Help! Persistant Radiator Banging

BobG

I have a 2 story Victorian with single-pipe steam radiators.  Over the years I've made many improvements in it, but one thing I have not been able to fix is a second floor radiator that loudly bangs within the radiator itself (not the piping). We have 10 radiators in the house - all but this one have no banging associated with them. At one point to make sure I wasn't getting a build up of water in the

radiator I blocked the back of the radiator with 1 inch blocks to raise

it but it didn't seem to have any effect on the banging.  We do completely open the valve when using the radiator (it isn't always on, since it is in a guest bedroom.)



I disconnected the radiator from the inlet valve and looked inside the radiator.  When I disconnected it I got a very minor trickle of water - perhaps an inch to 1 1/2 inch in a drinking glass.  Using a flashlight, I looked into the radiator and saw rusty looking deposits here and there along the bottom of the radiator, but I can see clearly to the back of the radiator and most of the opening, other than these small deposits, is clear.  There is no obvious blockage in any of the sections at the bottom.  I removed the relief valve on the back of the radiator and looked inside the radiator from that end - all looks clear with no deposits.  The relief valve is working and steam is getting into the radiator when last used. 



Any insights or suggestions would be much appreciated!

Steamhead

Is it water hammer

or expansion and contraction?



Do you hear the noise as the radiator cools down as well as when it heats up?

Jamie Hall

Banging...

particularly if it really is a water haammer, can be misleading.  It is mot impossible that the actual hammer location is somewhere in the piping leading to that radiator, and not the radiator itself -- but that you hear it in the radiator. This is not a weakness in your hearing -- it's just the way the dang things work.   I would check all the piping leading to that radiator to see if there might be a low spot in there somewhere.  It has happened1 



And it might be an expansion or contraction noise, too, although those are usually much less loud and, in my experience, tend to have more of a sharp tick or ring (how's that for a lousy description!).  They can telegraph, too...

Rod

HI Jamie!

Hi Jamie- Good to see you! I hadn't seen any posts from you in a while. Thought you might have been away on a world cruise or something like that!

- Rod

Greg Maxwell

Banging

My guess is that it is banging in the piping, is not the radiator, due to the fact that you raised the rad to prevent the it from holding water. You need to start working backwards on that riser. Were there any changes in the riser to that rad? Hangers possibly? You dont just start getting water hammer for no reason.

ChrisJ

Pictures

Might help if you can post pictures of the specific radiator as well as pictures of the piping going to it.



Have you taken the valve apart to see if its opening completely and not clogged / nastied up?  I have also heard that venting a radiator too fast can cause a build up of condensate which doesn't have time to get back down the pipe.  What vent is on the radiator?

crash2009

Check the valve

I agree with Chris.  The inlet valve is a good place to start.  Open it up and see if it is working right.

nicholas bonham-carter

Improvements

Can you think of one improvement you have made which preceded the water-hammer problem? Could you have put a new air vent on that radiator?

I think that if you are going to check the valve for obstruction, then you will have to open the bonnet; however I do not think the problem is with the valve being blocked.

My guess is that in raising the radiator vent-end, a lateral feed pipe under the floor has become misaligned, and is thus not draining enough for the steam to go through.

What is your steam pressure settings on the pressure control?-nbc

BobG

Could still use advice - more info on radiator banging

Thanks to everyone who replied to this question with good ideas.  Since I originally posted the question, over the summer I moved the radiator out of the bedroom downstairs into the kitchen. I used the same shut-off valve.  The radiator still bangs very loudly when heating and somewhat less when cooling.  The banging occurs once every 5 minutes or so during heating and as much as 10 minutes or more after the furnace has shut down.



My guess is that a joint or joints between the radiator sections is making the noise during expansion and contraction.  Is there anything that can be done about this?  Can the joints be lubricated from the outside?  The noise is quite loud and reverberates, so I really want to fix it if I can.



Thanks in advance!

Rod

Tinks and Bangs

Hi- What make and model vent do you have on this radiator? Have you checked the radiator to see that there is a bit of slope so the condensate will drain out the steam pipe? Have you checked the radiator to see whether there is a bow in the bottom that would collect condensate?  "Tinks" are pipe metal expanding , "bangs" are steam collapsing.

- Rod

BobG

Help! Persistant Radiator Banging

When we first posted this problem back in August, a number of replies were sent on things to look for or consider. Thank you all for that.  I was fairly certain that the problem was in the radiator and not the piping, but decided to move the radiator from an upstairs bedroom down to the 1st floor kitchen.  No small task since the radiator weighs (at least) 200 and 300 pounds, but I got some help.  I made sure that the radiator pitches toward the inlet valve so condensation drains out, and there is no sagging that would cause condensation to collect in the radiator.  With the start of the heating season, we find the radiator is still making the loud banging. Though still disturbing, at least the noise isn't waking someone up in the middle of the night!  I did use the same shut off on the inlet to the radiator (it is 1-1/4"

pipe size), but it looks clear of anything that would cause steam or condensation to get

trapped.  I also tried several different relief valves (which I

switched from other radiators), but it made no difference.



One question that was raised by you guys was whether the noise was possibly expansion and contraction.  Originally I assumed it was caused by steam trapped because it was so loud and sharp, but now I have noticed that the banging occurs both during the heating up and cooling down of the radiator (as much as 5 to 10 minutes or more after the boiler has shut down).  The noise is not as loud when the radiator is cooling down, but still fairly loud.  This radiator is similar to most of the radiators in the house, though some have more sections and some less (all or most are probably original to the house, which is 100 years old).  This one has 9 sections and is about 38" high x 22" long x 7-1/4" wide.  Each section is cast with two vertical "chambers" connected at the bottom and the top.  The sections are held together at the top by a threaded bolt that runs horizontally down the center of the radiator, and they are butted together at the bottom by what look like flanges.  I noticed that at the bottom between 3 of the sections, there is a small gap of about 1/64th" that I can see through with a flashlight to what appears to be an interior pipe that runs along the bottom inside the radiator.  I do not see gaps like this in any of our other radiators.  Is it likely/possible that the noise is occurring at these flanges as a result of expansion and contraction?  And if so, is there anything that can be done - such as lubricating the flanges from outside the radiator? If yes, what would you suggest I use to lubricate.  Or, is it more likely that the noise is occurring at the top of the radiator, where the sections have small "feet" that are butted together and (as mentioned above) are held by a threaded bolt that runs horizontally down the center of the radiator?.  If so, how might I correct that?  Once again, thanks for taking the time to read this, and any advice you can offer would be appreciated.  Bob

nicholas bonham-carter

mysterious banging in radiator

you could now try to tighten up the nuts on the rods which hold the sections together [1/8  turn at a time] to see if this makes any difference. it would be good to put some lubricant on the threads before making the first turn.--nbc

BobG

Help! Persistant Radiator Banging

Nicolas, Thanks for your suggestion about tightening the rods.  I am attaching some pictures of the radiator.  The only rod that I see is near the top of the radiator with 11/16" hex heads on each end (as shown in pictures 4 and 5).  Picture 6 shows the "feet" at the top of the radiator between the sections.  I find all of these are (or seem to be) tight together.



It is not clear to me how (if at all) to tighten the bottom of the radiator.  Picture 7 shows an 1-1/2" hex head at the bottom right end of the radiator.  Picture 8 shows the inlet valve, union, nipple and 1-1/2" female threaded octagon (that the nipple connects to) at the bottom left end of the radiator.  Picture 9 shows one of the gaps between what I am calling flanges between the sections, and picture 10 shows the tip of a nail file inserted into the gap.  As indicated in my last post, this is the only radiator in the house that I see these gaps (3 of the 9 sections have gaps of about 1/64th"), which causes me to suspect that this may be related to the banging.  Any suggestion on how to tighten the bottom of the sections?



Thanks, Bob   (hope the pictures come through - I am not used to doing this) 

Alan Welch

Picture #8

If that is a 1" riser feeding a 9 section radiator, it could be the problem.  Was it also connected  1"  before you moved it ?

Steamhead

You can't

This is a Rococo, made by American Radiator Co. The bottoms of the sections are held together by nipples with right and left hand threads. Those gaps are not a problem as long as they don't leak.



At this point it might be well to take the radiator outside and flush it out. It might be full of sludge.

BobG

Help! Persistant Radiator Banging

Steamhead, OK, so I cannot tighten the bottom of the radiator.  There are no leaks (neither steam nor condensate escaping) where the gaps are at the bottom of the radiator.  I assume there is no way to (or no point in trying to) lubricate the interior connections of the radiator? 



As indicated in the original posting, when I removed the inlet valve back in August (before this heating season), I had a very minor amount of water come out (about 1" in a drinking glass).  I looked into the radiator with a flashlight and could see all the way to the back of the radiator, and it was clear - other the small deposits hear and there along the bottom of the pipe going down the radiator.  I saw no blockages, and there was no sludge.



Thanks, Bob

BobG

Help! Persistant Radiator Banging

Alan, No the radiator was originally connected to an inlet pipe that was the same size as the valve.  I switched the radiators from an upstairs bedroom and the downstairs kitchen.  The one in the upstairs bedroom (9 sections) was banging, and still is.  The one that was in the kitchen (5 sections) did not bang, and still does not now that it is in the 2nd floor bedroom.



The fact that the banging occurs during the heating up and cooling down of the radiator leads me to conclude that the noise is occurring during expansion and contraction.  The noise is louder during heating, but still pretty loud when cooling down (and as much as 5 to 10 minutes or more after the boiler has shut down).



Thanks, Bob