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pick up factor

Paul S_3
Paul S_3 Member Posts: 1,257
Can someone explain when I should add a pick up factor when sizing a steam boiler....for example on a estimate today I measured 455 sq ft of radiation....nothing is insulated its a one pipe system ....should I get a boiler for 455 sq ft (109000 BTUs)? Or should I add a factor thanks Paul s
ASM Mechanical Company
Located in Staten Island NY
Servicing all 5 boroughs of NYC.
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  • vaporvac
    vaporvac Member Posts: 1,520
    Included in specs...

    I'm a homeowner, but when we sized my replacement system, I believe the manufacturers included the pick-up factor in their calculations so you don't have to add it in twice. Just pick the boiler that most closely matches the edr. Others, please correct me if I'm wrong.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • Rod
    Rod Posts: 2,067
    Understanding Boiler Rating Charts

    Hi - Reading a boiler manufacturer’s rating chart can be a bit confusing. I’ve attached a typical manufacturer’s rating chart below. 

    The following are 3 methods of comparison. (Note - the Net IBR ratings, already have the “pickup factor” calculated in to the displayed figure)

    1. If you know the total EDR of your radiators in Square Feet, you can go straight to the IBR Steam sq.ft. column in the ratings.  (The “pickup factor” is already included)

    2. If you know the Total BTUH Load of your radiators, you can go straight to the Steam MBH column. (The pickup factor is already included)

    3, The only time you need to add the pickup factor is when you are using the DOE MBH Output Rating. You would only do this if you, for some reason, needed to change the pickup factor percentage.

    All 3 methods arrive at the same boiler size. Most people use the first method, comparing Square Feet of Steam.

    - Rod
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