Boots wrote:Why is it that I will get only 80% of the manufacturers stated net output? The Gross out put (according to Keystoker) is 120K btu. I assumed the Net output was the "real number" the you could expect to achieve .
To me it looks like there is an inconsistency in the ratings for the KAA-4 (and for the KAA-2, which was discussed in another thread), as presented on the "Products" page of the Keystoker website, that might(?) clarify things. For all boilers larger than the KAA-4, the "gross" btu/hr value presented corresponds precisely to the values in the "Total Capacity" columns. For example, the 144,000 gross btu/hr shown for the KA-6 is precisely equal to 600 s.f. steam x 240 btu/hr/s.f. steam (i.e., the standard heat transfer rate for steam), and also to 960 s.f. hot water x 150 btu/hr/s.f. hot water (transfer rate for hot water). The same correspondence exists for all of the bigger boilers. This indicates that the "gross" values being reported for those boilers are gross output btu's.
For the KAA-4, however, the listed total capacity of 600 s.f. hot water would translate to only (600 x 150=) 90,000 gross output btu/hr. Applying Keystoker's 1.18 pickup factor, the net btu's available to the installed radiation would be about 76.3k btu/hr. Alternatively, Keystoker's recommended load of 525 s.f. hot water would translate to 78.8k btu/hr. Either value is quite a bit lower than the 120/105 values appearing in the table.
Hope this helps.