Catalogue

UH-PRC002-EN 59
Mechanical Specifications
High Efficiency Propeller (model GH) and Centrifugal Fan Gas Unit Heaters (model GB)
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. All units are available for operation on either natural or LP
(liquid 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. All units 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 ten years from date of manufacture, excluding
loss due to misuse, negligence, or corrosion by chemicals precipitated in the air.
Burners
Burners are die-formed, corrosion resistant aluminized steel, with stainless steel port protectors.
Port protectors reduce 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.
Fans
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.
All Motors
Standard motors are 115V, 60 Hz, single phase, open drip-proof with built-in thermal overload
protection.
Optional Fan Unit Motors
All motors are 115V, 60 Hz, single-phase totally enclosed with built-in thermal overload protection
and permanently lubricated bearings.
Controls
A factory installed junction box is provided for all power connections. Standard units are provided
with a 24V combination single stage redundant gas valve, consisting of a combination pilot
solenoid valve, automatic electric gas valve, pilot filter, pressure regulator, pilot adjustment and
manual shutoff. A flue vent fan relay and combustion air proving switch is also provided as
standard. Standard equipment includes spark-ignited intermittent pilot system with electronic
flame supervision. A 24V control transformer, high limit and fan time delay relay 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.