Reznor UEZ - Vent System and Drain Checks

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UEZ-IOM (07-23) 1034347-I
MAINTENANCE—CONTINUED
Maintenance Procedures—Continued
Vent Temperature Limit Switch Maintenance
The vent temperature limit switch (see Figure 36) 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 temperature limit switch could be caused by one
or more of the following:
• Manifold gas pressure too high
• Heat content of fuel being burned is too high
• Reduced circulating airflow due to dirty and/or plugged air moving components
• Excess dirt on heat exchanger(s)
• Failed heat exchanger(s)
After the cause is determined and corrected, press the red button on the switch to reset it.
Disconnect Switch Replacement
The disconnect switch (see Figure 36) 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 the electrical box cover.
Flame Rollout Switch Maintenance (Unit Sizes 055–110)
• The cause of a flame rollout switch (see Figure 27 for location) activating must be determined. Activation of the
manually-reset flame rollout switch could be caused by one or more of the following:
a. Restricted or plugged heat exchanger
b. Too much building exhaust
c. Manifold gas pressure too high
d. Restricted combustion air inlet or exhaust outlet in combination with defective pressure switch
e. Electrical power interruption during operation
f. Unit being operated with line voltage disconnect (24V thermostat is required)
• If a flame rollout switch trips, inspect the burner/control compartment for signs of excessive heat and burned wiring.
If there is damage to the control compartment, repairs must be made before resetting the switch.
• If the compartment appears normal, reset by depressing the red button on the switch (15– 20 minutes are required
for the switch to cool sufficiently before resetting). A distinct click will be felt when the switch resets. Operate the
furnace. If the flame rollout switch trips again, determine and correct the cause before resetting the switch.
• If it is determined that the flame rollout switch needs replacing, use only the factory-authorized replacement part
that is designed for that size of heater. The disconnect switch is located in the sealed electrical box inside the
control compartment with the toggle on the rear of the heater.
Vent or Vent/Combustion Air System Maintenance
Check the complete system at least once a year. Inspection should include all joints, seams, concentric adapter
box, inlet air guard or inlet air cap, and the vent terminal cap. Clean all openings and replace any defective parts.
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 may have accumulated. Check to be ensure that the piping to the sanitary drain has
not been damaged. Check the sanitary drain to verify that it flows freely.