Gas Supplyand Piping - ICP NTC7/GNL Series Installation Instructions Manual

6. Gas Supplyand Pipin9
Fire and explosion hazard.
Natural Gas
Models designated for Natural Gas are to be used
with Natural Gas ONLY.
Failure to follow these instructions can result in
property damage, personal injury and/or death.
Gas Supply Requirements
Heating Value
Gas Manifold Specific (BTU per
Type Pressure Gravity Cubic Ft.)
Natural
3.5" w.c.
0.9kPa
W.C.
0.6
800
900
1000
1100
10" w.c.
Propane 2.5kPa 1.53 2500
W.C.
Orifice Size
(Drill #)
40
41
42
43
54
• Use only the Type of gas approved for this furnace. See rat-
ing plate for approved gas type.
• Gas input must not exceed the rated input shown on the rat-
ing 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.
IGas
P ressures
Gas
Type
Min.
Natural 4.5" 3.5"
(1.1 kPa) (0.9 kPa)
Propane 11" 10"
(2.7 kPa) (2.5 kPa)
Supply Pressure
Recommended Max.
7" 14"
(1.7 kPa) (3.5 kPa)
11" 14"
(2.7 kPa) (3.5 kPa)
Manifold
Pressure
Operation Above 2000 Feet Altitude
Fire, Explosion, Poison carbon monoxide gas
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
result in property damage, personal injury and/or
death.
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 No. of Seconds Time Per Cubic BTU Per
BTU Content Per Hour Foot in Seconds 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.
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 4% for each 1000' above sea level. This may be ac-
complished by a simple adjustment of manifold pressure or an ori-
fice change, or a combination of a pressure adjustment 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 orifice 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
manifold pressure required. If a gas orifice change is also re-
quired, 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
High Altitude
Elevation Multiplier
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