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.

Hydronic radiant heat layout

1850s house, been in there for about a year. Has radiant heat, redoing much of the house now. Since the floor joists are exposed I feel like I should replace the copper pipes since they are at least 80 years old. Tongue and groove flooring going in soon and I don't ever want to have to rip the floors up to get to the old copper. Two floors of radiators, with single 1.25" supply line and a 1.25" return line in the basement. Each radiator has its own lines running off the main lines in the basement. The second floor has four radiators total, each on 3/4 inch lines. Should I run a 1-inch supply and 1/2 line to each radiator or just replace as it was, four sets of pipes each running off a main. I'm doing copper since when we moved in there was a squirrel/mouse problem, since resolved, but I don't want them chewing through pex if they ever make their way back in.


  • hot_rod
    hot_rod Member Posts: 21,855
    Radiant heat? Or radiators?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Big Ed_4
    Big Ed_4 Member Posts: 2,697
    Wood floor radiant should be near constant heat temperture and maintain in house humidity .

    The radiator piping , we need more info in knowing your system
    I have enough experience to know , that I dont know it all
  • psb75
    psb75 Member Posts: 807
    We have an 1850's farmhouse (in the family from the beginning) that we recently renovated. Kept all of the cast iron radiators and added more for 20 total. Added some panel rads and heated towel bars as well. All run off a Viessmann mod/con boiler w/ home-run manifolds with 1/2" pex to and from rads. Two zones: first floor, second floor. And...no thermostats. Boiler runs off of outdoor reset. Constant circulation. Works great.