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Section 11:
Gas Heater Packages:
11.1 Principle of Operation
The gas furnace is an 80% efficient, self-contained duct
furnace that can burn natural gas or LPG. It is comprised of:
• Manifold: Includes combination gas valve
incorporating redundant safety shut-off valve, manual
shut-off and gas regulator.
• Burners: Inshot gas burners with direct spark ignition
and remote flame sensor to ensure carryover across
all burners.
• Heat exchanger: Serpentine heat exchanger
constructed of 409 stainless steel.
11.2 Gas Piping and Pressure
All gas piping to the unit must comply with:
United States: Refer to NFPA 54/ANSI Z223.1-latest
revision, National Fuel Gas Code.
Canada: Refer to CSA B149.1 - latest revision, Natural Gas
and Propane Installation Code.
The gas furnace is equipped to handle a maximum gas
supply pressure of 13.5” w.c. (33.5 mbar). When gas
supply exceeds this maximum gas pressure, an additional
high gas pressure gas regulator will be required by others
to insure that the correct gas pressure is supplied to the
combination gas valve.
The gas supply is normally piped through an outside
unit cabinet wall. If through the curb gas connection is
required, the connection is made as necessary in the
furnace vestibule compartment. A manual shut-off valve
must be provided by others. Gas piping and the manual
shut off valve must conform to best building practices and
local codes. Support piping with hangers and not with
the furnace itself. Units with multiple furnaces require
individual gas connections.
Two 1/8” NPT pressure test ports for measuring manifold
inlet pressure are located on the gas valve.
DANGER
ELECTRICAL SHOCK HAZARD
Disconnect electric before service.
More than one disconnect switch
may be required to disconnect
electric from equipment.
Equipment must always be
properly grounded.
SEVERE INJURY HAZARD
Do not enter equipment while in
operation. Equipment may start
automatically. Do not operate with
access doors open. Installation,
operation, and maintenance
must be performed by a trained
technician only.
BURN HAZARD
Allow equipment to cool before
service. Internal components of
equipment may still be hot after
operation.
CUT/PINCH HAZARD
Wear protective gear during
installation, operation, or
maintenance. Edges are sharp.
Failure to follow these instructions can result in
death, electrical shock, or injury.
Failure to follow these instructions can result in
death, injury, or property damage.
FIRE
HAZARD
WARNING
EXPLOSION
HAZARD
CARBON
MONOXIDE
HAZARD
Minimum
Heat
Input:
Gas NPT
Connection
Minimum
Inlet Gas
Pressure -
NG
Minimum
Inlet Gas
Pressure -
LPG
BTUH
in.
in w.c.
in w.c.
< 400,000
0.75
5.0
11.0
> 400,000
1.00
6.0
12.0
Table 2: Manifold Size and
Minimum Pressure
PR Series Installation, Operation, and Maintenance Manual
