Catalogue

66 UH-PRC002-EN
Mechanical Specifications
Units are provided with two-point suspension hangers on propeller fan unit heaters and with four-
point suspension hangers on centrifugal fan unit heaters. Units are available for operation on either
natural or LP (propane) gas. Standard terms and conditions apply.
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 orifice. All units 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.
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
individually removable for ease of inspection and servicing. Each burner is provided with an
individually adjustable, manually rotated air shutter adjustment.
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.
Electronic Modulating 4–20 mA/0–10 Vdc Input
Provides modulated heat output. Ignition is at full fire (100 percent input), and modulates the gas
input from 100 percent to 40 percent rated input.
The modulating gas valve shall operate in response to a 4–20 mA or a 0–10 Vdc input from an
external DDC control.
Flue Vent Fan
Flue vent fan provides power venting. Provided factory assembled to a sealed flue collection
chamber. The flue vent fan is activated in response to a low voltage (24V) single-stage thermostat.
Note: The thermostat is not included with the gas control option.
A combustion air pressure switch is provided as standard to verify proper powered vent flow prior
to allowing the gas valve to operate.
Factory-Installed Options
Two-Stage Gas Valve
Provides two stages of heat. Ignition is at low fire (50 percent of the furnace’s rated input). Requires
the use of a two-stage thermostat.
Heat Exchanger Options
Type 409 Stainless Steel
Heat exchanger tubes and headers are seam welded 20-gauge Type 409 stainless steel.