Steam heating, clanking noise?

Cordcutter77

New poster here, hello!

I've been combing through this forum and I see that lots of folks' steam/water hammer issues are all quite unique, depending on type of system, age of system, 1 or 2 pipe, etc etc. though the sounds are similar; which leads me to believe that steam heating systems are complex and need a lot of investigation, isolation and different remedies in hopes to find the root cause of the problem.

Been grappling with clanking noise since early Jan this year (2024), culminating from apartments below me.

Have 2 radiators (look like the image attached), with circular supply valve handle (open/close) and a vent/air valve.

Live in a 656 sq ft open studio (pre-war brick facade building) which happens to have 2 radiators; 1 6ft long and 1 2 ft long. Always have to keep the 6ft long one in Open valve because several years ago the pipes froze because I had it Closed [that took several hours of using a hot-shot pipe thawing machine to get the pipes thawed]. The 2 ft radiator I keep in Close valve because the apartment is at 82F (even with windows open about 1/2 inch) just with the 6ft long radiator needing to be in Open.

That said, the clanking noise is an issue. The clanking improves slightly though temporarily if I turn the supply valve to Open. I can hear the water running up to the radiator when I turn the supply valve to Open. The clanking stops, only just for a few minutes, but then comes back. Closing the supply valve makes the clanking louder.

It seems that with this radiator whether the supply valve is Open or Closed the clanking occurs; and it clanks for hours, until the heating system turns off from the main heating system.

To be honest, the 2 ft long radiator is not needed to be in use at all. The 6 ft long radiator keeps the apartment at a balmy 82F [86F with the windows closed].

I've asked if the 2 ft long radiator could be capped so it's shut off completely, and was told, NO. Their reason was that cutting it off would cut off all the heating supply on all radiators in that vertical line. Is that true?

I was also told that the system is bled every 3 days. Does it need to be done that often? Isn't that a signal that there's another issue that isn't getting addressed?

It'd be great to have expert advice here on where the root cause of the problem is, and what specific steps need to be taken to resolve this because it's only Jan 29 and we still have another 2 months of cold weather to get through [I live in NYC by the way].

Thank you all so much!

Jamie Hall

As to turning off that convector. Turning it off won't hurt anyone else. Don't worry about that. It may not, however, solve the clanking. Leave the valve either all the way open or all the way closed, however. Not in between.

Two other ways to reduce the heat. One would be to change the vent to a slower one. The other is really simple: that type of convector radiator depends on... convection to heat. So, stop the convection. A simple way to do that would be to place aluminium foil on top of the fins and put the front back. If there's still more heat than needed, cover part of the long one as well.

The clanking is most likely water getting trapped somewhere. Where is a very good question. It could be in a convector with the valve part way open. It is at least as likely to be in a bit of horizontal piping which is pitched the wrong way -- and since this is not all your own to play with, that could be really hard to find and fix.

Big Ed_4

The water you hear is the condensate that was trapped in the convector, running back to the boiler . They don't fully shut off the steam , some steam will pass. To leave open for the freezing problem but to turn down the heat . Cover the convector with tin foil to shut off the convection which is heating the room.

Cordcutter77

Jamie Hall said:

As to turning off that convector. Turning it off won't hurt anyone else. Don't worry about that. It may not, however, solve the clanking.

So capping it may not solve the problem, but doing so won't affect the other radiators. Good to know!

Jamie Hall said:

Two other ways to reduce the heat. One would be to change the vent to a slower one.

I suppose that if the 6 ft radiator needs to stay Open, then changing the vent to a slower one could help a bit in lowering the temp in here from a balmy 82F.

Jamie Hall said:

The clanking is most likely water getting trapped somewhere. Where is a very good question. It could be in a convector with the valve part way open. It is at least as likely to be in a bit of horizontal piping which is pitched the wrong way -- and since this is not all your own to play with, that could be really hard to find and fix.

And THIS is why it's such a mystery to find the root cause!