1 radiator banging time to replace?

y2kc0wb0y

1 pipe system with 6 steam radiators in 1920's era row house (Washington DC). System is quiet sans one large radiator. The upstairs radiator has a consistent bang when it comes online. 5 progressively louder bangs and then it stops. I made sure there is good tilt on the problem radiator to ensure drainage and it heats evenly with the rest of the house. Valve is all the way open. Seems to me given the length of the radiator (long as two windows) it could have a low spot in it. I've tried adding more tilt but that has not helped.

Curious if I'm missing anything in my troubleshooting? Could it be the valve?

ethicalpaul

You can't fix radiator banging by replacing it. I would bet a lot of money that the piping going to that radiator has settled and there is water collecting in it. There are two places where it might be and with careful listening you might be able to find it. It might be just below the radiator in a short horizontal section that is typically in the floor, or it might be in a similar horizontal section that might be coming off the main in the basement.

You _might_ get lucky and be able to carefully raise the radiator very slowly over several days to see if anything changes. By raising the radiator, you can undo the possible change in pipe angles that may have resulted from likely settling of the house over the last 100 years.

You mentioned the valve and it could be that the valve has failed in a way that is trapping water in the radiator. You might be able to get an idea of this again with careful listening right at the valve (a screwdriver makes a great stethoscope, just put the sharp end against the valve and the handle against your ear). See if you hear gurgling at the start of the heating cycle but don't deafen yourself when it bangs!

CantabHeat

Concur with the above. New rad is very unlikely to fix the banging.

As described above have seen simply raising the radiator slightly fix the issue which appeared to be water stuck in a pipe that had settled and lost its original pitch. It’s actually amazing what a few strategically placed quarters under a radiator can do to deal with issues! Money well spent.

After the banging subsides listen closely for gargling or bubbling/sloshing sounds which may guide you to where water is building up.

y2kc0wb0y

I will listen with screwdriver per advice. Can confirm there appears to be a short section of pipe from riser in the wall to radiator via the floor. I do not recall gurgling here but haven't listened with a screwdriver. Thanks - I'll reply back with my findings.

Jamie Hall

There is another possibility in a large radiator. Expansion. If the banging happens as the radiator is heating up, that may be it. If so, try placing something slippery -- I've had good luck with squares cut from plastic milk jugs -- under the feet and see if that helps.

If the banging is before the radiator itself starts to get warm, then it's likely water hammer in a pipe.

y2kc0wb0y

Shimmed the long radiator up ($1 in the front $1.50) in the rear after listening to some gurgle. FIXED! Turns out you were right! Upon inspect you can see where the wood floor was bowed/eaten over the years by the weight/movement of the radiator. It was subtle but it was. House is warm and quiet now.

I've been poking around on this forum for years and with all my research never once did read about lifting the whole radiator to solve a banging issue. The other sad/funny thing is I've had some very reputable pros here that never mentioned it either.

You win the Internet today.

ethicalpaul

Great! Just passing along some knowledge kindly given to me by the great folks here 😀

Mine unfortunately wasn’t able to be fixed so easily, see the Autumn Saturday Repipe thread 😅

clammy

If thy didn’t raise the radiator and suggested to replace the radiator to stop banging please do not hesitate to show them the door .i have been to a few where the previous contractor talked them into replacing radiator due to banging they replaced still banged there answer is well that’s the way steam works bull ,there’s always a list of things to chk first off pitch ,supply valve pipe size and riser size in relation to radiator edr and venting . It s great u fixed it yourself there’s always cause and effect and the fix is usually not to difficult in some cases .peace and good luck clammy

mikeg2015

I’ve raised all of mine for this reason. Even if it wasn’t hammering, it would impact balance since Vapor prefers to rise not flow laterally or downhill.

tkos115

mikeg2015 said:

I’ve raised all of mine for this reason. Even if it wasn’t hammering, it would impact balance since Vapor prefers to rise not flow laterally or downhill.

I did this with my big one in the kitchen and it helped it heat up faster. It wasn't banging or causing any issues but I could tell it was settled into the floor a bit.

y2kc0wb0y

Following up. I ended up raising most of the radiators in the house because I noticed the 94 year old floors have stressed under the radiator weight (banging or not). House is mostly quiet, as I mentioned before, but I now have a new rhythmic tick in one of the downstairs radiators. Sounds like its coming from the middle of the radiator. Faint but a tick/drip. I might need to lift this one more? Expansion?

Jamie Hall

Sounds like expansion noise. Very hard to get rid of... it might help to put something slippery (like pieces from a milk just) under the feet. Then again... it might not.

Hap_Hazzard

I've put polished marble slabs under two of my radiators so they'd have a smooth, hard surface to sit on. You can find marble thresholds in the tile section in your home improvement stores. If you have room to fit it in or you can replace the worn out piece of flooring with it, it makes a nice upgrade.

Shalom

Jamie Hall said:

something slippery (like pieces from a milk just) under the feet.

Sometimes also helps to shove it down the floor next to the pipe.

y2kc0wb0y

^

Hap_Hazzard said:

I've put polished marble slabs under two of my radiators so they'd have a smooth, hard surface to sit on. You can find marble thresholds in the tile section in your home improvement stores. If you have room to fit it in or you can replace the worn out piece of flooring with it, it makes a nice upgrade.

"Marble" that's clever idea. I can probably find 2x2 block samples to accomplish this.

Shalom said:

Jamie Hall said:

something slippery (like pieces from a milk just) under the feet.

Sometimes also helps to shove it down the floor next to the pipe.

Thanks! Cannot remember the last time I purchase a gallon of milk. Maybe neighbor drinks it and seeing we all share a common trash day......

mattmia2

Lots of other slippery plastic containers, especially some deli containers and clamshell packaging.

Hap_Hazzard

Half-gallon containers work just as well!