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.

Hot water baseboard installation

Halbert Member Posts: 15
The house was built in 2 sections, one in the 1930's, with an addition in the 80's. I've lived in it for 3 years. Hot water baseboard heat. The way the baseboards are installed, there is a (I think) 3/4 inch header running around the basement walls, and the heater units are connected by tee's to the header, rather than the header turning up to the heaters and back down.

Why? The only logical reason I have would be to have warmer water feeding the last heater in the circuit--but it has the downside of less available flow to the heater units.

Is there any advantage to be gained by repiping the system to put all the heaters on a continuous line rather than off this header? (I think so, but I'm no expert).


  • GGross
    GGross Member Posts: 1,048
    it sounds like you have a monoflow system, it should be just fine, and if there are valves of some kind hidden by each baseboard branch it gives the benefit of being able to close off a single baseboard section if need be. Series loop (where your header flows through each section of baseboard) is more common now, mainly just because its cheaper to install
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,837
    edited April 2022
    You may find this booklet interesting. http://media.blueridgecompany.com/documents/ZoningMadeEasy.pdf
    the Mono-Flo system is explained starting on page 21. Just after explaining why non electric zone valves don't work very well on this type system. (the generic term for those tee fittings is "Diverter Tee". Bell and Gossett trademarked that name "Mono-Flo"

    If you have a 3/4" main loop around the entire basement, then the takeoff to each radiator loop would be 1/2". If you have a 1" or 1-1/4" loop around the basement then the takeoff to each baseboard might be 3/4".

    I'm thinking the system is operating properly since 1930s, so I agree with @GGross on the old system. The addition should be on its own loop not connected with the old section. You don't want to mess with the different pressure drop issues by trying to combine the new with the old.

    Me. Ed
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    EBEBRATT-Ed Member Posts: 15,524
    as @GGross said it is probably a Monoflo system. Check the tees if you can see them, the Monoflo tees will look different.

    Monoflo systems work fine. I had one in a house i owned for 35 years.

    When you drain the system, they can be difficult to bleed
  • Halbert
    Halbert Member Posts: 15
    ED: yes, there are two loops on the first floor, with a single tstat and zone valve. There are two 2nd floor rooms, each with it's own tstat and zone valve. There are bleed valves on each baseboard but no other valves I can find.
  • mattmia2
    mattmia2 Member Posts: 9,646
    It sounds like it maybe was monoflow with standing cast iron radiators that were replaced with baseboard during the remodel. Monoflow was really common mid century but fin tube baseboard was not yet all that common.(is your baseboard fin tube or cast iron?)

    The monoflow probably provides a little better balance and potentially can be balanced with balancing valves although that is tricky. The water cooling through a series loop makes the engineering for that topology more important if you want to to heat evenly.
  • Halbert
    Halbert Member Posts: 15
    I looked more closely, and yes, there are monoflo fittings at the connections. Thanks for the insight.