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UH-PRC002-EN62
Mechanical
Specifications
Propeller Fan Gas Unit Heater
Centrifugal Fan Gas Unit
Heater
Indoor Gas Duct Furnace
General
Units are completely factory assembled,
piped, wired and test fired. All units are
AGA Certified and conform with the
latest ANSI Standards for safe and
efficient performance. Units are provided
with two-point suspension hangers on
propeller fan unit heaters and with four
point suspension hangers on centrifugal
fan unit heaters and duct furnaces. All
units are available for operation on either
natural or LP (propane) gas.
Casing
Casings are die-formed, 20-gauge
galvanized steel and finished in baked
enamel. The bottom panel is easily
removed to provide service access to the
burners, pilot and orifices. The pilot is
also accessible through a side panel
access plate.
On duct furnaces the high limit switch is
accessible through a side panel access.
Duct discharge flanges for simple
ductwork connection are provided.
All unit heaters are provided with
independently adjustable horizontal
louvers with stops to prevent total
closure.
Heat Exchanger
Standard heat exchanger construction
consists of seam welded 20-gauge
aluminized steel tubes and 18-gauge
aluminized steel headers.
The heat exchanger, burner and draft
hood assembly carry a non-prorated
warranty to be free from defective
material and workmanship for a period
of 10 years from date of manufacture,
excluding loss due to misuse,
negligence, or corrosion by chemicals
precipitated in the air. (Not available on
duct furnaces.)
Draft Diverter
Standard draft diverter construction is
corrosion resistant aluminized steel.
Burners
Burners are die-formed, corrosion
resistant aluminized steel, with stainless
steel port protectors. Port protectors
prevent scale or foreign matter from
obstructing the burner ports. Burners are
individually removable for ease of
inspection and servicing. Each burner is
provided with an individually adjustable,
manually rotated air shutter adjustment.
Air shutter adjustment is fixed on duct
furnaces when the side access burner
drawer is supplied.
Fans
Propeller fan blades are constructed of
aluminum with an aerodynamic contour.
All fans are dynamically balanced for
quiet, efficient operation and supplied
with a protective type fan guard. Rubber-
in-shear isolators provide isolation
between the fan/motor combination and
the unit heater casing.
Centrifugal fan is belt driven with
adjustable pitch motor sheave. Fan is
dynamically balanced for quiet
operation.
Motors
Standard motors are 115V, 60 Hz, single-
phase, open drip-proof with built-in
thermal overload protection. Optional
230/60/1 motors are available on all
units. Optional 208, 230, 460/60/3 motors
are available on 125 through 400 MBh
units.
Controls
A factory installed junction box is
provided for all power connections.
Standard units are provided with a
24-volt combination single-stage
automatic gas valve, including main
operating valve and pilot safety shutoff,
pressure regulator, manual main and
pilot shutoff valve, and adjustable pilot
valve. Gas valve is suitable to a
maximum inlet pressure of 0.5 psi (14-
inch W.C.) on natural gas. A 24V control
transformer, a spill (blocked vent) switch,
high limit and fan time delay relay
(optional on duct furnaces) are provided.
The fan time delay relay delays the fan
start until the heat exchanger reaches a
predetermined temperature. It also
allows the fan to operate after burner
shutdown, removing residual heat from
the heat exchanger.