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# boiler sizing

Member Posts: 6,928
The I=B=R NET rating ALREADY assumes 15% of gross capacity is lost to the piping system. If the piping is far-flung and/or uninsulated or poorly insulated that might not be enough. If piping is compact, insulated and/or extremely well insulated perhaps too much. If "average" it should be reasonable.

• Member Posts: 398
boiler sizing

I am trying to check the edr of my one pipe steam. can anyone clear up the rating of my boiler and the take up piping. Boiler is rated net i=b=r 2021 sq ft . I am checking the size of my boiler and edr load to see if I can add more radiation. Does the I=B=R net already take into account the pipe, so that the 2021sq.ft. is all available for radiators? thanks. T

• Member Posts: 398

My contractor is telling me that is has to do with the efficiency of the boiler. IE the difference between the gross and the net is the efficiency of the boiler. If I understood his calculations I should take the net and subtract 20% for pipe to see what is left for radiation? assuming all is tight and reasonable. Is this wrong?
• Member Posts: 6,928

Boilers usually have 3 ratings: input, output and net (frequently I=B=R) output. Input is the amount of energy consumed. Output (usually DOE or CSA) is the what you can receive from the boiler in ideal conditions; e.g. gross output from which you can compute gross efficiency. The net I=B=R output includes a "pickup factor" to compensate for the piping system.

Input will be highest. Output will be lower. Net output will the lowest.
• Member Posts: 1,231
Mike's got it right, except..

> The I=B=R NET rating ALREADY assumes 15% of gross

> capacity is lost to the piping system. If the

> piping is far-flung and/or uninsulated or poorly

> insulated that might not be enough. If piping is

> compact, insulated and/or extremely well

> insulated perhaps too much. If "average" it

> should be reasonable.

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