Reznor MAPS III, Cabinet D RECB Users Manual - Manual (Page 21)

Form O-MAPSIII Cabinet D, P/N 222918R9, Page 21
CAUTION: Touching the operating hot gas bypass valve can
cause a burn. Use caution when checking and adjusting the
valve. See Hazard Levels, page 2.
If a hot gas bypass valve needs to be replaced, use only a factory-authorized replace-
ment for R410-A refrigerant. All refrigerant service should be done by a qualified
R410-A service technician.
3.9.6 Modulating
Reheat, Option AUR1
Function: Units with modulating reheat control (Option AUR1) have a temperature
control board with a potentiometer, an air temperature sensor, and an electric dis-
charge bypass valve. When reheat is active, the sensor monitors the air temperature
as it leaves the reheat coil. Based on the potentiometer setpoint, the board will open
or close the bypass valve. If the leaving air temperature is higher than the setpoint, the
board will open the valve adding refrigerant hot gas to the refrigerant liquid before it
enters the pre-cool coil. This reduces the coil's ability to absorb the heat, and thus, the
reheat coil's ability to reject. If the leaving air temperature is lower than the setpoint,
the opposite occurs.
Service: Check the wiring connections at the board. The board is polarity sensitive;
positive connects to terminal 1 and negative to terminal 2.
The valve may be tested by measuring the resistance of the leads. Remove the power
and the leads from the board before testing. Resistance between the black and white
leads should be about 75 Ohms. Resistance between the green and red leads should
be within 5% of the white and black.
Use only factory-authorized replacement parts.
4.0 Gas Heat
Section
Maintenance -
Models RDCB
and RDDB
This gas heater will operate with a minimum of maintenance. To ensure long life and
satisfactory performance, a heater that is operated under normal conditions should be
inspected and cleaned at the start of each heating season. If the heater is operating in
an area where an unusual amount of dust or soot or other impurities are present in the
air, more frequent maintenance is recommended.
When any service is completed, be careful to reassemble correctly to ensure that no
unsafe conditions are created. When re-lighting, always follow the lighting instructions
on the furnace.
WARNING
Turn off the power before performing maintenance procedures.
Lock disconnect switch in OFF position. When you turn off the
power supply, turn off the gas at the external manual valve. See
Hazard Levels, page 2.
This gas heat section is equipped with a
T
CORE
2
® style heat exchanger and burner.
Inspect the gas heat section annually to determine if cleaning is necessary. If there is
an accumulation of dirt, dust, and/or lint, clean the compartment.
CAUTION: Use of eye protection is recommended.
4.1.1 Instructions for Inspecting/Cleaning a Heat Exchanger
1. Shut off the gas supply.
2. Turn off electric power supply.
3. Open the gas heat section access door and the blower section door.
4. Remove the venter motor and wheel assembly. (See FIGURES 7 and 8.)
a) At the control board, locate the two or three venter motor wires. Mark and
disconnect the wires.
4.1 Heat Exchanger,
Burner,
and Venter
Maintenance