Reznor UDAP 250000 BTU User Manual
10.0 Maintenance
and Service
(cont’d)
10.2 Maintenance
Procedures
(cont’d)
FIGURE 24 - Pressure
Tap for Checking Gas
Flow Shuto
10.2.7 Operating Gas Valve (cont’d)
Single-Stage Valves
1/8ʺ Outlet
Pressure Tap
1/8ʺ Outlet
Pressure Tap
Two-Stage Valve
1/8ʺ Outlet
Pressure Tap
NOTE: Operational
pressure settings and
instructions for checking
pressure settings are in
Paragraph 6.1.
10.2.8 Combustion Air
Pressure Switch
10.2.9 Limit
Control
10.2.10 Flame Rollout
Switch—Sizes 30–125
only
2) With the manual valve turned o to prevent ow to the gas valve, connect a
manometer to the 1/8ʺ outlet pressure tap in the valve. NOTE: A manometer (uidlled gauge) is recommended.
3) Turn the manual valve to the ON position and the heater OFF. Use your nger to
fully block the main burner orice for several seconds. Observe the manometer
with the orice blocked, and if any pressure is indicated, the gas valve is leak-
ing. A leaking gas valve must be replaced before the heater is put back in
operation.
See FIGURE 18, page 30, for location. (NOTE: Depending on date of manufacture and
size, pressure switch may not be in the location indicated. Check the control bracket
on the bottom of the compartment or further down on the compartment wall.) If it is
determined that the pressure switch needs replacing, use only the factory-authorized
replacement part that is designed for the model and size of heater being serviced.
NOTE: A unit operating above 6000 ft (1830M) elevation requires a high altitude pressure switch (see Paragraph 3.2).
If it is determined that the limit control needs replacing, use only a factory-authorized
replacement part that is designed for the size of heater.
For approximate limit location, see FIGURE 18, page 30.
The cause of a ame rollout switch activating must be determined. Activation of the
manually reset ame rollout switch could be caused by one or more of the following:
• Restricted or plugged heat
exchanger
• Too much building exhaust
• Manifold gas pressure too
high
• Restricted combustion air inlet or exhaust outlet
in combination with a defective pressure switch
• Electrical power interruption during operation
• Unit being operated with a line voltage
disconnect (a 24-volt thermostat is required)
If a ame rollout switch trips, inspect the burner/control compartment for signs of
excessive heat and burned wiring.
For location, see
FIGURE 18, page 30.
If the compartment appears normal, reset by depressing the red button on the
switch. 15 to 20 minutes are required for the switch to cool suciently for resetting. A distinct click will be felt when the switch resets. Operate the furnace. If the
ame rollout switch trips again, determine and correct the cause before resetting
the switch.
If there is damage to the control compartment, repairs must be made before
resetting the switch.
If it is determined that the ame 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 com-
partment with the toggle on the rear of the heater.
10.2.11 Door
Switch—Separated
Combustion Model
only
Page 34, D300519A (04-18) I-UDA&APD Series
If it is determined that the door switch needs replacing, use only a factory-
authorized replacement part that is designed for the heater.
For approximate switch location, see FIGURE 18, page 30.
10.2.12 Transformer
Trial for Ignition
Call for Heat
Is there a
spark across gap at
ignitor?
Does gas
ignite?
Is there minimum
flame current at the
flame sensor?
Is there
minimum flame current
at the control
module?
Replace control
module.
Check connections to flame
sensor and/or moisture in the
burner assembly.
Is the flame
sensor corroded?
Clean flame
sensor.
Is the sensor
located in flame
correctly?
Replace flame
sesnsor.
Reposition
flame sensor.
Is gas
flowing?
Is the ignitor
position correct in the
gas flow?
Check gas pressure
and supply voltage.
If either are low,
correct and repeat
startup.
Reposition
spark ignitor.
Is there
24VAC at the gas
valve?
Is there 24VAC
from gas valve output on
control module to
chassis?
Check wiring and
connections to
gas valve.
Replace
ignition
control
module.
Replace gas
valve.
Is there
spark voltage at
control?
Check high
voltage wire
continuity.
Is there 24V P1-2
to power control?
Replace
control
module.
Check wiring
and/or 24VAC
transformer output.
YES NO
YES NO
YES NO
YES
NO
YES
NO
YES
NO
YES NO
YES
NO
NO
YES
YES NO
YES
NO
YES
NO
10.2.13 Disconnect
Switch—Separated
Combustion model
only
10.2.14 Vent or Vent/
Combustion Air
System
10.3 Troubleshooting
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.
See FIGURE 18, page 30, for location. Use a voltmeter to verify that
there are 24 volts output from the transformer. If the transformer is not
functioning, it must be replaced. Use a replacement transformer identi-
cal to the factory-installed model.
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 electrical box cover.
Check the complete system at least once a year. Inspection should include all joints,
seams, concentric adapter box (Separated Combustion), inlet air guard or inlet air cap
(Separated Combustion), and the vent terminal cap. Clean openings. Replace any
defective parts.
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 viewport on Separated Combustion models. Remove access panel on Standard Power Vent models. See operating
sequence in Paragraph 9.
Do not attempt to repair the DSI integrated control module (circuit board); the only eld
replaceable component is the fuse.
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 ame
2 Flashes .. Pressure Switch Did Not Close within 30 Seconds of Venter Motor
3 Flashes .. High Limit or Flame Rollout Switch 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 ame (current below 1.0 microamps ± 50%)
Fast Flash ...Undesired Flame (valve open and no call for heat)
DSI Integrated Control Module (Circuit
Board) Trial Troubleshooting Flowchart
D300519A (04-18) I-UDA&APD Series, Page 35
10.3 Troubleshooting (cont’d)
General Troubleshooting
PROBLEM PROBABLE CAUSE REMEDY
Venter motor will not
start
Burner will not light 1. Manual valve not open. 1. Open manual valve.
Burner cycle on and o1. Gas pressure too high or too low. 1. Supply pressure should be 5–14" w.c. for natural gas or 11–14" w.c. for pro
1. No power to unit. 1. Turn on power, check supply fuses or circuit breaker.
2. No 24 volt power to integrated circuit board. 2. Turn up thermostat; check control transformer output.
3. Integrated circuit board fuse blown. 3. Correct cause. Replace fuse (type ATC or ATO, 32VDC, 3A).
4. No power to venter motor. 4. Tighten connections at circuit board and/or motor terminals.
5. Integrated circuit board defective. 5. Replace integrated circuit board.
6. Defective venter motor. 6. Replace venter motor (see Paragraph 29).
2. Air in the gas line. 2. Bleed gas line (initial startup only).
3. Gas pressure too high or too low. 3. Supply pressure should be 5–14" w.c. for natural gas or 11–14" w.c. for
4. No Spark:
a) Loose wire connections a) Be certain all wire connections are solid.
b) Transformer failure.
c) Incorrect spark gap. c) Maintain spark gap at 1/8".
d) Spark cable shorted to ground. d) Replace worn or grounded spark cable.
e) Spark electrode shorted to ground. e) Replace if ceramic spark electrode is cracked or grounded.
f) Burner not grounded. f) Make certain integrated circuit board is grounded (Terminal P1-9).
g) Circuit board not grounded. g) Make certain integrated circuit board is grounded to furnace chassis.
h) Unit not properly grounded. h) Make certain unit is properly eld grounded to earth ground and properly
i) Integrated circuit board fuse blown. i) Correct cause. Replace fuse (type ATC or ATO, 32VDC, 3A).
j) Faulty integrated circuit board. j) If 24 volt is available to the integrated circuit board and all other causes have
5. Lockout device interrupting control circuit by
above causes.
6. Combustion air proving switch not closing. 6.
7. Faulty combustion air proving switch. 7. Replace combustion air proving switch.
8. Main valve not operating. 8.
a) Defective valve. a) If 24 volt is measured at the valve connections and valve remains closed,
b) Loose wire connections b) Check and tighten all wiring connections.
9. Integrated circuit board does not power main
valve.
a) Loose wire connections. a) Check and tighten all wiring connections.
b) Flame sensor grounded. b) Be certain ame sensor lead is not grounded or insulation or ceramic is not
c) Incorrect gas pressure. c) Supply pressure should be 5–14" w.c. for natural gas or 11–14" w.c. for pro
d) Cracked ceramic at sensor. d) Replace sensor.
2. Burner not grounded 2. Make certain integrated circuit board is grounded (Terminal P1-9).
3. Circuit board not grounded. 3. Make certain integrated circuit board is grounded to furnace chassis.
4. Faulty integrated circuit board 4. If 24 volt is available to the integrated circuit board and all other causes have
5. Combustion air proving switch not closing. 5.
6. Faulty combustion air proving switch. 6. Replace combustion air proving switch.
7. Flame sensor grounded. 7. Be certain ame sensor lead is not grounded or insulation or ceramic is not
8. Cracked ceramic at sensor. 8. Replace sensor.
9. Incorrect polarity. 9. Reverse line volt leads to integrated circuit board.
10. Pin terminal loose on 9 pin plug. 10. Replace wire harness.
:
propane.
4.
b) Be sure 24 volts is available.
phased (L1 to hot lead L2 to neutral).
been eliminated, replace board.
5. Reset lockout by interrupting control at the thermostat or main power.
a) Make sure unit is properly vented.
b) Remove obstructions from vent.
c) Replace faulty tubing to pressure switch.
replace valve.
9.
cracked. Replace as required.
pane.
pane.
been eliminated, replace board.
a) Make sure unit is properly vented.
b) Remove obstructions from vent.
c) Replace faulty tubing to pressure switch.
cracked. Replace as required.
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Page 36, D300519A (04-18) I-UDA&APD Series
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