Form I-RDF, P/N 148384 (Rev 1), Page 13
clockwise until the filter light is energized or the screw is bottomed out. At
that point, adjust the set screw three full turns counterclockwise or until
the screw is top ended. At that setpoint, the filter light will be activated at
approximately 50% filter blockage.
Discharge Sensor (Maxitrol) for Gas Control Options
AG30, AG31, AG32, AG33, AG47, AG48
A discharge sensor may be shipped separately for field installation. Attach the
discharge sensor and mixing tube in the ductwork about six feet (1.8 M) from
the discharge opening of the system.
The sensor housing is not waterproof. If the installation is outdoors, field-fab-
ricate a waterproof protective enclosure for the discharge sensor, being careful
not to affect its air temperature sensing capability. If the ductwork is insulated,
be sure that the sensing bulb is mounted so that it is fully exposed to the air-
stream being sensed.
Refer to the wiring diagram and connect the sensor to the terminal strip in the
blower section electrical box. Use shielded wire to alleviate any electrical in-
terference that may cause an erroneous discharge temperature reading.
Outside Air Cutoff Control (Option BN2)
After sensing pilot flame, the burner ignites at its lowest input rate. The "amount
of heat" required to reach the desired discharge temperature also depends on
the temperature of the incoming outside air. The outside air cutoff (high ambi-
ent control) is factory set at 60°F (adjustable 25-250°F). The burner reacts
differently depending on the entering air temperature and the setting on this
control. The burner --
• may not ignite (pilot valve will not open);
If the actual temperature of the outside air is above the setpoint on the
outside air control, the burner will not ignite.
• may modulate to satisfy discharge setting;
• would shutdown completely only on Option BN2 control, once burner has
been fired; or
Modulating operation will depend on the temperature rise between the
outside air and the discharge air setting.
• may remain on continuous low fire.
If the outside air control is set too high, the burner will continuously burn
on low fire as long as the control switch is set to "winter".
When the outside air control is set properly for the climate, the system blower
will continue to provide the required makeup air (ventilation) at the ambient
outdoor temperature (burner not operating) even when the control switch is set
to "winter".
If at startup, it is determined that the outside air cutoff control is not set prop-
erly, change the setting on the control (located in the main electrical compart-
ment) and test for proper operation.
Discharge Temperature Low Limit (Option BE2)
If the system has an optional low limit switch for discharge temperature
(freezestat), the control is in the blower section electrical box. The sensing
bulb must be field-mounted in the blower discharge duct connector. Uncoil the
control and extend the bulb to the blower discharge, being careful to not inter-
fere with any mechanical parts. Use the bulb holder provided and mount the
sensor according to the manufacturer's instructions.
Door Switch (Option BX1)
If the system is to be used as an overhead door heater, an optional door switch
(Option BX1) must be installed. The function of the switch is to energize and
FIGURE 12 - Discharge
Sensor and Mixing Tube
FIGURE 13 - Control used
for Outside Air Cutoff and
Discharge Temperature
Low Limit (Freezestat)
FIGURE 14
- Optional
Door Switch
