Sterling RT - Manual (Page 10)

10
When connecting supply air duct to Supply Plenum, attach
duct to supply air opening fl ange when no dampers are
used. Otherwise, if dampers are used, attach supply air
duct around collar at bottom of damper assembly.
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 Outdoor
Rooftop Gas-Fired Duct Furnace Installation and
Service Manual, and if applicable the Factory Installed
Options Manual.
It is recommended that the gas piping not be installed
through the bottom of the duct furnace bottom panel. If
piping must penetrate the duct furnace bottom panel, it
must be sealed to prevent water leakage.
Gas piping must be installed to allow for removal of
burner drawer for unit maintenance.
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.
VENTING†
All venting installations shall be in accordance with the
latest edition of Part 7, “Venting of Equipment”, of the
National Fuel Gas Code, ANSI Z223.1 or applicable
provisions of local building codes.
The venting is an integral part of
the unit and must not be altered in the fi eld.
The Natural Vented units are equipped with a vent
cap which is designed for natural draft venting. Air for
combustion enters the base of the vent cap through a
protective grill and products of combustion are discharged
at the upper section of the vent cap. † This vent cap is
shipped in a separate carton and should be installed
per the Venting section of the Outdoor Rooftop Gas-
Fired Duct Furnace Installation and Service Manual.
The Power Vented unit has a induced draft venting system.
The combustion air inlet and products of combustion
discharge louvers are located in the upper section of the
Duct Furnace side access panel. Never locate these
units in an area where the fl ue products discharge
outlet may be directed at any fresh air vents. See the
Outdoor Rooftop Gas-Fired Duct Furnace Installation
and Service Manual for installation and servicing
requirements.
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 flanges supplied on your furnace/air
handler.
Ducts connected to units which do not have either a blower
section or a supply plenum 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 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 Submittal Data Sheets
specifi ed for your unit.