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.

1/2” baseboard to 3/4”

mjfragano Member Posts: 1
I bought my house 2 years ago and all my baseboard heat is 1/2” fin tube. I will be gutting my basement and will be able to change the basement and first floor to 3/4” very easily. Yes my house gets warm in the winter but on really cold days it takes awhile to get warm. Also who ever installed it originally made the pipes too tight so when the pipes expand you hear them creak and the baseboards make a popping noise. My plan is to run all supply and return lines in the oxygen barrier pex and in between the rooms where I can 3/4” copper. Do you think we will notice a difference switching from 1/2”-3/4”?  Or is it a waste of money?  Thank you. Btw I’m not a plumber I’m an electrician but I am a extreme DIY guy and can do more than most. 


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,600
    You will want to look at this booklet. http://media.blueridgecompany.com/documents/ZoningMadeEasy.pdf
    There is a great explanation in the first few pages that will answer your question more thoroughly than a simple Yes or No.

    Bottom line is: the smallest diameter on any given loop will determine the flow rate on the water in that loop. If you are going to change the 1/2" copper elements in all the baseboards, then you may see a difference with 3/4" Baseboards and 3/4" PEX If you only change the PEX feeder to 3/4" but leave the 1/2" element in the loop, then you will see no difference.

    Pipe diameter will determine the heating capacity of the circuit (or loop).

    Yours truly,

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    EBEBRATT-Ed Member Posts: 15,345

    There isn't a huge difference between 1/2" & 3/4" fin tube but you will get more heat out of the 3/4". I have seldom seen much 1/2" fin tube, 3/4" is much more common and is usually what the supply houses stock
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    Before you start changing baseboard, maybe an overall assessment of what you actually need to heat the rooms and the house would be a better place to start.
  • hot_rod
    hot_rod Member Posts: 21,878
    I would second the suggestion to do a room by room heatload calculation. A free calculator at www.slantfin.com.

    Know that in some brands and models the 1/2 has a slightly higher output then 3/4 :)

    I would also consider the high output baseboard if you do replace. Getting the required SWT as low as possible will allow more heat source options and maximize the efficiency of your current boiler.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • bburd
    bburd Member Posts: 887
    On really cold days, nearly any house takes a while to get warm. That’s normal.

    What is your boiler’s supply water temperature or high limit setting? Does it use outdoor reset (ODR)?

  • mjfragano
    mjfragano Member Posts: 1
    If I was to change anything I would change everything to 3/4 no 1/2” would be left at all. But I need to use that calculator because I may need less baseboard than what I have now correct?  Also what’s the difference between regular and high output. I understand one puts out more heat than the other but is that what I would actually look for?
  • hot_rod
    hot_rod Member Posts: 21,878
    The higher output baseboard allows you to operate at lower supply water temperatures. This in turn allows for the use of higher efficiency boiler, or possibly a heat pump.

    One goal would be to heat your home comfortably and efficiently and at the least fuel cost.
    If you read the Idronics 25 I linked above, it explains the how and why of efficient low temperature hydronic systems.

    Panel radiators are another nice option, and each radiator could be individually control with a thermostatic valve attached. Some prefer the look and durability of panel radiators to fin tube. See examples in the Idronics issue mentioned.

    Changing pipe size may not be the answer to your question, no need to spend money on replacing baseboard until you have a proper heat load calculation and design idea worked out. Generally a 1/2 fin tube system requires a bit more pumping power. You may just need a different circulator to increase the heat output. The fin tube output charts give you that information.

    1/2" and in some cases 3/8 tube can adequately supply heat emitters like panel radiators.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream