10
441 01 2610 00
CARBON MONOXIDE POISONING, FIRE AND
EXPLOSION HAZARD.
Failure to follow these instructions can result in
death, personal injury and/or property damage.
Models designated for Natural Gas are to be used
with Natural Gas ONLY, unless properly converted
to use with LP gas.
!
Gas Supply Requirements
·
Use only the Type of gas approved for this furnace. See rating
plate for approved gas type.
·
Gas input must not exceed the rated input shown on the rating
plate. Overfiring will result in failure of heat exchanger and
cause dangerous operation.
·
Do not allow minimum supply pressure to vary downward.
Doing so will decrease input to furnace. Refer to
Table 2
for
Gas supply and manifold pressures.
Table 2
Gas Pressures
Gas
T
Supply Pressure
Manifold
P
Type
Recommended
Max.
Min.
Pressure
Natural
7
²
14
²
4.5
²
3.5
²
Propane
11
²
14
²
11
²
10
²
Natural Gas Input Rating Check
The gas meter can be used to measure input to furnace. Rating is
based on a natural gas BTU content of 1,000 BTU’s per cubic foot.
Check with gas supplier for actual BTU content.
1. Turn
OFF
gas supply to all appliances other than furnace and
start furnace.
2. Time how many seconds it takes the smallest dial on the gas
meter to make one complete revolution. Refer to
Example
.
Note:
If meter uses a 2 cubic foot dial, divide results (se-
conds) by two.
Example
Natural Gas
BTU Content
No. of Seconds
Per Hour
Time Per Cubic
Foot in Seconds
BTU Per
Hour
1,000
3,600
48
75,000
1,000 x 3,600
¸
48 = 75,000 BTUH
3.
Relight all appliances and ensure all pilots are operating.
Orifice Sizing
NOTE:
Factory sized orifices for natural and LP gas are listed in
the furnace Technical Support manual.
Ensure furnace is equipped with the correct main burner orifices.
Refer to
Table 3
for correct orifice size for a given heating value
and specific gravity for natural and propane gas. Note that this
chart is
ONLY
for installations
below
2000
¢
in altitude.
Table 3
Orifice Sizes (below 2000
¢
)
Gas
Type
Manifold
Pressure
Specific
Gravity
Heating Value
(BTU per
Cubic Ft.)
Orifice Size
(Drill #)
Natural
3 5
²
w c
800
40
3.5
²
w.c.
0 9kP
0 6
900
41
0.9kPa
w c
0.6
1000
42
w.c.
1100
43
Propane
10
²
w.c.
2.5kPa
w.c.
1.53
2500
54
Operation Above 2000
¢
Altitude
FIRE, EXPLOSION, CARBON MONOXIDE POISON-
ING HAZARD.
This conversion shall be done by a qualified ser-
vice agency in accordance with the Manufactur-
er’s instructions and all applicable codes and re-
quirements, or in the absence of local codes, the
applicable national codes.
Failure to follow these instructions exactly can re-
sult in death, personal injury and/or property dam-
age.
!
These units may be used at full input rating when installed at alti-
tudes up to 2000
¢
. When installed above 2000
¢
, the input must be
decreased 2%(natural) or 4%(LP) for each 1000
¢
above sea level.
This may be accomplished by a simple adjustment of manifold
pressure or an orifice change, or a combination of a pressure ad-
justment and an orifice change. The changes required depend on
the installation altitude and the heating value of the fuel.
Table 4
&
Table 5
show the proper furnace manifold pressure and gas ori-
fice size to achieve proper performance based on elevation above
sea level for both natural gas and propane.
To use the natural gas table, first consult your local gas utility for
the heating value of the gas supply. Select the heating value on the
vertical border and follow across the table until the appropriate
elevation for the installation is reached. The first value in the box at
the intersection of the heating value and elevation will be the man-
ifold pressure required. If a gas orifice change is also required, the
box is shaded. The required orifice size is shown at the bottom of
the table.
Sea Level
High Altitude Input Rate = Nameplate x (Multiplier)
Input Rate
Elevation
High Altitude Multiplier
Elevation
Natural
LP Gas
2000
¢
- 2999
¢
0.96
0.92
3000
¢
- 3999
¢
0.94
0.88
4000
¢
- 4999
¢
0.92
0.84
5000
¢
- 5999
¢
0.90
0.80
6000
¢
- 6999
¢
0.88
0.76
7000
¢
- 7999
¢
0.86
0.72
