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.

Radiator Sizing

I am looking for help sizing steam radiators. My house was a flip and I am trying to get everything sized correctly. They just threw any radiator they had in. Different sizes and shapes. In one room there is a radiator with 4 sections and another room same size room with 12 sections. Is there a formula, cheat sheet available?


  • Jamie Hall
    Jamie Hall Member Posts: 22,952
    There isn't actually a formula sheet as such, but the way to approach this is to get an estimate of the heat loss from each room -- and that's not hard at all. Slant/Fin has a nice one here: https://www.slantfin.com/slantfin-heat-loss-calculator/. Don't worry about it's suggestions for baseboard and so on, but pay attention to the heat loss numbers it comes up with or each room. You can then use those numbers as a guide to which rooms need more heat and which less, and shuffle your assortment of radiators around accordingly.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England