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JayHP33 Member Posts: 2
Total heatloss 51000 (BTUH) what range of boiler is acceptable?

CI only.



  • Sizing

    You want a boiler that has an I=B=R rating of 51,000 BTU or as close to that as possible.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Jason_13
    Jason_13 Member Posts: 304
    DOE output

    When you do a heat loss you use the DOE or Gross output not the lowest number net output.
  • Gordy
    Gordy Member Posts: 9,546
    edited April 2014
    My interpretation

    Of which output number to use is if the boiler and piping is in a conditioned space use DOE output, if the boiler, and piping is Not in a conditioned space use I=B=R.

    A heatloss should always be done regardless, and has no bearing on which output number you use.

    Not disagreeing with Alan just trying to point out the difference between the two output numbers.
  • icesailor
    icesailor Member Posts: 7,265
    edited April 2014
    Boiler Ratings:

    You can use any number you want. Even what some very old times did by holding a pencil at arms length, and a certain distance from the building, and deciding how much of the house the pencil covered. Then, add a section for good measure.

    What they tell you in the IBR courses and the IBR H-22 heat loss guide and the #200 piping design manual is that there are three numbers. Gross Input, how much energy you can put INTO the boiler. The DOE is a number that the hated Gub-Ment came up with to make all things equal and stop manufacturers from over rating their boilers. The THIRD measure, IBR is a rating tested and established by the IBR that would always be lower than the other two ratings. Because, when installed, they allowed 1.33% subtracted for piping and pick-up. So unless you had some unusual piping situation, if you had a heat loss of 60,000 BTU's per hour, a boiler with a IBR rating above that, would do the job.

    You can use the DOR number but you need to add for piping and pick-up.

    You can do the math yourself. There's a resistance value to everything. Add up every fitting, valve, boiler and piping to get a total resistance and subtract some factor from the DOE to get the friction heat loss through the system that the boiler will see.

    Or use the IBR number. It will never be wrong.
  • SWEI
    SWEI Member Posts: 7,356
    If you run a mod/con on ODR

    Even the DOE rating will have a significant safety margin.
  • HDE_2
    HDE_2 Member Posts: 140
    edited April 2014
    Old news but don't be looking for the IBR Ratings any more

    On January 1, 2012, all I=B=R marks were replaced by the AHRI Certified mark. Manufacturers participating in the I=B=R programs must use the AHRI Certified mark, but they have the option of simultaneously using the I=B=R mark until January 1, 2014.

    The GAMA Efficiency Rating Certified mark was replaced by the AHRI Certified mark on January 1, 2013, for commercial water heaters, residential water heaters, and direct heating equipment certification programs.

    All former ARI Performance Certified marks have been replaced.

    No more IBR rating (or AGA), it is now NET AHRI CAPACITY

    Input – Efficiency Loss = Heating Capacity (DOE Output) – 15% Piping Loss = Net AHRI Capacity