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.

Rule of thumbs

j a_2
j a_2 Member Posts: 1,801
I am not a huge fan of rules of thumb to finalize a question...However just to confirm my understanding, can it be said in ONE pipe steam, counter or parell flow, if you have an existing 2 inch main then your replacement boiler should not be bigger than 387 sq. ft. of steam...Does that make sense?  thanks  J A


  • crash2009
    crash2009 Member Posts: 1,484
    Yea it makes sense

    that you need a 2" pipe for 387 EDR, but it does not make sense that you can estimate boiler size by the size of the existing main.  What if the previous installer installed 2" just for the hell of it. 

    I think it's best to use my thumb to hold the tape measure while measuring the radiation of the building.
  • j a_2
    j a_2 Member Posts: 1,801

    Sorry for any confusion, but the answer I want to confirm is this, if you have a 2 inch main you should not install a steamer with anything over 387 sq. ft. of steam, give or take a little.. espically a counter flow system   Thanks  J A
    STEAM DOCTOR Member Posts: 1,943
    main size

    According to Lost Art a 2" main can handle 386 square feet EDR in a parallel flow system. Counter flow systems need mains one pipe size larger then parallel flow. This has nothing to do with the sizing of the steam boiler. The steam boiler is sized to the connected radiation. Are you sizing a boiler or are thinking about replacing or adding on to a main?
This discussion has been closed.