Need Help silencing hammer at Return

Stephanie

I am a very frustrated homeowner- not a professional. I recently had the return plumbing to my steam boiler replaced. It had rusted to the point that it crumbled when removed. Since the repair I have LOUD banging at the horizontal pipe that returns to the boiler. It ran quietly last season. I had another plumber/heat pro come in to help. He removed water off the boiler to flush sediment out of the system. I have since done this myself- 10 gallons worth. I also flushed the low return that runs along the basement floor. The water while still rust colored is much clearer. The plumber would like to come back in to change the configuration of some of the pipes. I'm afraid of opening another can of worms. Now I am also noticing that the Automatic Fill is topping off the boiler at the end of each cycle...

1- What can be done to stop the noise?

2- I'm now thinking I may have a leak in the boiler itself. Can these be repaired?

Thanks for listening.

nicholas bonham-carter

hammering return

was the boiler cleaned after the re-piping? oily water can cause unstable waterline behavior, and hammering.

can you feel the location of the hammering by putting a gloved hand on the pipes? what appears to be your hartford loop has a longer horizontal pipe than is recommended

can you close the inlet valve from the auto filler into the boiler? mark the water level on the sight-glass rod with a clothespin, and watch for a change in level for the next few days.

if there is a leak, then you need to find out whether it is the boiler, or more piping in the return. over-filling the boiler above the top will cause any holes to weep into the firebox.--nbc

also have the plumber put a pipe going down to the floor on the pressure relief valve before someone gets scalded. is there a gauge on the boiler?

Rod

Need More Info

Hi Stephanie-  The cause of your noise problems is the improper configuration of the piping attached to your boiler. (see attached photo)  I can see other things that need to be corrected. Look on your boiler -there should be a placard which tells the make and model of the boiler. Let us know what they are. I also suspect that you have other problems withe the piping . Can you post more pictures of your boiler taken from different sides and from farther back so we can see both the boiler and piping that is connected to it. This allows us to trace out the piping and how it is connected.  We can zoom in if we need more detail.

There are some very good books on residential steam heating in the Shop section of this website. The best one to start with is "We Got Steam Heat!"

http://www.heatinghelp.com/products/Steam-Heating-Books/25/61/We-Got-Steam-Heat-A-Homeowners-Guide-to-Peaceful-Coexistence

It's written for the homeowner new to steam heating. It's easy humorous reading and in an evening or two will put your knowledge of steam heating light years ahead. This book will pay for itself many times over.

 Here is a link to a video about near boiler piping configuration that may be of help to you:

http://www.heatinghelp.com/article/107/Steam-Heating/118/Steam-boiler-near-boiler-piping

Also what type of steam system do you have?  This is determined by the number of pipes  connected to each of your radiators. (1pipe connected = a 1 pipe system , 2pipes = a 2 pipe system.)

Why do you think you have a boiler leak?

Let us know some more about your system and then we can take it from there.

- Rod

Stephanie

Re: Need More Info

I have done some research to learn more about steam heat. The pipes around my boiler look nothing like the diagrams I've seen! What confuses me is that about 50% of the time the system will run quietly...

To answer some of the questions-

Rod- I have a 1 pipe system. I think I may have a boiler leak, because I hear some hiss and the auto-fill has activated after the last few cycles.

nbc- Clean water was run into the boiler after the plumbing repair. In addition rusty water was drained out of the system twice over the past 2 weeks (about 10 gal each time). The hammering seems to be coming from the horizontal pipe. Not quite a Hartford loop given it is above the water line and too long. Does't seem to qualify as a Gifford loop either.

I have included some more pictures including a close-up of the repair. The boiler is a Weil McLain.

Rod

Boiler Piping

It needs to be piped as in the installation diagram. You didn't state the model number but it looks like an Weil EG so I 've attached the I&O manual for that boiler. (See page 14 for boiler piping configuration)

Since you already know some steam terminology that's a great help! Notice in the installation drawings that a close nipple and elbow is used to connect the return piping to the Equalizer. This is to stop the return water building up velocity (which it does using a long straight pipe.)  On your present return with the long straight pipe, the cold return water meets the steam in the equalizer and the steam collapses (condenses) causing a vacuum. Cold water in the long return pipe rushes into the vacuum void and in doing so collides with the wall of the tee connecting it with the equalizer. The steam collapse and collision results in the noise you hear.  If piped per the installation manual, the cold water enters the equalizer pipe below the boiler's waterline and mixes with the hot boiler water which makes it less likely to cause the steam in the equalizer to collapse.



Leak- It may not be a leak but rather the slow return of condensate from the system to the boiler. If the boiler water drops to too low a water level, the automatic water feeder will come on and add more water to the boiler. The indication of having a slow water return is that when you shut the system off and give all the water a chance to return to the boiler the boiler water level will end up higher than normal. Slow return of water to the boiler may mean that your wet return piping is partially clogged and needs to be cleaned out.

Boiler pressure- What is the maximum pressure  your systems operates? Your system should be operating at under a maximum 2 PSI. otherwise a lot of water may be carried up into the system piping.

- Rod

Stephanie

Re: Boiler piping

Rod- Thanks for the manual. I will look over the diagram as you suggested and share with my plumber. Re-piping the boiler while probably the best route sounds like an expen$ive solution.

I have been in this house for 4 years and have had my fair share of un-"Rube Goldberg"ing situations. For the heating, I have had the radiators sandblasted and powdercoated. New valves were used when they were reinstalled. I swapped the locations of some to better distribute heat. Last year the boiler required a new ignitor and burners. I still need to add insulation to the pipes in the basement...

The hammer I have described has developed after the repair to the return piping this year. While certainly not to the manufacturer's specs, is there any possiblity that the horizontal pipe originally may have had a slight upward or downward pitch that may have reduced the chance of hammer? I'm thinking that an extra thread turn or two could have changed things ever so slightly...this system used to work.

Leak- There sometimes does seem to be a slow return of condensate from the system to the boiler. I'm trying to see if this has some relation to the hammer. My call to my plumber/heating pro was do to the low water cut-off coming on mid-cycle, shutting the boiler, and then re-igniting without filling. That situation seems to have resolved with the flushing of the system. (I flushed some water through the wet return piping myself- it ran out clear.) The automatic water feeder has recently come on after the system has shut off. The water level is in the middle of the sight glass.

Boiler pressure- I will look at this tonight when I go home and run the system. Honestly, I have never noticed any movement in the gauge... 

I feel like by fixing a problem (leaking pipe)- I opened a can of worms. It's frustrating.

Thanks for your help. It is difficult finding people with knowledge of how steam systems operate and even more difficult finding someone willing to work on one.

-Stephanie