Steam radiator sounds diagnosis

jweob

I have a tenant who is having trouble sleeping because of radiator noise in their bedroom. I'm hoping you can help me diagnose the two types of noises they are hearing and suggest anything I can do to fix.

They have complained of two types of noise which are in the videos below:
"Banging"
"Water noise"

It's a 1-pipe steam system in a 4 story + basement townhouse. Boiler is an EG-75 Weil Mclain. There are two runs from the boiler, both with working bigmouth main vents (but the vents are on the mains in the basement, not at the end of the risers). The problem radiator is the closest radiator to the boiler - it's on the ground floor. The supply valve is fully open and the Gorton vent appears to be working fine. It has a good amount of pitch. There are three other radiators on the floors above it on the same riser. The other radiators do not make these sounds.

The boiler pressuretrol is turned down to the lowest setting and differential, but is actually cutting out at 3.4 psi (see here). The boiler seems to be behaving itself otherwise. I recently drained it and water in the eyeglass is clear, no apparent surging. The main pipes in the basement are uninsulated, and the main pipe going to the problem radiator riser does pass under the combustion air inlet for the basement so does get some cold air on it.

My guesses are as follows:
* The "banging" sounds are thermal expansion, and I can't think of anything I can about them
* The "water" sound is condensate failing to drain, I'm guessing because the pipe going to the radiator might not have enough pitch, but maybe the supply valve itself is busted.

What I'm going to try is:
1) Calibrate the pressuretrol to bring the cut-out to 1.5 psi (less steam = less condensate to drain)
2) Insulate the main pipes in the basement in case too much condensate is being picked up there
3) Raise both legs of the radiator 0.5 inch to see if I can force better drainage
4) In spring, undo the radiator and check the supply valve (I don't dare do this in winter)

What do you think - am I on the right track? Anything else I can try?

Jamie Hall

All of your ideas will likely help some (though be aware that lower pressure does not mean less steam or condensate -- the amount of condensate depends on the size of the radiator, not the pressure, and lower pressure means the steam can move faster). Your 2 and 3 have the best chance of helping.

If the banging is really thermal expansion it will be limited to when the heat is coming on or stopping. See if you can find locations where pipes are rubbing against something (floors for instance!) and if you can slip something like a piece of poly milk jug in. That sometimes helps.

jweob

Photo of pipes near the radiator and the near-boiler piping

jweob

Thanks @Jamie Hall, did the first video sound like thermal expansion noises to you? Do you have any other ideas what it could be? I thought maybe water hammer but doesn't sound loud enough?

Grallert

I thought I heard a bang followed by expansion noise in the first video. That bang would seem to be hammer. Both can happen on start up. If water isn't getting out of the radiator fully when the steam arrives that's the bang. That's what I heard.

Jamie Hall

That first one does sound more like expanson.

That horizontal runout in the picture could be pitched too flat, or even backwards, and make all kinds of mischief -- and since it is buried in the ceiling...

jweob

Well, I discovered that when I thought I turned the valve all the way open previously I actually turned it all the way closed, so that certainly wasn't helping. I don't think that was the main cause though since the radiator was still heating up regardless and the tenants complained of the sound in the previous position as well.

I've now actually opened the valve. I raised the radiator about 1/4 inch on both sides (couldn't do more it seemed caught). I calibrated the pressuretrol to actually cut out at 1.5 psi, and I got a tube of fibreglass insulation over most of that runoff in the ceiling just by pushing it along the pipe.

If the noises are still there then I will cut out that ceiling drywall and check the pitch of the runoff pipe.

Any other advice gratefully received!

mattmia2

On 1 pipe steam the valve being mostly but not all the way closed will cause the radiator to hold condensate. When the steam hits that condensate it likely will bang. The valves on 1 pipe steam must be all the way open or all the way closed.

mattmia2

Where in the cycle the sounds happen can be a clue too. My guess is the gurgling is before the steam reaches the radiator as air is being pushed out it gurgles then once steam is pushed in to the water it hammers.

BobC

Put a level on that radiator and make sure it's pitched towards the steam ilet pipe and valve. If it's not pitched add a shim under the air vent end to give it some pitch - use a 2x4 to lever the end up and be gentle.

Bob