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Thread: changing supply and return lines

  1. #1

    Default changing supply and return lines

    Hey guys hopefully I can make this clear enough to understand. I have and older house built in the 50's. Just replaced the boiler about 2 years ago and the heat just isn't that great. I have from the boiler at the rear of the house two 2" pipes running to the front of the house. One is the supply and one is the return. There are four tee's in the supply line running to each of the four radiators in the house and four tee's in the return coming from each radiator back to the boiler. Am I right saying that the system is not a loop? Shouldn't the supply run from one radiator to the next and then back to the boiler?
    Can I remove all the lines in the basement and start at the boiler with 1" pex and then continue to the first radiator then to the second and so on then back to the boiler?
    Thanks Bill

    first pic is existing
    second pic is what i want to do
    Attached Images Attached Images   

  2. #2
    Plumbing Contractor for 49 years johnjh2o1's Avatar
    Join Date
    Aug 2009


    What you have is a two pipe system. If your radiators are cast iron it would not be advisable to loop from one to the other. It sounds like you have air in the system or the circulator isn't working. Was the heat always inadequate at the far end of the house or just after the boiler was replaced?


  3. #3


    Hey John thanks for the response. I purchase the house a few years ago and the heat just isn't what I think it should be. The circulator is brand new as is the boiler. There might be a little air in the system though i do bleed them at the radiators now and then, not much air though. The water pressure is a little low at my house, if that would affect anything, working on replacing service in a month or so. My sons room seems to be the worst. The tee for his room is actually the closest to the boiler but the run does have a few 90 degree bends. Looks like it has been moved a couple of times over the years.
    What about if I installed a manifold near the boiler and then installed 1"pex to and from each radiator. If I seem hung up on the pex, I am looking to getting rid of the old pipe thats down there, its hanging low and i could use the headroom.


    Bill Bonetto
    Bonetto's Carpentry

  4. #4
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona


    There is no "piping" reason why your system should not heat properly, (in fact it is the one type of system which should ALWAYS work properly), therefore you need an "expert" to check it and see what is happening. It could be something as simple as a broken radiator valve.

  5. #5
    Engineer Furd's Avatar
    Join Date
    Jul 2007
    Wet side of Washington State


    I agree with HJ that there is no reason why your system should not be heating the house as well as it can with the limited number of radiators you have. It could be air in the system or it could be a circulator too small for the system or it could be that you simply do not have enough radiation in the house. Have you done any heatloss calculations? How is the overall energy efficiency of the house, meaning insulation, air infiltration and such?

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    It could be as simple as the operating temperature is set too low. Low is good (if the boiler can handle it) IF it can supply enough heat. If not, then you need to raise it. This is where an outside reset controller can help - it can adjust the set point of the boiler operating temperature to the outside and inside conditions.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  7. #7


    Hey guys thanks for all the info. I have been rethinking some things from all the responses. First off the heat does work well enough in most of the house, it's actually one or two rooms that don’t work well at all. I do have an issue with the existing pipes that run to each radiator. They hang about 6 to 8 inches off the ceiling in the basement right down the path that I mainly use. So they make you walk hunched over. I would like to move them. This is where most of my thought came in. I was told when I had the heating company replace the boiler that I could change the existing 2 inch pipes to 1 inch copper.
    Now I'm thinking that I want to put a manifold on the wall and use 1" pex to run to each radiator. In essence that is what I have now with the pipes running down the ceiling and branching off to each radiator. If I use a ball valve at each leg I could also regulate the flow to each radiator. I know I’m not a professional but I'm trying to buy a couple of more seasons till I change over to a radiant floor system.

    Bonetto’s Carpentry

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