Thomas & Betts UDAS Flame Rollout Switch - Sizes 30-125 only, Disconnect, Vent or Vent, Flowchart

• Restricted combustion air inlet or exhaust outlet in combination with a defective pressure switch

• Building exhaust

• Electrical power interruption during operation

37.Flame Rollout Switch - Sizes 30-125 only

For location, see FIGURE 18, page 31.

The cause of a flame rollout switch activating must be determined. Activation of the manually reset flame rollout switch could be caused by one or more of the following:

• Restricted or plugged heat exchanger

• Pressurization of the heat exchanger

If a flame rollout switch trips, inspect the burner/control compartment for signs of excessive heat and burned wiring.

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 sufficiently for reset- ting. 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 reset- ting the switch.

If there is damage to the control compartment, repairs must be made before

resetting the switch.

If it is determined that the flame rollout switch needs replacing, use only the fac- tory-authorized replacement part that is designed for that size of heater.

38. Disconnect	The disconnect switch is located in the sealed electrical box inside the con-
	trol compartment with the toggle on the rear of the heater.
Switch -
	If it is determined that the disconnect switch needs replacing, use only the
UDAS only	factory-authorized replacement part that is designed for the heater. Always
	replace electrical box cover.
39. Vent or Vent/	Check the complete system at least once a year. Inspection should include all joints,
Combustion	seams, concentric adapter box (UDAS), inlet air guard or inlet air cap (UDAS), and
	the vent terminal cap. Clean openings. Replace any defective parts.
Air System

40. Troubleshooting

DSI Integrated Control Module	Trial for Ignition
	Call for Heat
(Circuit Board) Trial
	Is there a	NO
YES	spark across gap at
Troubleshooting
	ignitor?
Flowchart		Is there	YES
YES Does gas NO		spark voltage at
ignite?
		control?
		NO

Check high voltage wire continuity.

YES	Is there minimum	NO	Is the flame	YES	Clean flame
	flame current at the		sensor corroded?
					sensor.
	flame sensor?

NO

Is there 24V P1-2	YES
to power control?
NO

Replace control module.

Is there

minimum flame current YES at the control

module?

NO

Replace control

module.

Is the sensor	YES	Replace flame
located in flame
		sesnsor.
correctly?

NO

Check wiring

and/or 24VAC

transformer output.

Check connections to flame sensor and/or moisture in the burner assembly.

Reposition

flame sensor.

Check gas pressure and supply voltage.

YES

YES

Is the ignitor

Is gas	NO
flowing?
Replace gas	YES	Is there

If either are low, correct and repeat startup.

position correct in the

gas flow?

NO

Reposition

spark ignitor.

	valve.		24VAC at the gas
			valve?
			NO
			Is there 24VAC
Check wiring and		YES		NO
			from gas valve output on
	connections to
			control module to
	gas valve.
			chassis?

Replace ignition control module.

Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 34