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.

steam EDR calc: piping?

I'm sizing new boilers for some old steam-heated buildings and using Dan's EDR book for reference on the radiators' heat output. One thing I'm not clear on is, what about the supply piping? I saw in another reference the implication that "the pipes are included in EDR ratings," but Dan's book is silent on that question (as far as I could tell). The piping is generally inaccessible, so precise measurements are not feasible. How is supply piping handled? If I get 840,000 Btuh of total radiator EDR, is a 840,000 Btuh output boiler the thing I should seek? Thanks in advance.

Comments

  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,513
    I get into this at length

    in The Lost Art of Steam Heating. In rating boilers, manufacturers add a pick-up factor for the piping connecting the radiation to the boiler. The standard pick-up factor is 1.33. That means they're taking the actual radiation load and multiplying it by 1.33 to arrive at the Gross rating of the boiler. If the pipes aren't insulated, or if radiating has been removed, it's wise to use a pick-up factor of 1.5 instead of the 1.33. In this case, you'd measure the radiation, multiply by 1.5 and then select the boiler from the GROSS (or D.O.E. Heating Capacity) column.

    It always pays to insulate steam piping, both on the supply and the return.
    Retired and loving it.
This discussion has been closed.