Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

piping question

Recently had a boiler installed. Was put in on a deal that didn't let me voice my opinion(the price was right) Since the house was an old city steam we have a few dinosaurs left and this is one of them. Coming out of the boiler is 3 inch pipe. Goes up to about 6 ft high then when it goes over to catch the main header drops to 2 inch to join into the system. Seems the installer didn't want to deal with breaking one pipe to remove the tee that reduced to 2 inch just followed what had been there before(even though they told me they would change it). Question: is it worth having a plumber come down and change it back to three inch till the main header or should I just leave it as its been for the last 20 years


  • Jamie Hall
    Jamie Hall Member Posts: 19,928
    Not sure

    Where does it drop to 2"?  At the elbow where it goes from vertical to more or less horizontal?  Or somewhere on that horizontal run?  Makes a difference.

    If it drops to 2" at the elbow, and if it's running OK -- no water hammer, spitting vents, etc. etc., -- particularly if it's pitched away from the boiler -- I'd be inclined to leave it be.  Not ideal, sure, but it's working.

    If  it drops somewhere along the horizontal, how is the drop made?  If it's a concentric reducer, I'd be concerned as any condensate or wet steam which does make it up that 3" 6 foot vertical is going to pool behind the reducer and be a nuisance, if nothing else -- and could reduce overall efficiency.  You might be able to get someone to change out the concentric for an eccentric, placed with the flat side down.  Still not ideal, but...   If it's already an eccentric, with the flat side down, again I'd leave it be if it's otherwise working OK.

    You are quite correct, though, in thinking that the reduction in size (and then the increase back up when you get to the main header) is not good practice...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Yosef Guttman
    Yosef Guttman Member Posts: 8
    2-3 inch

    Yes it does reduce on the horizontal. I am not having any signifigant heating problems there. I do have a few radiators that bang on the other side of the house. C and one that doesnt get heat at all. Could that be related to this. I dodn't think so


This discussion has been closed.