General derating rules – Bryant 4-WAY MULTIPOISE 359AAV User Manual
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Table 6 – Natural Gas Manifold Pressure (in wc) 20,000 BTU per Burner*
MEAN ELEVATION FEET ABOVE SEA LEVEL Ft. (M)
HEATING
VALUE
BTU/CU.
FT.
0 to 2000
2001 to 3000†
3001 to 4000
4001 to 5000
5001 to 6000
6001 to 7000
7001 to 8000
(0 to 610)
(610.1 to 914)†
(914.1 to 1219)
(1219.1 to
1524)
(1524.1 to
1829)
(1829.1 to
2134)
(2134.1 to
2438)
Orifice
Mnfld
Press
Orifice
Mnfld
Press
Orifice
Mnfld
Press
Orifice
Mnfld
Press
Orifice
Mnfld
Press
Orifice
Mnfld
Press
Orifice
Mnfld
Press
700
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
44
3.7
725
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
44
3.7
44
3.4
750
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
44
3.5
44
3.2
775
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
44
3.5
44
3.2
44
3.0
800
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
44
3.6
44
3.3
44
3.0
44
2.8
825
--- ---
--- ---
--- ---
--- ---
44
3.7
44
3.4
44
3.1
44
2.9
44
2.6
850
--- ---
--- ---
--- ---
--- ---
44
3.5
44
3.2
44
2.9
44
2.7
44
2.5
875
--- ---
--- ---
44
3.5
44
3.3
44
3.0
44
2.8
44
2.5
47
3.4
900
--- ---
--- ---
44
3.3
44
3.1
44
2.8
44
2.6
47
3.5
48
3.6
925
44
3.7
44
3.2
44
2.9
44
2.7
44
2.5
48
3.7
48
3.4
950
44
3.5
44
3.0
44
2.8
44
2.6
47
3.4
48
3.5
48
3.3
975
44
3.3
44
2.8
44
2.6
47
3.5
48
3.7
48
3.4
49
3.6
1000
44
3.2
44
2.7
44
2.5
47
3.3
48
3.5
48
3.2
49
3.4
1050
44
2.9
44
2.5
48
3.7
48
3.4
49
3.7
--- ---
--- ---
--- ---
--- ---
1100
46
3.3
48
3.7
48
3.4
49
3.7
--- ---
--- ---
--- ---
--- ---
--- ---
--- ---
* When installing the 100,000 BTU furnace in downflow or horizontal positions, firing rate is reduced to 19,500 BTU/cell. Subtract 0.2” w.c
from the manifold pressures listed in table above for the correct manifold pressure.
Conversion: 1 in wc = 249 Pa
Bold--- indicates factory orifice size.
NOTE: Natural gas data is based on 0.60 specific gravity. For fuels with different specific gravity consult the National Fuel Gas Code ANSI Z223.1---2009/NFPA
54---2009 or National Standard of Canada, Natural Gas And Propane Installation Code CSA B149.1---10.
In the USA, derating of these furnaces at 2% (Natural Gas) and 4% (Propane Gas) has been tested and design---certified by CSA.
{
In Canada, the input rating must be derated 5% (Natural Gas) and 10% (Propane Gas) for altitudes of 2,000 to 4,500 (609.6 to 1371.6m) above sea level. Use
the 2001 to 3000 (609.9 to 914.4m) column in Tables 6 and 7.
Table 7 – LPG or Propane Gas Manifold Pressure (in wc)*
HEATING
VALUE
BTU/CU.
FT.
FURNACE
INPUT
BTU/
BURNER
MEAN ELEVATION FEET ABOVE SEA LEVEL Ft (M)
0 to 2000
2001 to 3000†
3001 to 4000
4001 to 5000
5001 to 6000
6001 to 7000
7001 to 8000
(0 to 610)
(610.1 to
914)†
(914.1 to
1219)
(1219.1 to
1524)
(1524.1 to
1829)
(1829.1 to
2134)
(2134.1 to
2438)
2500
20000
10.0
8.9
8.4
10.0
10.0
10.0
10.0
Orifice
Size
#55
#55
# 55
#56
#56
#56
#56
2500
19500‡
9.9
8.4
8.0
10.0
10.0
10.0
9.6
Orifice
Size
#55
#55
# 55
#56
#56
#56
#56
‡ Applies to 100,000 BTU models when installed in the downflow or horizontal applications
Conversion: 1 in wc = 249 Pa
NOTE: Propane data is based on 1.53 specific gravity. For fuels with different specific gravity consult the National Fuel Gas Code ANSI Z223.1---2009/NFPA
54---2009 or National Standard of Canada, Natural Gas and Propane Installation Code CSA B149.1---10.
In the USA, derating of these furnaces at 2% (Natural Gas) and 4% (Propane Gas) has been tested and design---certified by CSA.
{
In Canada, the input rating must be derated 5% (Natural Gas) and 10% (Propane Gas) for altitudes of 2,000 to 4,500 (609.6 to 1371.6m) above sea level. Use
the 2001 to 3000 (609.9 to 914.4m) column in Tables 6 and 7.
The burner orifice part nos. are as follows:
Orifice #41
333730--701
Orifice #42
333730--702
Orifice #43
333730--703
Orifice #44
333730--704
Orifice #45
333730--705
Orifice #46
333730--709
Orifice #47
333730--710
Orifice #48
333730--711
Orifice #49
333730--712
Orifice #54
333730--706
Orifice #55
333730--707
Orifice #56
333730--708
General Derating Rules
1. These furnaces may be used at full input rating when in-
stalled at altitudes up to 2,000′ (610 M). When installed
above 2,000′ (610 M), the input must be decreased 2%
(natural) or 4% (Propane) for each 1000′ (305 M) above
sea level in the USA. In Canada, the input rating must be
derated 5% (natural) or 10% (Propane) for each 1000′ (305
M) above sea level. See Table 6 or 7 for required high
altitude input rate.
2. For operation with natural gas at altitudes above 2,000′
(610 M), orifice change and/or manifold pressure adjust-
ments may be required for the gas supplied. First consult
359AA
V