Modulating Gas Control - Trane GRAA Installation Operation & Maintenance

CAUTION : Do not over-tighten the inlet gas pip-
ing at unit gas valve or stresses that could crack
the valve may result.
The gas line should be supported so that no strain is
placed on the unit. Pipe compounds which are not
soluble to liquid petroleum gases must be used on
threaded joints.
The appliance and its individual shutoff valve must
be disconnected from the gas supply piping system
during any pressure testing of that system at test
pressures in excess of 1/2 psig (3.5 kPa).
The appliance must be isolated from the gas supply
piping system by closing the individual manual shut-
off valve during any pressure testing of the gas sup-
ply piping system at test pressures equal to or less
than 1/2 psig (3.5 kPa).
;
For additional gas piping information, including pipe
sizing and drip leg installation, refer to Outdoor
Rooftop Gas-Fired Duct Furnace Installation and
Service Manual.
For additional piping information, refer to the
National Fuel Gas Code Z233.1 (latest edition).
NOTE : If the gas duct furnace is to be fired with
LP gas , consult local LP gas dealer for pip i ng
size information .
NOTE : UNIT INSTALLATION FOR USE WITH
PROPANE (BOTTLED) GAS MUST BE MADE BY
A QUALIFIED LP GAS DEALER OR INSTALLER .
HE WILL INSURE PROPER JOINT COMPOUNDS
ARE USED FOR MAKING PIPE CONNECTIONS ;
THAT AIR IS PURGED FROM LINES ; THAT A
THOROUGH TEST
IS MADE FOR LEAKS
BEFORE OPERATING THE UNIT; AND THAT IT IS
PROPERLY CONNECTED TO PROPANE GAS
SUPPLY SYSTEM .
Before any connection is made to an existing line
supplying other gas appliances, contact the local gas
company to make certain that the existing line is of
adequate size to handle the combined load.
Check all connections for leaks with soap solution.
MODULATING GAS CONTROL (OPTIONAL)*
Mechanica l : On units equipped with mechanical
modulating gas control, the temperature sensing
bulb for the gas valve must be field installed in the
supply plenum. Carefully uncoil the capillary tubing
to prevent kinking or sharp bends.
CAUTION: Do not bend the capillary tubing with-
in 1/2" (12.7 mm) of the connection to the bulb or
the valve. Repeated bending may cause the tub-
ing to leak or break.
Center and fasten the temperature sensing bulb in
the supply duct at least 2 inches below the last duct
furnace section. See Figure 5.
Figure 5
Electronic : On units (natural gas only) equipped
with electronic modulating control, follow control
manufacturer's installation instructions for sensing of
outlet air temperature.
* Also refer to the Outdoor Duct Furnace
Installation Manual supplied with your unit.
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Caution: Do not rely on a gas shutoff valve to iso-
late the unit while conducting gas pressure/leak
tests. These valves may not be completely shut-
off, exposing the unit gas valve to excessive
pressure, resulting in damage.