Reznor UEAS Unit Installation Manual - Manual (Page 40)

12.2 Maintenance Procedures (cont’d)
For location of controls,
see FIGURE 28, page 37.
12.2.12 Vent Temperature Limit Switch
The vent temperature limit switch is located on the discharge of the combustion
air blower (venter) and its purpose is to prevent the vent gas temperature from
exceeding a temperature that will harm the PVC vent pipe. If the vent temperature
limit switch is activated, the cause must be determined and corrected before the
heater is placed back into operation. Activation of the manually reset vent tempera-
ture limit switch could be caused by one or more of the following:
• Manifold gas pressure too high
• The heat content of the fuel being burned is too high
• Reduced circulating airflow due to dirty an/or plugged air moving
components
• Excess dirt on the heat exchangers
• Failed heat exchanger(s)
After the cause is determined and corrected, depress the red button on the switch
to reset it.
12.2.13 Disconnect Switch
The disconnect switch is located in the sealed electrical box inside the control
compartment with the toggle on the rear of the heater.
If it is determined that the disconnect switch needs replacing, use only the factory-
authorized replacement part that is designed for the heater. Always replace electri-
cal box cover.
Disconnect
Switch
Vent Temperature
Limit Switch
12.2.14 Vent/Combustion
Air System
Check the complete system at least once a year. Inspection should include all
joints, seams, concentric adapter box, inlet air guard or cap, and the vent terminal
cap. Clean openings. Replace any defective parts.
12.2.15 Condensate
Drain System
Check the condensate disposal system annually. Remove the condensate traps
and flush them with clear tap water to remove any sediment that my have accumu-
lated. Check to be certain the piping to the sanitary drain has not been damaged.
Check the sanitary drain to verify that it flows freely.
12.0 Maintenance
and Service
(cont’d)
12.3 Troubleshooting
The integrated circuit board monitors the operation of the heater and includes two
LED signal lights that indicate normal operation and various abnormal conditions.
If the heater fails to operate properly, check this signal to determine the cause
and/or to eliminate certain causes. LED is visible through the door. See operating
sequence in Paragraph 10.
Do not attempt to repair the DSI integrated control module (circuit board); the only
field replaceable component is the fuse.
Check the Lights on the DSI Integrated Control Module (Circuit
Board)
IMPORTANT: When using
a multimeter to troubleshoot
the 24 volt circuit, place the
meter’s test leads into the 5 or
9 pin connectors located on the
ignition control. Do not remove
connectors or terminals from the
electrical components. Doing
so can result in misinterpreted
readings due to the ignition
control board’s fault mode
monitoring circuits.
Control Status - Green LED Codes
Steady ON.....Normal Operation, No call for heat
Fast Flash......Normal Operation, Call for heat
1 Flash...........System Lockout, Failed to detect or sustain flame
2 Flashes.......Pressure Switch Did Not Close within 30 Seconds of Venter Motor
3 Flashes.......High Limit or Vent Temperature Limit Open
4 Flashes.......Pressure Switch is Closed Before Venter Motor is Energized
Steady OFF....Blown fuse, No Power, or Defective Board
Flame Status - Yellow LED Codes
Steady ON.....Flame is sensed
Slow Flash.....Weak flame (current below 1.0 microamps ± 50%)
Fast Flash.....Undesired Flame (valve open and no call for heat)
Form I-UEAS, Page 40