P-K Storm
TM
Gas Fired Boiler
Technical Service 1.877.728.5351
Revised: June 26, 2020
Released: June 26, 2020
©
Patterson-Kelley 2020
All Rights Reserved.
2691000273 P-K Storm ST2500-ST4000
Installation and Owners Manual Rev A.docx
Page 86
Appendix B
– Boiler Altitude Derate Schedule
For installations over 2,000 ft. elevations, a derate schedule is applied. The boiler input rating must be
reduced by
4% per 1,000 ft. which is illustrated in the graph below.
Although the appliance’s capacity is reduced due to the lower air density, the combustion tuning should
follow the standard combustion guidelines of
. Tune the combustion for the same O
2
and CO
2
levels as discussed in