shims/boards? It probably took decades for it to settle to this position, it will take time to lift it back up.

EBEBRATT-Ed

These problems can be difficult to track down. Somewhere water is hanging in the pipe or the radiator. the pipe and radiator should be pitched so all the water drains back to the boiler.

Where are you hearing the banging?

MrVince

I'll give it another shot with lifting the radiator, trying to lift it over time. The problem is that it's almost impossible to get a grip on this radiator. The bottom cover is stuck in place because floor tiles have been installed in front of it. But, I'll definitely give it another go and let you know what happens. Thanks.

ethicalpaul said:

Some kind of repipe will be required if you really can't lift the radiator... I had the same problem and I ran a new riser. See my saga here: https://forum.heatinghelp.com/discussion/167233/fixing-pitch-issues-in-old-house#latest

You could also run a drip line down from there to the wet return. As long as it drops to below the water line it would be OK I think, but I see you have very tight working quarters there so I don't think that'd be any easier.

Have you tried lifting the radiator very slowly, like 1/4" every few days using a lever and shims/boards? It probably took decades for it to settle to this position, it will take time to lift it back up.

MrVince

In the picture, the right pipe is the one with the wrong slope. So, the water hammer is likely caused by this. This line is where the banging is coming from.

EBEBRATT-Ed said:

These problems can be difficult to track down. Somewhere water is hanging in the pipe or the radiator. the pipe and radiator should be pitched so all the water drains back to the boiler.

Where are you hearing the banging?

Hap_Hazzard

I had to do this once. It was a little more accessible, so I don't know if this will work for you, but I used a pipe hanger with a turnbuckle instead of a straight threaded rod and, as ethicalpaul suggests, kept tightening it gradually and making sure I wasn't just breaking the joist I had it hanging from.

ethicalpaul

Oh and I should add that there is likely a horizontal section in the floor where the radiator is, so it may indeed may be impossible to lift the radiator enough to affect that downturned pipe. That was my situation so that's why I had to re-run the pipe.