Gas Fired Boiler
Harsco Industrial, Patterson-Kelley Technical Service 1.877.728.5351
68
Appendix 2: Boiler Altitude Derate Schedule
For installations over 2000 ft. elevations, a derate schedule is applied. The boiler input rating must be reduced
by
4% per 1000 ft. which is illustrated in the graph below.
Derate procedure is as follows:
With the boiler at high fire, adjust the gas valves (
as described in
Section 3.10.4
) to get 5% O2 in the flue gas. If
this cannot be achieved, perform the following steps:
•
If the O2% is too high, then the inlet gas pressure should be adjusted to the minimum pressure allowed,
typically 5” wc The gas valve should be adjusted to obtain approximately 5% O2. If the O2% is still too high,
the fan speed may be lowered. This procedure should only be performed by factory trained personnel.
•
If the O2% is too low, then the gas valve settings should be reduced. This procedure is also described in
Bulletin 06-08.
Summary of Contents for SC-2000
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