Bosch BGH96M080C4B - High Altitude Derate

36
|
Installation Instructions
Bosch 96% AFUE Condensing Gas Furnace - BTC 770503101 J (06.2023)
9.2 High Altitude Derate
Alternately, in high altitude applications, a standard derate for altitude from
National Fuel Gas Code ANSI Z223.1 of 4% per 1000 feet above sea level may
be taken. Refer to the most recent version of ANSI Z223.1 for correct gas orifice
based on your specific application. The orifices must be selected using the
specifications listed in the table below. The furnace derate is 4% for each 1,000
feet above sea level.
Table 15 is based upon a heating value of approximately 1,000 Btu/ft³.
In Canada, the input rating must be derated by 10 percent for altitudes of 2,000 ft.
to 4,500 ft. above sea level by an authorized Gas Supplier or Dealer.
When an appliance is installed at elevations above 4500 ft, the certified high-
altitude input rating shall be reduced at the rate of 4% for each additional 1000 ft.
In some areas the gas supplier may artificially derate the gas in an effort to
compensate for the effects of altitude. If the gas is artificially derated, the
appropriate orifice size must be determined based upon the BTU/ft³ content of the
derated gas and the altitude. Refer to the latest version of NFPA54/ANSI Z223.1
and information provided by the gas supplier to determine the proper orifice size.
US installation
Input Rate
KBTU/H
Number of burners
Elevation (Ft) Elevation (Ft) Elevation (Ft) Elevation (Ft) Elevation (Ft)
0-2000 2000-4000 4000-6000 6000-8000 8000-10000
NG** LP* NG** LP* NG** LP* NG** LP* NG** LP*
60 3 45 55 47 56 48 57 49 58 50 59
80 4 45 55 47 56 48 57 49 58 50 59
100 5 45 55 47 56 48 57 49 58 50 59
120 6 45 55 47 56 48 57 49 58 50 59
Table 15 High Altitude Derate Orice Size Chart (Natural and LP Gas*)
* LP orifice based on 10 in. WC manifold pressure
- The input to the furnace must be checked AFTER reorificing.
** NG denotes natural gas
Canada installation
Input Rate
KBTU/H
Number of burners
Elevation (Ft) Elevation (Ft) Elevation (Ft) Elevation (Ft) Elevation (Ft)
0-2000 2000-4000 4000-6000 6000-8000 8000-10000
NG** LP* NG** LP* NG** LP* NG** LP* NG** LP*
60 3 45 55 47 56 48 57 49 58 50 59
80 4 45 55 47 56 48 57 49 58 50 59
100 5 45 55 47 56 48 57 49 58 50 59
120 6 45 55 47 56 48 57 49 58 50 59
Table 16 High Altitude Derate Orice Size Chart (Natural and LP Gas*)
* LP orifice specification based on 10 in. WC manifold pressure (as specified on the
unit's rating plate for LP).
- The input to the furnace must be checked AFTER reorificing.
** NG denotes natural gas
For Canada applications, regulation requires 10% derating
between 2000-4500 ft. When an appliance is installed at elevations
above 4500 ft, the certified high altitude input rating shall be reduced at
the rate of 4% for each additional 1000 ft.