boiler sizing

kev

I have a system with 371 sq. ft. of radiation. If I multiply by 240 = 89,040 BTU.  Multiply x 1.5 pick-up= 133,560 BTU.  The boiler brand I would like to use lists AHRI NET RATINGS in sq. ft. and they have one sized at 381 sq. ft.  122 MBH. Literature states net ratings use pick-up factor o 1.333.

I think this boiler would be correct for the job and would like to confirm that I am using the right math.

Thanks.

JStar

Boiler size

Are the pipes insulated? Completely insulated? If so, I only add 15-20% pick-up. If not insulated at all, I'll add 33%.



So multiply 89,040 by either 1.2 or 1.33. Take that number and divide it by 0.82 (replace 82 for the actual efficiency) to get your boiler input.

Dave in QCA

Short way around the barn....

Jstar is correct. But, if you have insulation on the pipes, 0.34 pickup is recommended by Dan in tlash, or at least that is what I recall. And, since almost all boiler manufacturers use a 34% piping loss and pickup factor for steam boilers, all you really need to do if find a boiler that has an EDR or sq ft rating that is very close the the EDR or sq ft of your system. It looks like the boiler you're looking at is about as close as you could hope to come.

kev

thank you

Thanks for the reply!  I am confident now.