New Install Weil Mclain 2 Pipe Steam - Water Hammer

10uglymen

Good Day,

Recent Weil Mclain Steam boiler install and am having issues with obnoxiously loud water hammer from condensate tank into boiler as well as 3 radiators which are all grouped together are working sporadically. Contractor reused the existing condensate tank and pump (which they shared with me is oversized for the system). They added a valve to throttle back the volume of water going into boiler but am still having issues.

Regarding the 3 radiators sporadically working I have replaced the discs in the traps and am thinking the issue could be the crossover trap which is at the end of the run in the basement. I know that the trap hasn't been worked on in over 50 years as it was behind a paneled wall which I recently opened up. I plan on working on the trap this week to see what the internal parts look like.

I am planning on insulating all of the piping this week. The system is a 2 pipe steam with primarily Dunham traps which I am in the process of replacing the discs. I am looking for feedback on new install as well as how to reduce the water hammer.

I will also take the time to properly skim the system. I am seeing sediment in the steam in the sight glass.

I am looking for feedback on install as well as advice. I live in western New York.

Thanks in advance and Happy Holidays!

Jamie Hall

What do you know! The pressure control is set about right! A minor miracle… I'd probably set the main scale to 8 ounces, but where it is should be OK.

Overall the install looks pretty decent.

That crossover trap is probably very important…

However. Why the condensate tank at all? That system, on those pressures, should be able to run entirely by gravity. But… it's there. So the next question is, where do any drips from the steam mains or dry returns go? With the condensate tank you have atmospheric pressure, or very close to it, in any wet returns, and steam main drips may not have a usable water seal. Can you look around for me and see how condensate from the dry returns and steam mains gets back to the tank?

10uglymen

Thank you for responding. I believe they used the condensate because it was used in the previous installation. Are you thinking I can surpass it and tie directly into the boiler?

I attached pics of the dry returns as they connect to the condensate tank below. And pics of the crossover trap which I think is causing me issues. I am removing and replacing this week. Note the 3 radiators that are slow to heat up (took over 3 hours before they got warm) are to the left of the crossover trap.

Thank you again for you sharing your expertise and knowledge.

Image 1 - supply to 3 radiators that are taking over 3 hours longer to heat than others, crossover trap is on right side.

Image 2 - the 2 dry return lines tie together which feed condensate tank below.

Image 3 - pics of supply lines to slow to warm radiators

Image 4 - another pic of dry return lines

Image 5 - close-up of dry return lines connection before dropping to condensate tank

Image 6 - crossover trap that likely has never been opened.

dopey27177

The banging in the condensate tank?

check if the piping to the condensate receiver has been changed.

the dry returns must be piped at the highest port in the condensate receiver.

If that piping is connected below the water line you will get banging if steam is entering below the water line or loud gurgling if air is entering below the water level.

it is also a good idea to replace the elements on the cross over traps.

jake

10uglymen

Thanks for your response and yes the dry returns are piped at the highest point. I spoke with Weil Mclain and he mentioned that a likely cause could be the oversized pump is pushing to much water into the line which is feeding the boiler. A valve was installed to throttle back the volume of water, and I am going to reduce the flow to see if that helps, if not I may need to right-size a pump.

Jamie Hall

Ah… I don't like that pipe in, I think the third, picture with a spray bottle on it. That pipe will have steam in it, if it's tied back to the condensate receiver. It was likely, once upon a time, a wet return. It isn't any more…

10uglymen

Jamie - FYI The system was originally coal fired and converted to oil which I inherited, and I am on my second replacement steam boiler. The Smith lasted 22 years and ended up getting a crack in it.

What do you mean by your comment, and do you have a suggestion to address this? I am 100% positive that it is tied into the condensate tank. Thanks

Jamie Hall

Whether that one pipe is a problem or not depends on whether any other drips are tied into it, and whether it allows steam to get into the condensate receiver (which I doubt — you would have noticed it!). There are ways to solve any problems, but it depends on whether it is a problem — it may not be. I'm twitchy about water levels! The easiest solution is to create a false water line for that pipe— if it is a problem at all.

10uglymen

The wet return does not have any other drips tied into it. The wet line that you are referring to is within a foot of the 3 radiator supply lines that aren't getting hot are to the left of it. I am hoping that replacing the disc in the crossover trap which is next to the wet line will address the issue. Thanks again for the feedback.