Banging steam heat - what's next

Nancy Pullen

We've spend the winter trying to stop the banging, but it's still there. Please help!

I live in a 4-story, eight unit condo building in downtown Boston with a 2-pipe steam heat system. There are stacks in the front of both sets of 4 apartments, and a stack in the rear of one set of 4 apartments.

For several years, our heat was quiet - no banging, tinging or hissing. This October, our pipes started banging and shaking so violently that they chewed up the ceiling around one of the vertical stacks. Around the same time that the banging started, there was construction work in one of the 3rd/4th floor units where a radiator was moved to a new location. Also around the same time, we noticed that the steam pipe running along the ceiling of the basement to the bottom of the vertical stack where the work was done had dropped about 2 inches - causing a trough. It is suspected, although not absolutely clear, that these events are related.

Since October, we have put hangars on several steam and condensate pipes to pitch them correctly. We have added T's at low points of 2 steam pipes that could not be pitched correctly so that collecting water would return to condensate pipes. We have replaced a few blocked lines, unblocked the hartford loop, replaced a blocked pigtail, replaced the pressuretrol because the pressure was going too high and not registering correctly), replaced a component of the autofill (becuase it was vibrating), and ensured that all radiators are level and properly vented.

The banging is still there - although not as violent as before - but still louder than any previous years (and loud enough to wake us up). Our replaced autofill is still vibrating although our plumber says it is fine (and has put cardboard between pipes to reduce the chattering). Our boiler fires until the pressure reaches 2psi and shuts down - after which the pressure drops in about 30 seconds to 1 psi and the boiler fires again. It cycles about 5 times in 20 minutes and bangs towards the end of each cycle - seemingly getting louder each time.

We've had several people experienced in steam heat look at our system and say that we've done the right things, but we seem to be running out of ideas. One of the owners wants to switch over to hot water, but I'm afraid that trying to put pressurized water through our 50-year old steam pipes will cause more problems than it solves - not to mention being very expensive.

Can anyone suggest some next steps? Can anyone suggest a REALLY good steam person in Boston?

We'd all appreciate any help you can offer.

ed wallace

steam problem

oil or gas sounds like you have sagging pipes

t. tekushan

hammer

If the main sagged after the removal of the moved radiator, and was reinstalled without releveling first, there might be a problem closer to the moved radiator now that you rehung the main.

Another thought is that the return was inproperly piped and a portion of the dry return is filling with water near the end of the cycle creating the hammer. Be sure to check the operation of the steam traps. If the radiator was moved and repiped a piece of debris could be holding the trap open thereby driving steam into the return, causing hammer in the return. Any source of water-logging due to pipe pitch will cause problems.

What is the water line doing? Is it surging? If wet steam is being generated, it can wind up accumulating in areas with marginal condensate flow. In other words, the replumbing process will put contaminants in the boiler water causing surging and poor quality steam.

You've given me a clue about the water feeder. If it feeds water frequently, it might be a sign that the water is being "held up" in the system. Does the boiler flood after shut down and all the condensate returns?

I'll catch up later with this thread, but one thought: The building management would need to have to have their heads examined to convert to anything else. Especially when this is a problem that most likely has a simple and inexpensive cause that is merely a head-cratcher.

Unknown

Is there steam in the return piping?

Noel

Nancy Pullen

More water noise than before, not sure about flooding

Thanks so much for your thoughts.

We didn't actually try to move the vertical steam stack that dropped two inches back to it's previous position. We thought that trying to shove it back up through 4 floors might cause more problems than it solved. Instead we T'd off the trough that at the bottom of that steam stack in the basement, and sent that to a nearby return line to eliminate standing water.

Unfortunately, the piping near the relocated radiator is now embedded in the newly renovated walls of the owner who moved the radiator. Can you suggest any non-invasive ways to test if the piping was done correctly of if there is debris in it, or will it require opening walls and floors for access? We've checked the vents on all the radiators. The one on teh relocated radiator was hissing and leaking, but I believe thas has been fixed.

There is currently much more noise of running water in the area of that rear stack (the one where the radiator was moved) than ever before. Soon after the cycle starts, it sounds like lots of water is running down a pipe. Is this what you mean when you ask if the water line is surging? If not, how can I tell if the water line is surging?

Also, how can I tell if the boiler floods after all the condensate returns? I know there's a water level indicator on the boiler. Is there something I should watch for there?

Again, thank you for your thoughts and I appreciate any additional suggestions you have.

Mad Dog

You really need a good steam consultant

Try Find a Professional in your zipcode. Don't be discouraged if the fella isn't that close. I've gone all over the tristate area. Find the right guy and he will find the true source of the problem. Good Luck. Mad Dog

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

t. tekushan

T'd off

Interesting. You t'd off the trough at the low point. You effectively put a drip station there. Good. Now several more questions as to how you implemented it.

a) Did you drip off the bottom?

b) Did you intall a steam trap (balance pressure or float and thermostatic) between the new drip and the return?

c) If "yes" to the above questions, and you still have hammer, Did you use a cooling leg (several feet of pipe before the trap, the trap being closer to the return)?


With regard to boiler surging, if the water in the sight glass bounces much more than an inch or so, its probably creating wet steam, sending too much water into the mains.

You can tell if its flooding the boiler if the water all returns a while after shut down and the sight glass level is more than, say, 3/4 of the way to the top of the glass.

Remember that new piping usually involves pipe dope and other impurities. The boiler should be cleaned any time plumbing is done. Weil Mclain and other manufacturers have good cleaning instructions on their sites. W-M suggests cleaning the boiler with TSP. But follow the instructions. You want to fire the boiler to warm the water but NOT LET IT BOIL. Then you drain it and flush it with fresh with fresh make up water. If there's a surface blow off on the boiler which would be above the water line, I prefer to open that and run fresh water into the boiler slowly for a few hours, there by letting the scum at the surface to be driven out.

Let me know.

-Terry

John Shea

a few pictures...

of the recently worked on pipes may be very helpful.

Nancy Pullen

I'll do some observing

Terry and John S.

Thanks for your questions and suggestions. I'll work on getting some pictures posted and finding out the answers to your questions. It's hard to believe I'm saying this, but I hope it gets cold again so that I can have some time to observe the system and answer your questions before the warm weather really sets in.

I know our plumber has used Squik on the boiler a few times - once at the beginning of our troubleshooting efforts and once again recently after some pipe work was done. Is this equivalent to cleaning the boiler with TSP as you describe?

Hopefully, I'll post some additional information in a day or two.

Thanks,
Nancy

Nancy Pullen

Trough T and sight glass status

Terry,

I watched the boiler (Burnham series 5B) and pipes in the basement last night for 20 minutes or so and this is what I observed.

a) Yes, we did drip off the bottom of the steam line on the left rear stack
b) No, we did not install a new vent between the new drip and the return; although I forgot to check all the way down the return pipe to see if there were any other vents.
c) I listened to the banging and watched the pipes themselves and I think I've determined that the left rear stack is not banging any more. There is the sound of water rushing down the pipes, but I think the banging I hear from my apartment is actually travelling along the pipes from a corner on the right front stack (which has had no major work done on it before the banging started; and since the banging started we have ensured radiators are level and properly vented and have also installed a drip off a trogh on - I think - the return pipe).

The sight glass on our boiler is approximately 5 1/2" high. The scum line is about 3 3/4" up the glass. When the boiler is firing, the water varies between 4 1/2" and 5 1/4" up the glass. During the 30 seconds or so between firings as the pressure drops from 2 to 1 psi, the water drops down to about 4" high in the glass. I was not able to observe the level of the water once the boiler is completely cool becuase it fired off again just as I was getting ready to leave this morning.

I'm working on getting my hands on a digital camera so I can send some pictures.

Thanks,
Nancy

t. tekushan

hmmmm.

what you need between the new drip and return is not a vent, but a steam trap. A steam trap doesn't vent to the atmosphere but is in line from the drip to the return. Its purpose is to allow air and water through and to close when live steam hits it. This prevents live steam from entering the return system. If you have connected the drip directly to the return, the live steam will cause no end of trouble all over the system, and in what appears to be the most unlikely areas. The water rushing you hear is NOT normal. This could be a sign that the condensate at another drip area (e.g. the end of the main) is being held back by the live steam pressure introduced by the new (and untrapped) drip.

With steam heat, the symptoms can appear nowhere near the actual cause of the problem.

Be sure there is some sort of trap in that new drip line. If there isn't, I think this will solve the problem.

If there is, then its possible that another trap has failed causing the problem. I know that another trap failure sounds more like coincidence, but it may in fact be related to a piece of goo (technical term) from the plumbing process stuck in it.

Again, confirm the presence of a new steam trap in the new drip, and then confirm the correct operation of the other traps in the system.

As has been noted elsewhere in this thread, a professional who TRULY knows steam heat may have to look at it. I just want you to know what you are looking at and that you are in a position of knowledge before evaluating the suggestions of those brought in to look at the system.

With any luck, there was no trap installed on the new drip (it will be obvious) and the correction of that situation will correct the banging (water hammer) in its entirety.

Nancy Pullen

Steam trap and steam professionals

Terry,

Thanks for your suggestions on the steam trap. I do not believe that we have one off that new drip, so that will be the next thing we look into.

I think our current plumber has reached the limits of his knowledge as we have reached the limits of the heating season. I think we'll need to take this up again in the fall. I agree that we need a professional who TRULY knows steam heat. Unfortunately, they are tough to find. You've been very informative during this whole process. Is it possible you could recommend someone in the Boston area with the skills that we need?

Again, thanks so much for all of your help.

Nancy

ed wallace

steam problem

do not wait till the fall to get work done better to fix now then find out you need to take down system to repipe when its cold out we still have a few weeks before spring arrives in boston area

Nancy Pullen

Atmospheric System - no steam traps?

Terry and Ed,

You both seem to be keeping tabs on this thread - which I really appreciate.

We just talked with our plumber to ask if he installed steam traps off the drips he put in. He told us that ours is an atmospheric 2-pipe system to which steam traps do not apply. Does this sound right to you?

Thanks so much for your input.

Nancy

t. tekushan

dunno

I'm in Cleveland and as such don't know a contractor in the Boston area.

Anyone out there with recommendations?

You might check the link on this site, "find a professional"

t. tekushan

Technically,

if its not a vacuum system, its atmospheric. This has no bearing on your problem. However, other things do. It never occured to me that you might have a system there called "two-pipe with vent." If the radiators have inlet and outlet on the bottom, each with a valve AND vent on the side, the return system will be "wet" meaning its filled with water (below the boilers water level) and serves as the trap. In this case, a steam trap is not necessary at the newly installed drip.

If there are no vents on the radiators, and there are steam traps at the ends of the radiators, this will have a "dry" return, meaning its mostly full of air with water trickling back through it. In this case you NEED a steam trap at the newly intalled drip.

If this was originally a vapor system (ultra low pressure) and the return pipe coming out of the radiator appears to have only an elbow and not a trap-- don't be fooled. Those would be "special" elbows, with a restrictor in it. In this case you will still NEED that steam trap at the drip.

This is why I think a professional really needs to look it over. There are a number of permutations of steam systems. A good steam person may take a look at the system and say,"Oooohh. I Seee..." and find the trouble right away.

Terry