Boiler Oversizing %
Boiler Oversizing %
(OP)
The question is about a steam boiler replacement happening in Massachusetts. A limitation stating, the replacement boiler capacity must not exceed 125% of the total building load, was brought up by the inspector. To the best of our ability we were unable to locate this limitation in any code. Does anyone know about this limitation or where it can be found?





RE: Boiler Oversizing %
RE: Boiler Oversizing %
RE: Boiler Oversizing %
If you need to satisfy the inspector, you'll have to calculate the building's heating load. If there's not enough info available (such as as-built drawings), get your field clothes on and get to measuring and interviewing.
Good on ya,
Goober Dave
RE: Boiler Oversizing %
Intern, why not provide a block load of the building? Shouldnt be too time consuming. You dont need a space by space analysis.
knowledge is power
RE: Boiler Oversizing %
RE: Boiler Oversizing %
RE: Boiler Oversizing %
503.2.1 Calculation of heating and cooling loads. Design loads shall be determined in accordance with the procedures described in the ASHRAE/ACCA Standard 183. Heating and cooling loads shall be adjusted to account for load reductions that are achieved when energy recovery systems are utilized in the HVAC system in accordance with the ASHRAE HVAC Systems and Equipment Handbook. Alternatively, design loads shall be determined by an approved equivalent computation procedure, using the design parameters specified in Chapter 3.
From the inspector,"he wouldn't have a problem with redundant systems if the control strategy takes care of preventing over firing."
Thanks for the help
RE: Boiler Oversizing %
I was actually sitting within arm's reach of 90.1 and didn't bother to open it up...
A mea culpa,
Goober Dave
RE: Boiler Oversizing %
They should have published outdoor design temperature for your local climate for equipment sizing. This will establish the maximum heating load.
A boiler is ALWAYS way oversized, we size for say 0 degrees outside (99.6% for our area), but the boiler is well oversized when OA is around 40 for example.
90% of the time, boilers operate at no more than 60% of building heating load.
I think his comment should've been specific about sizing the boiler for the published design OA temp. say if it is 10F, then you should not design for 0 degrees OA, typical of designers built-in safety factors.
ASHRAE is not a code. Cannot quote ASHRAE as a reference with code offcials.
RE: Boiler Oversizing %
RE: Boiler Oversizing %