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Re-piping condensate returns: Fixing banging.

redplumber
redplumber Member Posts: 7
edited October 2022 in Strictly Steam
Dear Friends,

I'd like to thank you once again for this wonderful community!

With the heating season upon us, it's got me thinking about fixing issues and improving. Here is my current layout, drawn as a plan:




The system has 2 main condensate returns: one on the north and one on the south of the building.

The one on the north side is setup as follows:
  1. there is a main line vent (pictured, has fiberglass insulation in the pic)
  2. it flows into an F&T Trap Hoffman 55 (pictured)
  3. the trap releases condensate into the pump periodically which pumps it back into the boiler (pictured the end of the line that feeds into the boiler)
The south side:
  1. There is a main line vent (pictured, the pipes are painted silver, but the vent is hidden because of the picture angle)
  2. it goes straight down into a 1" black steel line (pictured, painted silver)
  3. that line goes for 20' to 30' approximately until it goes underground
  4. the underground pipe is 1" K copper line
  5. the K copper line somewhere converts to steel, which feeds into the new condensate pump

My questions/problems are:
  • The south side line tends to bang (water hammer). What can I do to fix it? Is it as simple as adding a F&T trap on that drop?
  • Is it possible to remove the condensate pumps? It feels like I can pipe the condensate directly into the boiler.
  • If it is not possible to remove the condensate pumps: is it possible to eliminate the underground K copper line by moving the new condensate pump where the pipe goes underground and installing new copper piping vertically up the wall and through the ceiling?
The first one I'd like to fix within the next month (before the cold season starts).

The next problems are long-term projects that I'll tackle.

Thanks in advance! The pictures of the items mentioned are below. I included a link from my first post, showing the new condensate pump install pictures.












For additional details (better pictures) on the new condensate pump, I received help installing it here:

https://forum.heatinghelp.com/discussion/185282/condensate-return-pump-post-installation-questions





Comments

  • Jamie Hall
    Jamie Hall Member Posts: 20,467
    You have, it seems to me, an interesting hybrid -- one line with an F&T and a condensate pump, and one line without the F&T which may -- or may not -- have had a condensate pump.

    The thing to remember here is that in the line without the F&T steam -- and boiler pressure -- will get into that return line. Can't help it. At a guess I'd say that that's where the hammering is coming from. So... the simplest thing to do will be to put an F&T on that line. Will that fix the hammering? No guarantee. But it's a good shot at it.

    Now taking a longer view, yes it is very likely that you could lose both condensate pumps and both F&Ts and pipe the whole thing by gravity, but I would suggest larger return pipes for that -- maybe inch and half. Or you could move that one pump and eliminate the underground line (might not be a bad idea anyway, does it leak? Do you know?) but, other than eliminating the underground line I'm not sure what is to be gained by doing that.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • retiredguy
    retiredguy Member Posts: 684
    edited October 2022
    In your first drawing of the north and south return piping that F&T trap just before the condensate return pump for the north side of the building, should not be there. Adding a trap at the end of a condensate return is not a "fix" for bad traps in the system. You should fix the upstream problems which are probably bad traps both drip and radiation.

    For the south side of the building I would move or add a condensate pump set to just before the place where the piping goes underground and pipe the pumps discharge overhead. Underground and hidden piping is always a problem. Make sure that the underground piping is not collecting any other condensate lines. Also, you can't add a stream trap at the end of the steam supply. They are sometimes called "master traps" and NO, they do not fix anything. As I said above, you have "to bite the bullet" and fix the problems in the system.

    One thing I would like to recommend is to utilize sch80, also called extra heavy on all steel lines below the boiler's water line. standard piping on condensate lines has a short life span.
  • redplumber
    redplumber Member Posts: 7
    Thanks for your comments!

    Or you could move that one pump and eliminate the underground line (might not be a bad idea anyway, does it leak? Do you know?)


    The underground K copper line does not leak. It had a leak previously, but I fixed it with the new condensate pump installation. Once I connected it properly, I did a slight pressure test with a compressor before installing the new condensate pump. My fear long term is that if it leaks, I'll never really know. I'm not worried about it for a few years. The K copper line has been there for years.


    Make sure that the underground piping is not collecting any other condensate lines.

    I don't believe it is because I pressure tested the line by plugging one end and pressure testing the end that flows into the new condensate pump. I believe it held a few PSI for a few minutes (I didn't do a long term test), good enough to confirm there were no major leaks anywhere underground.

    One thing I would like to recommend is to utilize sch80, also called extra heavy on all steel lines below the boiler's water line. standard piping on condensate lines has a short life span.


    I did re-pipe the approximately 30' of 1" black steel pipe on both sides of the building. I went to a local specialty shop and bought american made pipe, which was better than the pipe at home depot.

    So there's a thicker pipe that I should've used.... How long do you think this new piping will last? What's your opinion of using L or K copper piping on condensate return lines (it's a lot easier to work with)?
  • redplumber
    redplumber Member Posts: 7

    In your first drawing of the north and south return piping that F&T trap just before the condensate return pump for the north side of the building, should not be there. Adding a trap at the end of a condensate return is not a "fix" for bad traps in the system. You should fix the upstream problems which are probably bad traps both drip and radiation.

    From my understanding, the F&T trap needs to be there. If I were to remove it, I assume that steam would fill the room because the condensate pump reservoir has a pipe open to the atmosphere.

    Am I wrong? How would I improve this setup?

    Here is a picture of the end of the north line, where the F&T trap is shown as well as the main vent. The old condensate pump is not shown, but the pipe from the F&T trap falls into the pump's reservoir.

    (I removed the busy/non-essential elements from the image to improve clarity)



  • Jamie Hall
    Jamie Hall Member Posts: 20,467
    If that pipe to which the F&T is connected is, in fact, a steam main or steam main extension, then it does need the F&T since you have a vented condensate receiver. If it were a gravity wet return system, you would neither need it nor want it.

    If, on the other hand, that pipe is a dry return, you don't want it -- you are double trapping -- and if steam is present in a dry return it indicates problems elsewhere in the system, such as bad traps elsewhere, or missing orifices, or simply running too high a boiler pressure blowing past traps or orifices or water seals.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England