Sterling ME - Manual (Page 8)

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If a single, double or triple duct furnace only unit is
connected to a return air duct, or any other inlet air
restriction, the appliance shall be installed on the positive
pressure side of the air circulating blower.
When connecting return air duct to Standard or High
CFM cabinets, attach duct to return air opening fl ange
when no dampers are used. Otherwise, if dampers are
used, attach return air duct around collar at bottom of
damper assembly. Also refer to the Dimensional Data
section of this manual, Submittal Data Sheets and Indoor
Duct Furnace Manual specifi ed for your unit.
GAS PIPING††
All gas piping must be installed in accordance with local
codes. It is required that a ground union be installed
adjacent to the gas valve of each duct furnace, and
a ground union be installed just external of each duct
furnace for unit servicing. On vertical runs, a drip leg
should be provided upstream of any control manifold. A
gas shutoff valve should be, or may be required by local
codes, installed upstream of the external ground union
for each duct furnace. A 1/8 inch N.P.T. plugged tapping,
accessible for test gauge connection, must be installed
immediately upstream of the unit gas supply connection.
†† For complete Gas Piping installation, see the
Indoor Gas-Fired Duct Furnace Installation and
Service Manual.
Gas piping must be installed to allow for removal of
burner drawer for unit maintenance. Refer to Figure 5,
and the maintenance section.
To avoid equipment damage or
possible personal injury, do not connect gas
piping to this unit until a supply line pressure/
leak test has been completed. Connecting the
unit before completing the pressure/leak test may
damage the unit gas valve and result in a fi re hazard.
Do not rely on a gas shutoff valve to
isolate the unit while conducting gas pressure/leak
tests. These valves may not be completely shutoff,
exposing the unit gas valve to excessive pressure,
resulting in damage.
Do not over-tighten the inlet gas piping
at unit gas valve or stresses that could crack the
valve may result.
Never use an open fl ame to detect
gas leaks. Explosive conditions may exist which
would result in personal injury or death.
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 shutoff valve
during any pressure testing of the gas supply 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 Indoor Gas-Fired Duct
Furnace Installation and Service Manual.
For additional piping information, refer to the National
Fuel Gas Code Z233.1 (latest edition).
NOTICE: If the gas duct furnace is to be fi red with LP gas,
consult local LP gas dealer for piping size information.
NOTICE: 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)*
Mechanical: On units equipped with mechanical modulating
gas control, the temperature sensing bulb for the gas valve
must be fi eld installed in the supply plenum. Carefully uncoil
the capillary tubing to prevent kinking or sharp bends.
Do not bend the capillary tubing within
1 /
2
" (12.7mm) of the connection to the bulb or the valve.
Repeated bending may cause the tubing to leak or break.
Center and fasten the temperature sensing bulb in the
supply duct at least 6 inches beyond the last duct furnace
section. See Figure 7.
Figure 7
AIR FLOW
Duct
Furnace
D8772
6"
(152)
Min.
Supply Duct
Temperature Sensing
Bulb Mounted To "L"
Bracket Centered In
Supply Duct.
D8772