Loud clicking noise every night

jjmcna10

I live on the second floor of an 100yr 3-family house in Boston. We have 5 radiators that are fed from a steam boiler in the basement. The radiator in my bedroom, which is the furthest away from the central pipe leading downstairs, emits a loud ticking or clicking noise whenever it turns on. I have a video of the noise it makes but not sure I'm able to post here. It wakes me up almost every night and I've resorted to cranking the heat up before bed, turning it off and waking up freezing. The radiator is pitched correctly and I've already tried a new air vale (vent rite #1). Is there any solution out there? I've spoken to a few plumbers over the phone who said there's unfortunately nothing they can do.

ethicalpaul

How far apart are the occurrences of the "ticks"? Has steam reached the radiator when the ticking starts? How soon after the steam arrives at the radiator does the ticking start?

You can tell steam has arrived at the radiator when the valve gets "steam hot" (too hot to hold onto for even 1 second)

jjmcna10

@ethicalpaul The clicks are about 4-5 seconds apart. The steam seems to be reaching the radiator and then then the clicking starts.

Here's a short video of the noise it makes

ethicalpaul

I have one that is doing this. It comes down to two possibilities:

1. Expansion of the radiator joints
2. Water hammer caused by steam coming into contact with cool water

I think yours is #2 but I'll be interested to see what others think.

How is the level of your radiator when measured with the level lying on the top from side to side? It should slope slightly toward the valve side. EDIT: I see you said it was pitched correctly. So it is definitely pitched toward the valve side? (the pipe side, not the vent side that is)

kenlmad

It sounds like gaseous steam and liquid water flashing or collapsing in a fight to reach instantaneous thermal equilibrium.

mattmia2

Is the valve open all the way? Does it happen the whole time that it is heating or only until it gets hot?

ethicalpaul

kenlmad said:

It sounds like gaseous steam and liquid water flashing or collapsing in a fight to reach instantaneous thermal equilibrium.

Indubitably, a distinct possibility old bean, wot wot?

jjmcna10

@ethicalpaul It's pitched towards the the pipe coming out of the floor, in other words the side with the adjustable air valve is slightly higher than the side with the connection to the floor

jjmcna10

@kenlmad I no do so good in school. Can you rephrase this for a layman?

jjmcna10

@mattmia2 the valve is currently open all the way and the clicking last for about 2 minutes during the heating up process. It then stops clicking and the radiator continues to get/stay hot

I've noticed the vent rite #1 sometimes sucks air in and other times pushes air out. From what I've read this is correct, though I'm clearly no expert

JUGHNE

It sounds like mild water hammer to me.
Perhaps raise both ends of the radiator which will raise the pipe under the floor, which may have some water pooling in it.

kenlmad

jjmcna10 said:

@kenlmad I no do so good in school. Can you rephrase this for a layman?

Sorry for my earlier verbose comment. I was referring to the root cause of the knocking sound (aka water hammer) as others have stated.

If the vent is sucking in and blowing air out (aka panting), that is another sign that there is accumulating condensate somewhere in the supply pipe. In Dan H's steam books, one of the solutions to try is to slow down the radiator's venting. Dial that radiators venting level from 8 to some lower value. Slower venting reduces the steam velocity and reduces the rate of condensate water being generated which may allow the water and steam to pass by each in the shared pipe less violently and more quietly.

Fred

Just as an experiment, try sliding a piece of plastic milk carton under each leg and see if the noise stops. It is possible the radiator is expanding as it heats but is stuck to the floor and can't slide as it expands.

EdTheHeaterMan

When the car has a rattle in it, I just turn up the radio and it goes away.
Not the kind of answer you were looking for, I know. But after you have lifted the radiator with some 1/2" wedged under all 4 legs and you have adjusted the air vent from 8 to 6 and the sound does not go away, try saying "Alexa... White noise"... or something like that.

ethicalpaul

jjmcna10 said:

@ethicalpaul It's pitched towards the the pipe coming out of the floor, in other words the side with the adjustable air valve is slightly higher than the side with the connection to the floor

Thanks. How much higher? I see no shim or lift under the vent side, that would make me feel better.

lovely radiator though