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Sidewall
Inlet Vent and Exhaust-Air
Termination
with Exterior
Risers
18" MIn. for Cold C_3mates
(Subetalned Below 0 ° F)
S" Min.
Dimension "A" is touching or 2" maximum separation.
Rooftop Inlet Vent and Exhaust-
Air Termination
18" Min, for Cold Climates
-
_
1_<
(Substained
Below O"F)
8" Min. J
'
Inlet
j
20' Max. -
12" Min.
Grade or
2
Snow Level
25-22-43
Dimension"A" is touching or 2" maximumseparation.
5. Gas Supply and Piping
Fire and explosion hazard.
Natural Gas
1.
Supply pressure can be checked using the 1/8"(3.2mm )
NPT port on the supply side of the gas valve.
Models designated for Natural Gas are to be used
with Natural Gas Only, unless properly converted
to use with LP gas.
NOTE: The rating plate is stamped with the model number, gas
type and gas input rating. In addition, models manufactured for
sale in Canada have orifice size information stamped on the rat-
ing plate.
AlternateBTUH Input Ratings(USAOnly)
The input rating of these furnaces can be changed from the stan-
dard input rating to the alternate input rating shown in Table 6, by
changing the main burner orifices. Changing of burner orifices
MUST be done by a qualified service technician, See section on
changing orifices.
BTUH
Standard
Rating
50,000
75,000
100,000
125,000
Alternate Input Ratings, USA ONLY.
BTUH
Alternate
Rating
40,000
60,000
80,000
100,000
Natural
LP
Gas
Gas
Orifice
Orifice
#44
#55
#44
#55
#44
#55
#44
#55
Supply Pressure
Fire hazard.
2,
3.
Gas input to burners MUST NOT exceed the rated input
shown on rating plate.
Do NOT allow minimum gas supply pressureto vary down-
ward. Doing so will decrease input to furnace. Refer to
Table 7 for normal gas supply and manifold pressures.
Gas
Pressures
Below
2000
Ft.
Manifold
Pressure
Gas
Supply Pressure
Type
Recommended
Max.
Min.
Natural
7 inches
14 inches
4.5 inches
3.5 inches
LP
11 inches
14 inches
11 inches
10 inches
Important Notes
With Propane gas, the rated input is obtained when
the BTU content is 2,500 BTU per cubic foot and
manifold pressure set at 10" W.C.
If Propane gas has a different BTU content, orifices
MUST be changed by licensed Propane installer.
Measured input can NOT exceed rated input,
Combustion Air Box Cover MUST be removed when
adjusting manifold pressure.
Any major change in gas flow requires changing
burner orifice size.
ManifoldGas PressureAdjustment
NOTE: Gas supplypressure MUST bewithin minimum and maxi-
mum values listed on rating plate. Pressures are usually set by
gas suppliers.
Make adjustment to manifold pressure with burners operating
and combustionair box cover removed.
1.
Remove combustion air box cover.
Do NOT set input rating above that shown on
rating plate.
Failure to properly set input pressure can result in
property damage, personal injury and/or death.
2,
3
4.
Connect U-Tube manometer to the tapped opening on the
outlet side of gas valve. Use manometer with a O-min.f 2"
water column range.
Turn gas ON, fire the furnace and remove adjustment
screw cover on gas valve.
Turn counterclockwise to decrease pressure and clock-
wise to increase,
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