User Manual

5
6-189.14
All units include the standard (STD) features, and may include
the optional (OPT) features shown.
j Gas Valve (See Table 18.2)
a) Single Stage Gas Valve - (STD)
The main gas valve is factory installed on the unit heater
gas train. The main gas valve provides the pilot, regulator,
main gas, and manual shutoff functions.
b) Two Stage Gas Valve - (OPT)
The two-stage gas valve is factory installed on the unit
heater gas train. The two stage gas valve provides the
pilot, regulator, main gas (100% and 50% fire), and manual
shutoff functions. See the supplier literature included with
the unit.
k Ignition controller - (STD)
The ignition controller is factory installed on the back of the
unit heater with the spark igniter and sensor located on the
burner. For both natural and propane gas units, the ignition
controller is 100% shut-off with continuous retry. On a call for
heat, the system will attempt to light the pilot for 70 seconds.
If the pilot is not sensed for any reason, the ignition control
will wait for approximately six minutes with the combination
gas control closed and no spark. After six minutes, the cycle
will begin again. After three cycles, some ignition controllers
lockout for approximately one hour before the cycle begins
again. This will continue indefinitely until the pilot flame is
sensed or power is interrupted to the system.
l Time Delay Relay - (STD)
The time delay relay is factory installed in electrical junction
box. The time delay relay allows the gas controls to operate
for approximately 30 to 90 seconds before the blower starts.
This allows the heat exchanger a warm up period so that the
initial delivered air is not cool. The time delay relay also
keeps the motor running for approximately 30 - 90 seconds
after the call for heat has been satisfied to remove the
residual heat from the heat exchanger.
m Low Voltage Terminal Board - (STD)
The low voltage terminal board is located in electrical junction
box. The terminal board is labeled to match the electrical
wiring diagram provided with the unit.
n Control Step Down Transformer - (STD)
The control step down transformer is located in the electrical
junction box. The transformer is used to step down the supply
power (115V, 208V, 230V, 460V, 575V) to 24V for the gas
controls, fan delay relay, field supplied motor starter, etc.
To determine the control transformer supplied as well as any
accessory/field supplied transformers required, refer to
Table 18.1
o Blower Motor - (OPT)
The blower motor is factory installed on the blower housing.
The blower motor can be provided in a variety of supply
voltages and motor horsepowers. The blower motor is
supplied with an adjustable sheave that can be used to
increase/decrease the blower RPM.
p High Limit Switch - (STD)
The automatic reset high limit switch is factory installed on the
side of the unit heater. If the limit temperature is exceeded,
the gas controls are de-energized until the switch is cooled.
q Pressure Switch (STD)
A automatic reset vent pressure switch is supplied on all
power vented unit heaters to prevent operation of the main
burner in the event there is restricted venting of flue products.
This restriction may occur due to an improper vent diameter,
long vent runs, un-approved vent terminal, high winds, high
negative pressure within space, etc. After the cause of the
restriction has been corrected, the pressure switch will reset
automatically.
r Power Exhauster (STD)
All power vented unit heaters are supplied with a round vent
pipe connection. The power exhauster may be rotated 180° to
allow for various venting directions.
s Finger Proof Fan Guard (OPT)
Propeller units may be equipped with an optional finger proof
fan guard for added protection. The finger proof fan guard is
installed at the factory in place of the standard fan guard.
Standard fan guard is shown.
Figure 5.1 - Factory Mounted Standard and Optional Features (Models PDP/BDP)
DESIGN FEATURES - MODELS PDP/BDP
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