Sterling MS - Manual (Page 13)

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DUCT CONNECTIONS
All ductwork must be properly supported so that no strain
is put on the unit. Do not alter or bend the discharge duct
fl anges supplied on your make-up air unit.
Duct connections must have a removable access panel
in the duct which is connected to a duct furnace. The
duct openings shall be accessible when the unit is
installed in service, and shall be of such size that smoke
or refl ected light may be observed inside the casing to
indicate the presence of leaks in the heating element.
The covers for the panels shall be attached in such a
manner as to prevent leaks. Ducts (or optional outside air
hoods) exposed to the outdoors must be insulated and
sealed to prevent water from entering either the unit or
building through the duct.
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" N.P.T. plugged tapping,
accessible for test gauge connection, must be installed
immediately upstream of the unit gas supply connection.
The open end of piping systems being
purged shall not discharge into areas where there are
sources of ignition or into confi ned spaces UNLESS
precautions are taken as follows: (1) By ventilation of
the space, (2) control of purging rate, (3) elimination
of all hazardous conditions. All precautions must be
taken to perform this operation in a safe manner!
†† For complete Gas Piping installation, see the
Separated Combustion Indoor Gas-Fired Duct
Furnace Installation and Service Manual.
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 Separated Combustion
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 qualifi ed 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.