Pipe banging while the last radiator gets hot. Vent or Slope issue?

JohnBeemer

My friends mother has a Columbia Steam boiler in the basement of her 3 floor townhouse and her bedroom radiator on the 2nd floor is the last radiator in the house that gets hot. All the 3rd floor radiator get hot quickly but the boiler has to be on for at least 20 minutes before the bedroom radiator gets hot. The pipe that goes to the bedroom radiator is visible on the first floor(see pics) and you can feel it slowly get hot from the bottom to the top as it bangs loudly and slowly gets into the bedroom radiator.

I've only been able to see one vent on the entire system and all the radiator vents seem to close when they get hot. Most of the vents are #11's.

The pipe that goes to the problem radiator travels from the boiler to the ceiling to the back of the basement. The pipe is up in the ceiling behind the drywall. I'm not sure if this pipe needs a vent somewhere and it's possible that the pipe isn't sloped properly but I can tell unless I cut open the ceiling drywall.

I put my hand on the banging vertical pipe and it goes up on the 1st floor and it felt like there was a metal snake rattling inside the pipe, very strange and I don't know if this is normal.

I drained the boiler and a lot of sediment came out. The LWCO seems to work because it called the auto water feed and filled the boiler to half way up the site glass.

The gauge on the boiler also seems to stay at zero.

I've attached some pictures and I labelled the banging pipe and vent.

Any idea what my first step should be to fix this problem?

Thanks,

JB

gfrbrookline

You most likely have a horizontal pipe that is pitched wrong, guessing the one under the dry wall. Try raising the radiator up using a 2x4 and block putting a 1/4 or 1/2 shim under the radiator legs. It my take more but you want to raise the radiator in increments so nothing breaks.

gfrbrookline

If you don't have a 2x4 you can rock the radiator back and forth and add washers under the feet to raise it up in increments.

JohnBeemer

If it's a slope problem, I understand that this will fix the banging. With that also fix getting heat to the radiator quickly?

Years ago she has a steam boiler tech come over and the guy said she should have another vent on the system on the opposite side of the house. He was suggesting ripping out the system and re-piping everything because he said everything was wrong. She's never had a problem with any radiator on the other side of the house. Is there any benefit to adding a 2nd vent in the basement? Efficiency, lower fuel cost?

Any thoughts?

Raising the radiator 1.5 inches to get it on a 2x4 might be impossible but I'll do my best.

Thanks again,

JB

JohnBeemer

Does the setting on the boiler pressure look correct? Please see pic.

Thanks,

JB

Jamie Hall

Oddly enough, the pressuretrol looks as though it's set correctly. Wonderful! I wouldn't worry about the pressure gauge -- the 0 to 30 psi gauges which the insurance and code folks require aren't much help at the pressures heating systems run.

It's almost impossible to over vent the mains on a one pipe steam system. The radiators, yes. Too fast is almost worse than too slow. But not the mains. Adding vents to mains never hurts -- except in the wallet, so there is a practical limit.

However. Adding main vents won't help either the banging or the slow radiator. That, as @gfrbrookline said, is most likely to be a section of horizontal pipe pitched wrong, so that the condensate can't get out of it easily -- if at all. This will do two things: first, it will bang and sometimes gurgle. Second, the water lying in the pipe will keep the steam from getting by easily, if it can get by at all.

JohnBeemer

Thanks for the info Jamie. I will work on raising the radiator. If that doesn't work, I guess I'll be ripping out drywall.

JB

JohnBeemer

Yesterday, when I turned on the system, the water level was right in the middle of the site glass tube. The system ran for about 1hr and then I shut it down. About 2 hour later I checked the site glass and it was completely filled. I assume the LWCO called the auto water feeder and added a couple of gallons of water to the system.

When the LWCO sends a signal to the Auto water feeder, does the auto water feeder send a predetermined amount of water to the boiler or will the LWCO also send a signal to close the Auto water feeder valve?

It seems that I need to somehow adjust the LWCO so that it doesn't send I signal to the Auto water feeder until the boiler is a little lower (maybe just a quarter inch of water in the site glass).

I also may need to adjust the Auto Water feed to only send 1/2 - 1 gallon of water to the boiler instead of 2 gallons or whatever it normally sends. There's a test button on the LWCO but I'm sure what that does.

Not sure if this is related to water/condensate not draining back to the boiler because of the slope issue.

I guess I'll work on the slope issue first and see if that takes care of the overfilling of the boiler.

I've attached photos of the LWCO and Auto Water feeder.
The feeder is a Uni-Match by McDonnell and Miller.


TIA

JB

gfrbrookline

My LWCO did that as well, solved the problem by choking the water feed way down.

JohnBeemer

So, you adjusted the water feed to only add a small amount of water? Or did you turn the gate valve down on the copper line going to the feeder?

I'm not sure if the feeder has a meter in it that monitors the exact amount of water or if it's a set time.

Thanks,

JB

Jamie Hall

Whether your water feeder can be adjusted to control the amount of feed or the delay depends on which feeder you have. Check the manual for your feeder, which the installer should have left around somewhere...

JohnBeemer

I have a WF2 http://s3.supplyhouse.com/manuals/1286806478314/40390_PROD_FILE.pdf

It looks like the factory set position 3 is where I want to have it so I'll double check that. There was a lot of sediment in the boiler when I flushed it and I'm thinking it could have somehow gunked up the probe for the LWCO. I'm going to clean the water feed strainer and see if I can change the delay of make (DOM) on the LWCO.

Thanks Jamie,

JB

JUGHNE

In reference to the raising of the radiator, the 2X4 ls for the lever for lifting. Just raising about a quarter inch at a time.
Raising the valve end a little may correct the slope.
You still want the rad itself to slope towards the valve.

Fred

It sounds like that radiator run-out may have lost its pitch. You don't want to raise the radiator up enough to put a 2X4 under it. I think @gfrbrookline just meant to use a 2x4 to leverage the radiator up enough to get a shim under it.
Also, check to make sure the pigtail that the gauge and Pressuretrol isn't clogged. If it is clogged, the Pressuretrol can't see the system pressure and may allow the pressure to build enough that condensate can't return to the boiler until it shuts down. That may explain why the LWCO calls for water and then when the boiler shuts down, it is overfilled. It may even contribute to the banging. Condensate may be hold up in the run-out to that radiator, until the boiler shuts down and the condensate can drain. While the 0-30 PSI gauge is of little value, that may also explain why it stays at zero. It simply isn't seeing the pressure because the pigtail is clogged.

tkos115

If it's not the pitch, could it possibly be that the pipe it torqued against the edge of the ceiling/floor where it does through? Meaning.. is the opening that the pipe goes through where it either goes in or comes out tight against the pipe? I say this because when I first moved into my house I had a pipe that was really tight against the opening it comes out of in the floor. When it heated up it would expand and move against that part of the floor and make a loud popping/banging sound. This was caused from the main pipe in the basement pulled too far to the side. After adjusting it the problem went away.

Just a thought, but sounds like it could be a slope issue.

JohnBeemer

That makes sense to use the two-by-four to lift radiator. Hopefully I can raise it a quarter inch and have it lean towards the pipe. I will take off the pigtail and clean it out.

I'm not sure how close the Pressuretrol is to the unit.

What do you guys think of this video?

https://youtu.be/yfVdd9NDn3w


The guy made his own pigtail and added an extra gauge that only goes up to 5 PSI. I could put a tee off the pigtail and at a 5 PSI gauge that will more accurately show me the pressure in the boiler versus the 30 PSI gauge.

Thanks for all the help,

JB

Fred

You probably should not have taken the Pressuretrol apart. There is a free floating pellet that sits in the center of the diaphragm. If you lost that pellet or don't get it centered correctly, the Pressuretrol won't work.

acwagner

@JohnBeemer I recommend running the boiler and watching the water level to see what it does. It's possible the boiler needs to be skimmed. Dirty boiler water can make the water level very erratic to the point it trips the LWCO and autofills.

Fred

acwagner said:

@JohnBeemer I recommend running the boiler and watching the water level to see what it does. It's possible the boiler needs to be skimmed. Dirty boiler water can make the water level very erratic to the point it trips the LWCO and autofills.

The boiler running at a high enough pressure to blow the PRV will also push the water out of the boiler and back into the wet returns. I suspect that is what was happening here but it is always good to do maintenance on the LWCO and the auto water feed. The pigtail should be cleaned every heating season.
That McDonnell Miller #67 LWCO should be taken apart and scraped out at least every couple years so the float doesn't get hung up on the side walls or from crud build up on the floor of the chamber. MM recommends those units be replaced every 10 years. If you take it apart, you will need a gasket set to put it back together so it doesn't leak.

acwagner

@Fred I don't believe the video is of the OP's boiler. It's from 2015.

Fred

acwagner said:

@Fred I don't believe the video is of the OP's boiler. It's from 2015.

Interesting

JohnBeemer

The video it not mine. Sorry if you thought it was mine.

I was just showing it to you guys to see if it's a good idea for me to do something similar. I'm going to remove the pigtail and clean it out.

While I have everything apart, I could add another gauge that is more accurate at lower pressures if you think that's a good idea. I will remove the LWCO and scrape out any sediment I see.

JB

Fred

@JohnBeemer , we alway6s suggest a 0-3 PSI gauge on a steam boiler. It is far more accurate at showing the actual pressure. The 0-30 PSI gauge should also remain on the boiler. It is required by local code but is actually useless. Be sure to order a set of gaskets before you open up the LWCO. Definitely clean out the pigtail. That alone may resolve the issues you are having.

JohnBeemer

Fred, I'll add the 3psi gauge and clean the pigtail over the weekend. I'm hoping I don't need to take the LWCO apart but if I do I'll get all new gaskets.

Thanks,

JB

gfrbrookline

Disregard what I said about turning down the water feed valve on your LWCO, you have a different type and I am not sure how it would react, mine is a mm67 which lets me manipulate the fill rate with a ball valve. I am not sure how that would work on your version.

I think @Fred missed that you have a MM303 not the mm67 in the video. You do not want to take that apart.

JohnBeemer

Thanks gfrbrooklin. I will attempt to remove the pigtail and LWCO. I'll update this thread with my findings along with pics.

JB

JohnBeemer

I removed the pigtail and and cleaned out a little bit of sediment. Water was flowing easily through the pigtail before I cleaned it so I don't think there was anything wrong with the pigtail or pressuretrol.

I also removed the LWCO and cleaned some sediment off the probe. The end of the probe had some sediment that I wiped off.

I put every back together and now the boiler won't start. It's 67 in the house so I set the t-stat to 75 so it calls for heat. I hear the upstairs t-stat click which usually starts the boiler but the boiler will not start. I turned off the boiler and turned it back on and the LWCO resets and everything looks good but the gas or igniter won't turn on or start. It's like the t-stat isn't sending a signal to the boiler.

The end of the LWCO probe has a little piece that seemed very loose and I'm not sure if that's normal. I hooked all the wiring back exactly how it was before I started. I've attached pictures and a little video of the probe. Here's a link to the video.
https://drive.google.com/file/d/16IPCSEhI8WOuCuBjx-3covxtPxA5p3PB/view?usp=sharing


The boiler actually ran before I started but it did over fill the middle of the site gauge so there might have been a different problem with the LWCO before I start but now the boiler won't turn on. I have a MM ps-802-24

Any ideas why the boiler won't start?

JB

JUGHNE

The loose piece on the probe is there to spin and clean the end of the probe as the water moves around...it is normal.

The threads of the probe do now want any teflon pipe dope or tape on it as the threads must make good ground contact to the CI of the boiler.

What lights come on on the LWCO?

JohnBeemer

Before pulling the LWCO I took 1-2 gallons out of the boiler. I did use some Blue Monster Industrial Grade Thread Sealant on the threads when I re-installed the LWCO into the boiler. There looked to be either teflon tape or sealant on the threads when I removed the LWCO.

When I turned on the boiler, the green light came on the LWCO and the red light came on and I believe started flashing. The auto water feeder started and filled up until the water was half way up the site glass and then it stopped and the green light remained on.

The t-stat was set to 75 degrees but the boiler never started.

Could the thread sealant be causing this problem?

JB

gfrbrookline

Is there a reset button on the LWCO?

JohnBeemer

There's a test button on the top. The LWCO I have does not have a manual reset.

Fred

It has to be either a loose wire on the safety system (Pressuretrol or LWCO) or the probe is bad or needs cleaning with a little emery cloth or fine steel wool. It could also be a lack of a good ground between the probe and the boiler block.

JohnBeemer

I will remove the LWCO today and use some steel wool on the probe and clean the sealant off the threads. The wires are definitely tight on the Pressuretrol and LWCO.

If there were a bad ground, wire or probe issue on the LWCO, I would think the LWCO would not call the auto water feeder but the water feeder is called and stops at half way on the site glass.

When I cleaned the sediment off the probe, I could see the white rod underneath. I didn't remove the c-clip at the end nor did I clean that part with steel wool.

The picture I took were before I removed any of the wiring so I know they are correct. Do you know what voltage readings I should be seeing on the white/red/blue wires or on the Pressurertol?

I guess that would be the next step if I still have problems about cleaning the LWCO.

I will post and update later this morning.

Thanks for all the help.

JB

JohnBeemer

Ok, I made a very stupid mistake. I didn't screw the Pressuretrol tension screw in properly. It was basically just sitting in the hole. Sorry for wasting everyone's time on the boiler not starting. I kept focusing on the LWCO and didn't look at the Pressuretrol until Fred mentioned it. I thought the Pressuretrol would only cut off the boiler if the pressure was to high.

The boiler is now kicking on but I'm still getting banging after slightly raising the radiator (see pics). I will attempt to raise it a bit more tomorrow but I might have to cut out the drywall in the basement to verify the proper slope.

I still need to add a 0-3 psi gauge. Any recommendations on gauge make/model? The Pressuretrol is set to .5 psi but I won't really know the PSI in the boiler until I get a gauge that actually works. The current gauge shows zero pressure. The pigtail is clean so I assume the Pressuretrol is able to function properly.

I closed the ball valve after the auto water feeder because the LWCO kept calling for water and the system would overfill. 5 minutes after the LWCO shuts off the system, the condensate comes back to the boiler and it fires up again.

I'm now wondering if the slope issue on that one 2nd floor banging radiator could be slowing the flow of the condensate to the point where the LWCO shuts the system down.


Thanks again for all the help.

JB

Fred

You don't want to slope that radiator any more than you have already. It is probably pitched to much as it is. You don't want to crack a fitting.
How stable is the water line in the boiler when it is running? If it bounces more than about a half inch, the boiler may need to be skimmed. Excessive bounce can cause the call for water. Also, how long are the wet returns (return pipes below the boiler water line)? Have they ever been flushed out? It is possible they are partially clogged and the condensate is slow to return to the boiler. I am very doubtful that that one radiator can cause the boiler water to drop enough to cause a call for water, that quickly. Having said that, a poor pitch of any horizontal pipe on the run out can cause the water hammer you hear.
One final note: The .5PSI the Pressuretrol is set at is the "Cut-In" pressure. That is the pressure that will allow the burner to re-fire. Inside, the Prerssuretrol is a white wheel that I see is set to "1". That is the correct setting, so when the boiler is running, the Pressuretrol should shut the burner down when the system pressure reaches somewhere around 1.5PSI (Cut-in plus differential) and will restart the burner when the system pressure drops to approximately .5PSI.

JohnBeemer

The piece of wood next to the wood that you radiator is sitting on was the piece that the radiator was sitting on before. The new piece of wood probably raised it another 1/4 inch or a little more.

I will measure the return pipes on the floor next to the boiler tomorrow. I think it bounces more than 1/2 inch but I'll double check tomorrow. The wet returns have probably never been flushed out. The flush drain was completely packed with sediment. I had to remove it and use a screw driver to knock the sediment out of the threaded area to get boiler water flow out of the boiler. I replaced it with a ball valve faucet. The water was black and had lots of sediment. I can only imagine the amount of sediment in the wet returns.

I don't see a union or anywhere to attach a hose to flush out the wet returns. There's an open pipe near the back wall that looks like an old return that was replaced with copper. It looked like the copper pipe that was attached to the black pipe was leaking so I put a paper towel under the pipe but I haven't seen any leaks. I think the pipes could use some better insulations. I've attached pics of some of the piping.

Thanks Fred,

JB

Jamie Hall

You mentioned somewhere up there using thread sealant on the LWCO probe. Not, perhaps, the best idea -- that threaded contact is the ground for the probe, and anything preventing metal to metal contact can cause intermittent operation.

On the auto feeder overfilling -- many auto feeders have a delay option; you might look at the manual for yours and see if it does and, if so, check and see what it's set at. A longer delay might avoid the overfill on condensate return problem.

JohnBeemer

I did use pipe sealant but I don't think it's an issue since the lights are working on the MM PS-802-24. It shuts off when the water level is low and it calls the auto water feeder. On page 3 of the manual is states Sparingly, apply pipe sealant to the external
threads (D) of the probe (A). IMPORTANT: Do not use Teflon® tape. Only use
pipe sealant.

https://s3.amazonaws.com/s3.supplyhouse.com/manuals/1351065020791/84800_PROD_FILE.pdf

I'll double check the MM Series WF2 Uni-Match®
Electric Water Feeder tomorrow morning but the factory setting is position 3 which is the longest delay time of 100 seconds.

Thanks Jamie,

JB

gfrbrookline

I reread your original post re pipe banging, does the banging start before the section of pipe on the first floor gets hot? If so the problem is in the basement. Use the longest level you can get your hands on and check the pitch of the pipes and check for sagging/bellied pipes in the basement that lead to this radiator.

JohnBeemer

I will double check today but I believe the banging starts just before the vertical pipe going from the 1st floor to the 2nd floor radiator. I think it starts in the basement ceiling pipe. When I raised the 2nd floor radiator, it should have pulled the vertical pipe up a bit and changed the pitch of the basement ceiling pipes.

I'm more concerned now with the return condensate not getting back to the boiler before the LWCO calls for more water from the auto water feeder. I'm reading up on skimming and flushing out the wet return since I don't think that has every been done. The boiler was installed 12 years ago and I don't think any of the piping around the boiler has ever been replaced.

I greatly appreciate all the replies, help and info on this site. I am learning a lot about how these steam boilers work and how to maintain them. Unfortunately, I don't think this boiler was maintained properly.

I've attached photos of the location and pipes that are banging.

Thanks again,

JB