can't identify cause of noise in radiator

StevenRubin

The 1-pipe steam radiator in my bedroom makes a lot of racket as soon as it gets steam, which is usually at about 4am. It’s infuriating. The thermostat is set to come on at 64F and off at 66F. I put on a new Hoffman vent. I have the radiator pitched towards the supply valve. I checked the valve body to see if the seat/gasket came apart and might be blocking condensate flow (it not, and its fully open). I stuffed pieces of plastic milk carton around the supply pipe and hole through both floors it passes through. I traced the horizontal pipes in basement and verified that they all slope towards boiler. I verified that steam pressure is 0.5 with a differential of 1.0. I verified that the pig tail is unobstructed and that the water is clean and not surging. As soon as steam gets to the radiator, it starts pinging. And I do not mean little quite pings but more like someone whacking the plastic handle end of a large screwdriver on a radiator section. After about 80 pings (about a ping per second), it goes quite for about 2 minutes, then the damn pinging starts again, but maybe about 50 pings this round. Then it goes quite for a minute or two, then the pinging starts again one last time, maybe about 15 or 20 pings, then it gloriously goes quite for good. Of course I am now fully awake and pissed off and can’t go back to bed. I can’t just switch the offending radiator with another in the house, because the others are in in my kids rooms, or are downstairs and the damn thing weights about 500 pounds and I am old. Am I overlooking something? Maybe the sections have gotten out of whack? The nuts on the tie rods are coated in about 120 years of paint and rust. Do I dare to mess with those? Should I just move?

Jamie Hall

It can be annoying... it's an expansion noise, most likely in the radiator. Have you put plastic under the feet of the radiator? I assume you have, but if not you might try that.

The tie rods might have gotten loose over the years. But with a lot of paint on them, playing with them is a little risky (they break dismayingly easily). However, if none of them actually rattle when you wiggle them, that's probably not really it.

JUGHNE

Water hammer can telegraph thru piping from another part of the system.
Can you feel your rad valve get hot when it starts?

If it is for sure your rad, the only thing I can think of is to shim up the end, opposite of the steam valve, more than you already have.....maybe another 1/2".

acwagner

Is this a long radiator? If so, it's possible it's sagging in the middle.

Danny Scully

Sounds like it’s new radiator time. Problem solved!

AMservices

What size is the supply pipe and what is the EDR of the radiator?
I'm wondering if the radiator has been changed once before. If the rad is over sized for the supply, it will condense steam faster then the supply can drain it back out, with incoming steam.
For example:
If the supply pipe is 1", the radiators EDR should be no greater then 28 or 6,720 BTU.

Fred

Are all four of the radiator feet solid on the floor? Sometimes if one foot is not touching or barely touching the floor and not sharing its share of the weight, the radiator can twist a bit as it expands/contracts.

EBEBRATT-Ed

Maybe slowing down the venting will help. How does it heat the way it is? Also I would check the edr of the radiator against the pipe sizing of the branch as @AMservices mentioned

New England SteamWorks

Increase main venting, slow down that radiator venting, and pick a temperature and stick with it. That will probably make it quiet. Thermostat set-backs with steam tend to cause problems.

StevenRubin

Thanks to all for your suggestions. To AMservices , its a 1" supply, but I do not know the EDR. However, I have great news, problem solved. I took the risk of tightening the tie rod (mine have just one rod, near the top). It was not overly loose, but it did take nearly a full turn to get it to just a bit more than snug with an open end 11/16 wrench. I thought some might find it useful to know the torque, so I measured it. 22 foot pounds. I went around to all radiators in the house and did the same. They are all blissfully silent. I am astonished. I should have done this years ago. Life changing moment.

AMservices

@StevenRubin Nice work. And your reward is a full night's sleep.
Have a good night