steam radiator bags loudly when heating and cooling

bang

We have a 100 year old home with a dozen one pipe steam radiators of varying sizes, and all but one have no problems.  One radiator bangs very loudly at least once or more when it is heating up, and often once when cooling down (as much as 10 minutes or more after the boiler has shut down).  The radiator is pitched sufficiently back toward the inlet valve, so flow of condensate does not seem to be an issue.  The radiator heats completely and in the same amount of time as other radiators in the house, so there does not seem to be any problem with air venting and steam getting into the radiator.  The radiator has 9 sections interconnected along the bottom.  It is 37-1/2 inches high,  21 inches long and about 8 inches across (several of our radiators are the same size as this).  The fact that it bangs loudly both when heating up and cooling down suggests to me that it is caused by expansion and contraction of metal against metal inside the radiator where the sections interconnect along the bottom.



Can anything be done to correct this?

Rod

Radiator Problems

Hi- It sounds as though the steam and condensate aren't getting along. When you say that the radiator is "pitched sufficiently" it is possible that it could be pitched too much. You just need enough pitch to "encourage" the condensate to flow out of the radiator. Too much pitch causes the water to "pool" at the inlet and this interferes with steam entering the radiator. 

The inlet steam valve must be fully open otherwise steam and condensate collide in the narrow partial opening. It maybe that because of age, the valve is malfunctioning and not fully opening.

Vent - What make and model vent are you using on this radiator? You might try a slower vent as this would slow down the condensing a bit. Slower condensing means less volume of water accumulating which may allow the steam and condensate to get along better.

- Rod

Sil

valve

is the valve fully opened?

Jamie Hall

Expansion

can indeed create quite a bang -- often several, but not at all uncommonly just one when heating and one when cooling.



The trick is to figure out what is sticking to make the bang.  One possibility is that the feet are sticking on the flooring; being a relatively simple fix it's worth exploring: try putting a square of a plastic milk bottle or similar semirigid, moderately thick, piece of plastic under each foot.  It can't hurt, and it just might help.



Another possibility is that the riser or runout is hanging up on something; look them over carefully and see if they are in hard contact with the floor or framing at some point.



It really doesn't sound like a water hammer problem to me, given the timings.

bang

banging radiator

Jamie,  Thanks for you reply, I did try putting plastic furniture discs under the 4 feet of the radiator, but it stills bangs.  The inlet riser is not against the floor, so not causing the bang.  The problem is with the radiator itself.  This radiator was in one of our bedrooms, but I moved it to the kitchen because I definitely did not want the noise to wake someone (it is a loud metallic sounding bang).



There are 9 sections to this radiator connected along the bottom.  The sections are like elongated donuts (35" high x 7" wide).  A threaded rod runs along the inside of the sections near the top of the radiator, which holds the top of the sections together - compressing together small "feet" that extend out from each section.  There must be some kind of a sleeve between each section at the bottom to allow steam to pass.  Some of the sections butt completely to each other at the bottom, and some have a small gap.  I tried spraying some lubricant on the seams between the sections at the bottom (both the ones that butt together and the ones that had small gaps) and I did the same to the small "feet" at the top of the sections.  My thinking here was that metal might be binding against metal, since that is what it sounds like.



How are the sections internally connected at the bottom (so steam can move through the radiator but not escape between the seams)?  Is it possible that the banging is occurring at one or more internal connections?  If so, is there anything that can be done to correct that?  Another thought is the rod that runs through the center near the top.  Could that be too tight - causing the small feet to bind against each other?



Thanks, Bob

Jamie Hall

It can be tricky...

In answer to the simple question -- between the sections at the bottom there is a short nipple which is tapered at each end to fit into a similarly tapered opening in the radiator section on each side.  In most, but not all, steam radiators there are similar openings and nipples at the top.



In most cases there is (are) a tension rod at the top and another one at the bottom -- which you don't mention.  The tension rods should be tight -- but not very tight.  One has to be rather careful with them, as it isn't hard to strip the threads or even break the rod.



If there is no rod at the bottom, there must be some other way to hold the sections together.  Is it possible you could take photos of the ends of the radiator, so we could see what kind of arrangement there might be?

bang

steam radiator bags loudly when heating and cooling

Jamie,  Thanks for the response.  I am attaching a number of photos of the radiator.  As I hope you will see, the only rod is located near the top of the radiator and has a hex-head on each end.  I am not sure how the bottom is held, but you will see a large hex-head on the bottom on one end, and the other end has the inlet pipe attached.  Most of the radiators in the house are similar to this one.

rcrit

shorter level

If you have a shorter level (like an 8") you might want to give that a shot. Sometimes radiators sag in the middle (I know mine do).

bang

steam radiator bags loudly when heating and cooling

I did check for sag, but used a level that crossed the entire top of the radiator and looked for gaps between the bottom of the level and the top of the radiator sections.  The level was in contact with the top of section3, 6, 7, 8, and 9.  A small gap (about 1/64" to 1/32") showed between the level and the tops of sections 1, 2, 4 and 5.  The biggest gap was at section 1, which is connected to the inlet piping.



It does not seem that this amount of sag would result in any blockage.  Have you found this to cause banging?  And if so, were you able to do anything to realign the sections and stop the banging?



Thanks, Bob

bang

steam radiator bags loudly when heating and cooling

Yes, the valve is fully open.  We leave it open.



Thanks

bang

steam radiator bags loudly when heating and cooling

I too originally thought this was a conflict between condensate and steam, but when I realized that the bang was also occurring long after the boiler had shut off and the radiator was cooling down, I concluded that the issue was expansion and contraction not a steam bang.



I also do not believe the problem is with the valve because of the fact that the banging only occurs once or twice during heating and perhaps once during cooling as much as 10 minutes or more after the boiler has shut off.



This radiator is very similar to most of the radiators in the house, and it heats up at about the same rate as the others.  I have tried switching some of the vents between the other radiators and this one and adjusting the vent rate, but that has had no effect.



Thanks, Bob

bang

steam radiator bags loudly when heating and cooling

Jamie,  In your last message, you asked if I could send some photos of the radiator.  I did send those on 1/21, but have not heard anything further since then.  I am guessing that things have gotten very busy for you, but I would appreciate hearing from you when you can.  No one else seems to be familiar with the banging problem that occurs during heating up and cooling down of a radiator.



Thanks, Bob

Alan Welch

Pipe diameter of riser

Was this radiator replaced ?  Usually the radiator valve does not have a reducing bushing in it.   I think the supply pipe might be undersized for the radiator, let's see what others think.  Any of the other radiators  piped   the same?

bang

steam radiator bags loudly when heating and cooling

Alan, Thanks for your reply.  This is the only radiator with a reducer on the inlet piping, but that is because over last summer I switched this radiator from one of our 2nd floor bedrooms to the kitchen because of the banging (I didn't want to wake someone sleeping in the bedroom).  The inlet piping in the bedroom is larger than the inlet piping kitchen, but the banging only occurs in this radiator.  Also, I would think the issue with undersized piping would be steam in conflict with condensation returning to the boiler.  Correct?   I found that the banging occurs both during heating up and cooling down of the radiator, and as much as 10 minutes or more after the boiler has shut down.  That suggests to me that it is related to expansion and contraction of the radiator itself.



Thanks, Bob  

Charlie from wmass

Try a new vent

The supply is too small but that would make noise during heat cycle not cooling. Gaps are not and issue if they are not leaking. Nothing moves against anything in a radiator, all parts expand and contract together. Make sure the supply pipe is not binding under the floor and put slides under all four feet not just 2.

bang

steam radiator bags loudly when heating and cooling

Charlie, Thanks for your reply. A while ago I did put slides under all 4 feet, and did try different vents in the radiator (switching from other radiators), but these steps did not help.  The radiator in question bangs loudly at least once when heating up, sometimes two or three times, and often once when cooling down - and as much as 10 minutes or more after the boiler has shut off.



I have checked to make sure that the pipe feeding the radiator is not binding on the floor, etc., but since this radiator banged when it was in the 2nd floor bedroom and now still bangs since I moved it to the kitchen (and the radiator that was in the kitchen is now in the bedroom and doesn't bang), I don't think the problem is with the inlet piping.  The bangs seem to come from the radiator itself.



This radiator heats up at about the same rate as other radiators in the house, and on colder days all 9 sections of the radiator do get hot.  So, that suggests to me there is no blockage in the radiator.   I am at a loss as to what is causing the loud bangs, and what could be done to prevent them.



Thanks, Bob

Dave in QCA

I Had a Noisy One Too!

I had a radiator that through the course of the heating cycle, both heating up and cooling down, would let out a couple real loud bangs.  There were also some very soft "tic tic tic" sounds when steam was coming into the first 3-4 columns.  I could tell that none of these sounds were water hammer.  I know this will raise questions from the skeptics...   but I just could tell.



From the advice obtained on here, I cut out little square pieces plastic from a milk jug and put on under each radiator foot.  This helped alot, but did not completely solve the problem. So, I used some spray PTFE type lock lubricant and applied it to the knuckles at the top of the sections, where they are pressed together.  (This is a steam only type radiator"   After the first application, it was much improved.  I have applied lubricant two more times and at this point I am happy to report that the radiator is completely silent!!  And, we have a happy tenant too!

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steam radiator bags loudly when heating and cooling

Dave,  Thanks for sharing what you have done.  I do not have the same lubricant you mentioned, but after reading your note I tried some WD-40 on the knuckles.  It seems like that caused the radiator to bang several more times than it had been banging, but if that is true (and not my imagination) at least it may mean I am dealing with the source of the bangs.  I am going to try applying WD-40 several more times and see if that helps.  Is the lubricant you mentioned a better one?  The knuckles seem tightly compressed against one another.  Is there any possibility that they are too compressed?  There is a threaded rod through the top of the radiator that holds the top of the radiator together.  I am wondering if I should try loosening that a turn or so?  One of the other responders said this should be tight but not too tight, and cautioned that trying to loosen it could result in damaging the threads.



Thanks, Bob

MTC

Worst case scenario,

if you try to loosen up that rod and damage it, you can go buy a 3 foot piece of all-thread and a couple nuts from home cheapo or wherever, and cut a new one to size and install it.



I've taken them apart a few times and never had trouble, where you're most likely to have problems is in trying to tighten them up too much.

bang

Thanks everyone for your help

I just wanted to post a final note of thanks to everyone who offered suggestions, and let you know that the banging has been stopped and how. The noise was occurring at the knuckles at the top of the radiator where the sections are held together by a threaded rod that runs through the center of the radiator. Initially it was not obvious that this was where the noise was coming from, but after receiving one suggestion I tried applying WD40 to the knuckles. This actually caused the banging to occur more frequently, but at least I knew I had located the source of the noise. My next step was to loosen the threaded rod several turns and gradually. That was it - the noise is stopped. Thanks again, Bob

Dave in QCA

Sweet Success!

I'm so glad you solved the problem!   And thank you for sharing the details of what you did to resolve the problem. 

RJ_4

banging

the radiator valve looks pretty old, I would take the bonnet loose and see if the disc has broken down and is partially blocking steam/condensate

remebero

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I am looking to buy this CROWN BOILER CO Water Heater from them

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