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Is this EDR calculator as good any other?

Jack M
Jack M Member Posts: 229
edited April 2015 in Strictly Steam


  • BobC
    BobC Member Posts: 5,477
    That looks fine. I would pretty much ignore the BTU's for steam and stick with trying to match the sq ft of steam the boiler is rated for to the total system EDR.

    Keep in mind the boiler rating hides the 33% pickup factor so you may want the boiler sq ft to be less (10 to 20% less) than the system EDR, it depends on the system layout and how well the basement piping is insulated. You don't want the system to short cycle but not having enough steam to heat the house on a very cold day is worse than short cycling.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • FranklinD
    FranklinD Member Posts: 399
    I actually have that one saved on my desktop and used it to compute the EDR of all my radiators prior to my boiler replacement last year.

    I think it's as good as any...I have a hot water system and just wanted to compare the installed EDR to my calculated heat loss of each room in my house. Led to some interesting observations.
    Ford Master Technician, "Tinkerer of Terror"
    Police & Fire Equipment Lead Mechanic, NW WI
    Lover of Old Homes & Gravity Hot Water Systems
  • Jason_13
    Jason_13 Member Posts: 304
    I use the one in the Burnham Heating Helper.
  • Jack M
    Jack M Member Posts: 229
    Jason said:
    This is a nice resource. I had not come across it. Lots to read up on here.
    The EDRs listed match what I was using, and that is comforting.

  • Dave in QCA
    Dave in QCA Member Posts: 1,785
    edited April 2015
    I like this chapter which I copied years ago from and ASHRAE guide. It makes a distinction between "large tube" and the slenderized "small tube" cast iron radiators. Often times the large tube version is referred to as small tube, leading to much confusion.

    Other than this, Dan's EDR book is great as well as the original manufacturer handbooks. One type that is always off the charts is the various "flue" radiators. Particularly the American Radiator "Italian Flue" and the "Window Flue" radiators. Ratings are higher than similar sized radiators.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.