Sterling RT - Manual (Page 4)

4
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 ventcap 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 grills are located in the upper section of the
Duct Furnace side access panel.
A pilot burner plate is provided in the Duct Furnace for
access to the pilot burner and ignition system without
removing the burner drawer. Clearance between the
external unit and any obstruction must be suffi cient for
proper servicing of pull out burner drawer. See Figure 2
& 3 for this clearance.
These units are certifi ed for operation on either natural
or propane gases. If a unit is to be installed at an altitude
exceeding 2000 feet (610 m) above sea level, derate the
unit input of each duct furnace by 4% for each 1000 feet
(305 m) above sea level. Special main burner gas orifi ces
are required for installations above 2000 feet (610 m).
In Canada, if unit is to be installed at altitudes of 2000
feet (610 m) to 4500 feet (1372 m), each duct furnace
must have the main burners re-orifi ced to give 90% of the
normal altitude input rating.
If the unit was ordered from the factory for high altitude
operation, confi rm input rating. See Gas Input Adjustment.
RIGGING
Rig unit using either belt or cable slings. Use spreader
bars to protect the top of the unit when it is lifted. See
Figure 1.
On units with a total length of less than 104 inch
(2642 mm), excluding evaporative cooler, two holes are
provided in the base rail on each side of the unit. Slide
pipes beneath the unit through these holes and attach
rigging to pipes for lifting the unit.
On units with a total length of a 104 inch (2642 mm) or
greater, excluding evaporative cooler, lifting lugs attached
to the base rail are provided. Attach rigging to lugs for
lifting the unit. For distance between lifting lugs and total
unit lengths, refer to original Submittal Sheets supplied
specifi ed for the unit. Also see Center of Gravity and
Weights Sections in this manual.
Figure 1
COMBUSTION AIR CONSIDERATIONS
The presence of chlorine vapors or other corrosive
vapors in the combustion air supply for gas-fi red heating
equipment presents a potential corrosive hazard.
Chlorine will, when exposed to fl ame, precipitate from
the compound (usually freon or degreaser vapors) and
go into solution with any condensation that is present
in the heat exchanger or associated parts. The result
is hydrochloric acid which will readily attack all metals,
including 300 grade stainless steel. Care should be taken
to separate these vapors from the combustion process.
This may be done by wise location of the unit with regard
to exhausters or prevailing wind direction.