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Calculating Radiation Load

Scot Member Posts: 7
I am trying to calculate the Radiation load of my radiators and piping (one pipe steam). I bought Dan's EDR book and found my radiators. The total EDR is approx 200 SqFt. (It was 232 when we bought the house, but we removed one radiator)

I have 50ft of 2in (nom) main piping (Insulated), and 13 ft of 1in (nom) return piping (Insulated). I'm not sure how to apply the pick up factor. Do I use 200(1.33) for a total radiation load of 266? Or is it 200 + 200(1.33)= 353?

Either way these numbers are grossly lower then the 650SqFt rating of the new boiler that was recently installed. We have the system running real nice right now. I want to calculate this load so my contractor can make sure the burner is set at the correct rate.



  • Bob W._3
    Bob W._3 Member Posts: 561

    Scot, look at the ratings charts for some boilers, like Weil McLain, Burnham, Peerless, Smith, Slant Fin, etc. etc. They show the rating in sq. ft. as well as AGA input, DOE, IBR, etc. The pickup factor is already in the rating. Most will indicate that they are using a 1.33 pickup factor. Look at this chart for example:


    It has the input rating, the DOE rating and the net rating, which is the steam left to heat the rads after the pickup factor for the piping. But all you need to see is the rating in Sq. Ft., which already includes that factor.

    If you have 200 sq. ft. of total EDR, you look for a boiler that supplies that much (or just slightly more), per the ratings. Don't multiply it.
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