Radiator banging

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  #1  
Old 02-13-17, 06:30 AM
L
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Question Radiator banging

Hi,
One radiator in my single pipe steam heating sometimes is making banging noise. The radiator is inside the wall, so I can't do anything with its tilt.
I've lowered boiler pressure (to 0.5psi plus 1psi differential), but no difference. Is there anything else could be done?
Should I try changing the radiator valve to a smaller (i.e. slower) one?
 
  #2  
Old 02-13-17, 09:12 AM
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l,
Your banging is coming from condensate and steam meeting in the same pipe. Changing the vent or lowering the pressure will not solve your problem. Lowering the boiler pressure although was a good thing. Your boiler should never be set for over 2 psi. As far as vents go, they are used to balance the system so all rads heat together.

If your rad is not accessible I would look at your pipes in the basement and make sure they are all pitched the right way, back to the boiler, especially your pipe going to that rad. It only takes one little dip in the pipe to hold that condensate (water) from draining back to the boiler to create a problem. When the fresh steam hits that pocket of water it creates a violent situation inside the pipe like road rage. Not pretty. You find your dip you'll find your problem.

Sometimes when they are running pipe they find a beam that may be a little low and ordinarily wouldn't mean anything until it is just enough to change the pitch of the pipe and holds that dreaded water and prevents it from returning to its rightful place in the boiler with its buddies left all alone to face its dreaded enemy, steam.

Hope this helps a little.
 
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Old 02-13-17, 09:34 AM
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Hi, spott,
Thanks for your input. All you said makes sense. Unfortunately, pipes in my basement are too buried behind sheetrock.
However, I am wondering, if the issue was a wrong slope somewhere, would not it always bang there? In my case, it bangs only sometimes, usually early morning (about an hour before my alarm clock goes off . Could it be related to the time needed for condense to completely drain back, and delaying somehow the next flow of steam would alleviate the problem?
 
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Old 02-13-17, 09:57 AM
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l,
It very well could be from a slow draining pipe which given enough time drains completely or enough to operate properly which means the more the boiler runs because of the colder weather the less time in between cycles it has to drain completely.

Hopefully you now have a starting point and can further investigate this. Although you most likely cannot do anything about this it would be nice to know where the problem lies.
 
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Old 02-13-17, 10:31 AM
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It very well could be from a slow draining pipe which given enough time drains completely or enough to operate properly which means the more the boiler runs because of the colder weather the less time in between cycles it has to drain completely.
If that's the case [I am just trying to think logically], maybe I should increase differential-- then it would it take more time before pressure drops and next heating cycle starts to give water chance to drain?

Lzr
 
  #6  
Old 02-13-17, 11:24 AM
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L,
You can raise the differential but no high than 1.5. That will give you a cutout of 2 psi. One thing about steam pressure and I know it sounds strange but the higher the pressure the slower the steam moves which means the longer it takes to reach and heat the rads which is what your objective is.

Do you by chance turn down your heat at night or have a set back tstat. Could this be happening when your stat runs to catch up after being shut down for long periods.

If this is the case you might want to try leaving it set at one temp to see what happens and I think you will find it will be much more comfortable and the added comfort and quiet running will offset any possible added cost which I think you will find to be minimal, you may incur.
 
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Old 02-13-17, 12:13 PM
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You can raise the differential but no high than 1.5. That will give you a cutout of 2 psi
Hi, spott,
Thank you for good advises and for your time.
I have fixed temp setting. I just realized that I don't know know if my control subtractive or additive, i.e if main set point is for turn on or for turn off. The images in Honewell datasheet are illegible. Here are the pics of mine. Could we determine from this if differential is subtractive or additive?
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Old 02-13-17, 02:40 PM
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Cut out (2 psi)= Cut in(.5) + Differential (1.5). Differential is additive if this is your model number.

PA404A1033.
 
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Old 02-21-17, 04:34 AM
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New to this site. Most 1 pipe steam systems were originally tied to coal boilers so the steam to the system was active all the time; there was no off cycle. Today, the coal boiler has been replaced by a gas or oil boiler and a thermostat which can cycle the boiler on and off. The thermostat, especially if it has a set back option, may be the cause of steam hammer since the piping and radiation both cool down during the shut down period, causing more condensate to be produced than the system on coal was engineered to handle. On coal, the fire was started and never shut off all winter so there was no shutdown period (system cooling) and since the coal boiler produced steam slowly there was no excessive condensate for the piping to handle. One more thing, the steam inlet valve on a 1 pipe steam radiator must remain fully open, never be used to reduce the steam flow, and should be a minimum size of 1-1/4".
 

Last edited by Steamboy; 02-21-17 at 04:41 AM. Reason: address steam radiator inlet valve
 

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