Manual 2100-486D
Page
24 of 37
20. STANDARD ORIFICE SIZING AND
HIGH ALTITUDE DERATE
This furnace is shipped with fixed gas orifices for use
with Natural Gas and sized for 1000 BTU/cubic foot
gas. Make sure actual gas input does not exceed rating
plate input. You may need to change orifices to get
correct gas input. Whether you do or not depends on
input, and your gas heat value at standard conditions
and elevation. Consult your local gas supplier for gas
heat value and any special derating requirements. See
Section 19 for more information.
At higher altitudes, the density of the air is reduced.
Therefore, for proper combustion, the quantity of gas
burned in the furnace must also be reduced. This is
called derating. This unit must be derated when
installed at altitudes greater than 6,000 feet above sea
level. A high altitude pressure switch must also be
installed for operation above 6,000 feet. High altitude
pressure switch kit number 8620-189 is designed for
this application.
TABLE 7
NATURAL GAS DERATE CAPACITIES
FOR ALL MODELS
d
e
t
a
R
F
W
t
u
p
n
I
a
e
S
l
e
v
e
L
0
0
0
,
1
0
0
0
,
2
0
0
0
,
3
0
0
0
,
4
0
0
0
,
5
0
0
0
,
6
0
0
0
,
7
0
0
0
,
8
0
0
0
,
9
0
0
0
,
0
1
0
0
0
,
1
4
0
0
0
,
5
4
0
0
5
,
0
4
0
0
0
,
5
4
4
0
2
,
9
3
0
6
5
,
3
4
8
0
9
,
7
3
0
2
1
,
2
4
2
1
6
,
6
3
0
8
6
,
0
4
0
4
6
,
5
3
0
0
6
,
9
3
2
9
9
,
4
3
0
8
8
,
8
3
2
8
1
,
4
3
0
8
9
,
7
3
6
9
6
,
3
3
0
4
4
,
7
3
8
4
0
,
3
3
0
2
7
,
6
3
3
4
6
,
2
3
0
7
2
,
6
3
6
7
0
,
2
3
0
4
6
,
5
3
0
0
0
,
1
6
0
0
0
,
8
6
0
5
7
,
0
6
0
0
5
,
7
6
6
0
8
,
8
5
0
4
3
,
5
6
2
6
8
,
6
5
0
8
1
,
3
6
8
1
9
,
4
5
0
2
0
,
1
6
0
6
4
,
3
5
0
0
4
,
9
5
8
8
4
,
2
5
0
2
3
,
8
5
3
7
2
,
1
5
0
7
9
,
6
5
4
4
5
,
0
5
0
6
1
,
6
5
2
7
5
,
9
4
0
8
0
,
5
5
5
6
9
,
8
4
5
0
4
,
4
5
4
1
1
,
8
4
0
6
4
,
3
5
0
0
0
,
5
7
0
0
0
,
1
8
0
0
0
,
5
7
0
0
0
,
1
8
0
0
6
,
2
7
8
0
4
,
8
7
0
0
2
,
0
7
6
1
8
,
5
7
0
0
8
,
7
6
4
2
2
,
3
7
0
0
0
,
6
6
0
8
2
,
1
7
0
0
8
,
4
6
4
8
9
,
9
6
0
0
3
,
3
6
4
6
3
,
8
6
0
0
4
,
2
6
2
9
3
,
7
6
0
0
2
,
1
6
6
9
0
,
6
6
0
5
4
,
0
6
6
8
2
,
5
6
0
0
4
,
9
5
2
5
1
,
4
6
0
0
0
,
0
9
0
0
0
,
0
0
1
0
0
0
,
0
9
0
0
0
,
0
0
1
0
2
1
,
7
8
0
0
8
,
6
9
0
4
2
,
4
8
0
0
6
,
3
9
0
6
3
,
1
8
0
0
4
,
0
9
0
0
2
,
9
7
0
0
0
,
8
8
0
6
7
,
7
7
0
0
4
,
6
8
0
6
9
,
5
7
0
0
4
,
4
8
0
8
8
,
4
7
0
0
2
,
3
8
0
4
4
,
3
7
0
0
6
,
1
8
0
4
5
,
2
7
0
0
6
,
0
8
0
8
2
,
1
7
0
0
2
,
9
7
0
0
0
,
3
1
1
0
0
0
,
5
2
1
0
0
5
,
2
1
1
0
0
0
,
5
2
1
0
0
9
,
8
0
1
0
0
0
,
1
2
1
0
0
3
,
5
0
1
0
0
0
,
7
1
1
0
0
7
,
1
0
1
0
0
0
,
3
1
1
0
0
0
,
9
9
0
0
0
,
0
1
1
0
0
2
,
7
9
0
0
0
,
8
0
1
0
5
9
,
4
9
0
0
5
,
5
0
1
0
0
6
,
3
9
0
0
0
,
4
0
1
0
0
8
,
1
9
0
0
0
,
2
0
1
5
7
6
,
0
9
0
5
7
,
0
0
1
0
0
1
,
9
8
0
0
0
,
9
9
It is the installer’s responsibility to see that the furnace
input rate is adjusted properly. Derating must be
achieved by reducing the size of the main burner
orifices. Derating the furnace by adjusting the manifold
pressure lower than the range specified in the Section
18, “Manifold Pressure Adjustment” is considered to be
an improper procedure.
Above 6,000 feet elevation orifice changes are required,
and capacity reductions are a function of altitude
impact and orifice change. Pressure switch change is
required above 6,000 feet elevation. For Natural Gas
see the Altitude Table 7 below and the Orifice Table 8
on following pages.
Summary of Contents for WF0501-A
Page 13: ...Manual 2100 486D Page 13 of 37 FIGURE 6 COMMON WALL MOUNTING INSTALLATIONS...
Page 19: ...Manual 2100 486D Page 19 of 37 FIGURE 11 LOW VOLTAGE WIRING...
Page 20: ...Manual 2100 486D Page 20 of 37 FIGURE 12 GAS PIPE CONNECTION...
Page 34: ...Manual 2100 486D Page 34 of 37 230 208 60 1...
Page 35: ...Manual 2100 486D Page 35 of 37 115 60 1...
