Water hammer inside radiator

bherrick71

This forum has come through three times before. I'm hoping it'll help me a fourth time!

I have two radiators at the front of my house that have water hammer inside of them. It's quite loud. It happens for about 20 minutes until the entire radiators are heated. Examples:

https://photos.app.goo.gl/a2imx2ejz6utNsHJ9
https://photos.app.goo.gl/ipjE1qUwzk7cEbjf6

I have checked everything I can possibly check and it's still happening.

• The vents all work properly
  
• The pipes are all pitched correctly as far as I can tell
  
• (I thought this might be the issue, so I lifted the rads with the hammer an inch off the ground while attached to the pipes over the course of 2 days. It did nothing.)
  
• The radiators are all pitched back towards the valve (level-confirmed)
  
• It's not a pressure issue as far as I can tell. Pigtail is clean and it cuts off at 1.5 PSI.
  
• It has always made this noise and we've had the boiler serviced a few times from different companies of note. Whenever I tried to explain the noise, the professionals all shrugged and said "steam heat!"
  

The hammer travels with the steam in the radiator. Starts at the valve, moves towards the vent as it heats up.

My only remaining ideas are:

1. Maybe the radiator is full of crap? Gunk and water? Is this a thing?
   
2. I'm almost 100% certain the sound is NOT in the pipes below these radiators, and I lifted the radiators and the attached pipes in case this was a problem--didn't work. However, the house does have a slight lean. As discussed, I used a level and there's definitely a little pitch. Both horizontal pipes leading to the radiators are short--about 2 feet at most.
   
3. The supply valves are old and busted?
   

I'm flummoxed and out of ideas! I'd love any thoughts to help us get some more sleep.

pedmec

1) Make sure the radiator valves are fully open or/and not broken at the stem.
2) Check the water level in the boiler.
3) Make sure you have good clean water in the boiler.

is this recent?

bherrick71

1) They're fully open (but very old)
2) Water level is correct
3) I think it's clean--we've had the boiler serviced, cleaned, skimmed several times over the past 3 years. The issue has always existed pretty much exactly like this.

EBEBRATT-Ed

You will probably have to disconnect the radiator from the valve and look inside the valve to make sure the composite disk is in place. They sometimes get brittle and break and fall down inside the valve and will let steam in but will slow down water drainage.

How is the water level in the boiler while steaming. It should stay about 1/2 a gauge glass and be steady or move up and down slowly about an inch or so.

Violent bouncing is NG

The other thing you might try is venting the radiators a little slower even if just to test how the water hammer reacts.

bherrick71

I've tried different vent sizes and nothing helps.
Water level is consistent--not bouncing.
It's going to take a heck of a lot of persuasion to open the nut--I'm worried about cracking the pipe. It hasn't been opened in a long long time.

Is my one thought even possible? The 100 year old radiator is full of gunk, trapping water inside, causing hammer?

pedmec

if you have room to get a wrench on you can get the tailpiece nut loose fairly easy. just make sure your going the right way.

how long has it been like this? exactly like what. since boiler was installed?

bherrick71

Had this issue since we moved in 3 years ago. Boiler is in good shape and is 15 years old or so.

pedmec

Might want to post a pic. a full view picture. incorrect near boiler piping can be your issue.

bherrick71

Here's the boiler with the main that supplies the loud ones: https://photos.app.goo.gl/ipjE1qUwzk7cEbjf6

Here's where the get their steam from: https://photos.app.goo.gl/CJ2kTGXcVwmEL73G7

I know it should go to a T and the main on the right gets more steam. However, both mains vent pretty evenly and both sides of the house get warm at about the same time.

This side of the house has 4 boilers--2 on each floor. Only the bottom floor rads make noise.

pedmec

pic of the boiler??

bherrick71

Sorry! Wrong copy and paste.

https://photos.app.goo.gl/JKmXuCPZc9CAMBUp7

pedmec

are these the only two radiators on that line (doubt it)?
are they the last two?

bherrick71

There are 4. The loudest radiator heats up first, then the two silent ones upstairs, then the other loud one.

bherrick71

Could it be the tie rods?

pedmec

I have a concern with the way the two supply's are connected. They shouldn't have branched off of the (1) 2" riser. the should have tied the troublesome 2" line into the header. this will reduce the exit velocity allowing condensate to drop back into the header and down the equalizer. might have too much condensate traveling down the 2" main. Before you go crazy and start taking stuff apart you really want to confirm the radiator valves are good. the odd sequence of which ones are banging is making me want to eliminate the radiator valves before moving on. the near boiler ain't that bad. it's not bad except for what i mentioned. its the details that can get you in trouble.

bherrick71

I totally hear you re: the piping. I own LAOSH and identified it right away. I'll start with the valves.

That being said, this thread here seems very, very similar to what I have going on.

https://forum.heatinghelp.com/discussion/144653/steam-radiator-bags-loudly-when-heating-and-cooling

bherrick71

I actually just took a look at my radiator, and on the loud one, one of those rods rattles a ton when i tap it. It doesn't seem tight or solid at all. Is tightening this as tricky as it seems?

clammy

Are your radiators recessed if so possibly it’s due to zero insulation behind the them and when this happens the radiator may make some noise but the vent on the off cycle will whistle while sucking air in . I ve seen guys install vacuume breakers on the boiler and mains but it did nothing . As other have stated possible the radiator has some crude in it ,or non steam angle valve ,bad pitch ,debrie in riser or in radiator tail piece nipple . Also if your boiler is piped badly usually the last radiator on a main are the ones most effected by production of wet steam being by the time it gets there ,there not to many Btu s left just condensing back to steam . Are your steam mains insulated ? Has your boiler been washed and and wanded removing mud and crude which affect steam production of any boiler . Have you checked the pitch of your run outs to the problem rads? Again don’t discount the effects of cold outside walls especially on recessed rads . Peace and good luck clammy

bherrick71

They are not recessed, mains are insulated, boiler is serviced regularly. Pitch of the run outs is good.

EBEBRATT-Ed

@bherrick71

Sludge or gunk in the radiators is usually not the problem. Not impossible but usually not the issue.

bherrick71

@pedmec just to ensure I'm following, the troublesome one on the left should be coming straight out of the header on the right instead of branching off? So, like this? https://photos.app.goo.gl/9Zu6MhNiKTajrncK6

Now that I think about it, all the problems in my house, including some valves that spit steam, are on this side of the house. I think you're right that this could be the underlying problem, sending really wet steam that way.

Also let's say hypothetically I wanted to get that problem solved. Is that a big fix or a little fix?

EBEBRATT-Ed

Agree with @pedmec those two supply risers should have come off the header individually. Also can't tell from the picture. But is the tee coming off the header a smaller pipe size than the riser coming out of the boiler? It looks like it is which is wrong, but it could be the camera angle.

bherrick71

@EBEBRATT-Ed of course it's smaller

EBEBRATT-Ed

@bherrick71

Unfortunately, that is your answer. You have water coming up the takeoff from the header because it is too small, and the velocity is too high.

The water skips buy the first supply because it doesn't want to make a sharp turn. When it hits the elbow, it has to go up.


Next time you run the boiler listen at that elbow and see if you can hear the water in there. I am suprised it isn't banging in that elbow.

bherrick71

Thanks @EBEBRATT-Ed . Bummer this is configured wrong, but explains my issues. I like to DIY but I think repiping this correctly is outside of my skillset.