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Steam Repiping Help

steamkevin
steamkevin Member Posts: 10
in Strictly Steam

Hello,

About a year ago we had our basement finished and now every so often we get some water hammer.

I am working on figuring out how to repipe with minimal changes to fix the hammer but I am unsure if what I am thinking about will work so I'm looking for some review or other ideas.

Right now (behind some drywall) the piping looks like this. The boiler is to the left and there is a steam riser on the right.

original.jpg

The pipe on the right side of the picture has no pitch and the only return on this line is the vertical pipe in the middle.

return pipe.jpg

We added a small radiator to the left pipe on the left of this picture which contributes to the issue because I believe that condensate is very likely pooling at the corner until enough reaches to the vertical return pipe.

I would like to turn the elbow in the corner 90 degrees to point to the floor so that it creates a drop and then pitch the pipe on the right so that it's connected to that drop pipe. Then pipe the dropped pipe back to the existing return. Something like the following photo. Ideally the drop would be as small as possible to stay behind the finished wall.

proposed.jpg

However this will create a sort of circle/loop in this corner and I'm not sure if this will cause any issues. My main concern is that air could be trapped in either the corner or the drop pipe but I am not sure.

I could drop the entire pipe down to the floor and create an extension of the wet return which seems simpler but I am hoping to cut as little drywall as possible.

Comments

  • Ironman
    Ironman Member Posts: 7,667

    Is this a one pipe system?

    Why does a pipe that’s labeled “natural gas” have a steam vent on it?

    You need to post some pics that encompass the boiler and its near piping as well as the steam main that you’re referring to. In other words, the entire steam main in the basement.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • mattmia2
    mattmia2 Member Posts: 11,780

    image.png

    Turn this tee on a 45 or 90 down so the branch points down and connect to the drip from there. Put the vent on a riser to get it above the main from the connection to the drip or get rid of it and make sure the vent at the end of the main is sized appropriately.

    image.png

    Move the reducer or a bushing to this tee and run smaller pipe and an ell to the end of the main.

    Condensate is stacking up in the main because it has to fill until it can get over the branch of the tee and the reducer to get to the drip you show and the drip at the end of the main respectively.

    I assume that there is another drip and a vent at the end of the main.

  • Ironman
    Ironman Member Posts: 7,667

    This is probably the main issue: the reducing ell is causing water to pool up behind it.

    IMG_0890.jpeg
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • mattmia2
    mattmia2 Member Posts: 11,780

    I'm assuming the end of the main that we can't see has some way to drain condensate. I'm not sure that is the case. It may actually be a runout to a radiator that is huge for some reason.

  • steamkevin
    steamkevin Member Posts: 10
    edited February 5

    @Ironman the pipe just has a label on it. I imagine the contractor just wanted to use the piping.

    @mattmia2 there is no way to drain condensate besides the vertical pipe that you see. The pipe on the right is counter flow so water must come back down.

    Changing that vertical pipe into a tee will be difficult but it's possible. I'm hoping to keep the changes to the corner or after.

    It's possible that the reducing tee is the issue but in my original idea the elbow would be turned down so that would also fix that issue.

  • mattmia2
    mattmia2 Member Posts: 11,780

    If that is just a runout to a radiator, figure out what size it should be for the size radiator connected to it, repipe it in that size and slope it to the drip. The tee still needs to be oriented with the branch down or at a 45.

  • steamkevin
    steamkevin Member Posts: 10

    @mattmia2 The size should be right and understood about the slope. However I'm really hoping to not have to touch that vertical pipe to put it under the drop. Is it possible to use my original idea about adding a new pipe to connect to that existing vertical pipe? I'm hoping to do something like what I proposed.

  • mattmia2
    mattmia2 Member Posts: 11,780

    You just need to add enough slope to the runnout to the radiator for it to drain toward the drip. The end at the right needs to raise up a couple inches. You may need a swing joint or something similar at the tee to allow pitch toward the tee from both directions. the tee needs to rotate 45 to 90 degrees to meet the drip or be replaced with a tee that doesn't reduce at the branch and use a reducing ell to do the reduction.

    Because that is a reducing tee it is holding condensate in the main here:

    image.png
  • steamkevin
    steamkevin Member Posts: 10

    Okay I understand now, you want to angle that pipe so that condensate goes down. That could be done however I still think there will be condensate in the other pipe on the right.

    The pipe to the right is practically level and raising it will be tricky since it looks something like this

    IMG_9EB33C263AE8-1.jpeg

    Which is why I'm hoping to treat it as counterflow and have it come back to a new drip pipe in the corner.

  • mattmia2
    mattmia2 Member Posts: 11,780

    Oh, i see. someone did a hack job then buried it in the wall. if you can shorten the riser the end of that runout to the radiator can move up. I still don't believe that it needs to be anywhere near that large. You could add a drip there. Right now that huge section of pipe is venting through the radiator.

    The drip can run just below the existing runout but it has to connect to the existing drip below the water line. It can do some ells at the existing drip to drop down. If the connection isn't below the water line it will fill with steam and you could get some hammer in it.

  • Ironman
    Ironman Member Posts: 7,667

    The vent should be positioned away from the ell at the end of the main so that it won’t be damaged by any water hammering.

    It also should not be concealed since it has to be replaced periodically.

    IMG_0489.jpeg
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • steamkevin
    steamkevin Member Posts: 10

    I understand that the venting is not ideal but I am okay with less than optimal venting. I am able to access the vent if needed.

    @mattmia2 So you are saying that I can make a new drip pipe in the corner but I should connect it back below the water line, is that correct?

  • mattmia2
    mattmia2 Member Posts: 11,780
    https://forum.heatinghelp.com/discussion/comment/1840510#Comment_1840510

    Which corner? You could also put a vent at where you turn down to connect below the water line and vent that end of the main. Where does that riser at the end go? Does it feed just one radiator or several?

    The drip should be here:

    image.png

    I misunderstood and thought that was the part that was added.

    You could also possibly drill and tap the ell instead of taking it apart at the end.

  • steamkevin
    steamkevin Member Posts: 10
    edited February 5

    That riser feeds several radiators.

    I am hoping to not have to modify that elbow. Instead I would rather have the drip be in the corner. That way I'm hoping that the steam would come back as counter flow.

    image.png
  • steamkevin
    steamkevin Member Posts: 10

    To be clear, I want to make something like this change (assuming all appropriate slope)

    image (2).png
  • mattmia2
    mattmia2 Member Posts: 11,780

    You could just move the drip there if you can get everything to slope toward it and keep it down hill of any reductions. It doesn't have to drop down until it connects to the return so you can run it with slope toward the return just under the main. You could move the vent there too.

  • steamkevin
    steamkevin Member Posts: 10

    Yes I could move everything there but the current drip is behind drywall and I'm hoping to make as few cuts as needed.

    Is there any issue with leaving this previous drip there?

  • mattmia2
    mattmia2 Member Posts: 11,780
    edited February 5
    https://forum.heatinghelp.com/discussion/comment/1840531#Comment_1840531

    Not other than that's where you're going to have to connect the new drip unless you run another return back to the boiler.

    But you do need to either fix that tee or make sure the condensate that can't get out that tee because it is sideways and is a reducing branch can get to the new drip.

  • mattmia2
    mattmia2 Member Posts: 11,780

    It should connect like this so the drips connect below the water line:

    image.png

    Although that is probably less important on 1 pipe steam where the vent isn't in the right place anyhow than it would be on a 2 pipe system.

  • steamkevin
    steamkevin Member Posts: 10

    Yes this is 1 pipe steam sorry I don't think I ever clarified.

    I believe that tee to the return is slightly pitched however maybe it can be pitched more. I am hoping that with the new drip most of the condensate will go there.

    Since the banging is intermittent I think the existing pitch in that drip return is probably just barely enough.

    The drip return looks something like this. I guess I'm hoping I can connect to that existing connection but we will have to see.

    IMG_2874.jpeg
  • steamkevin
    steamkevin Member Posts: 10

    My last question is what if I connect above the water line? What issue would I likely run into?

  • mattmia2
    mattmia2 Member Posts: 11,780

    Possibly steam colliding with water and water hammer, possibly issues with steam taking the return to get to a vent and closing the vent before the air gets out of the main so some of it doesn't heat or is slow to heat.

    Your current issue is that the reductions in the horizontal have the drip on the high side of the reduction so that the condensate can never get out of the bottom of the main and to the drip/return then the steam hits that pool of condensate and collapses and causes water hammer.

    delcrossvsteamkevin

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