PROBLEM

PROBABLE CAUSE

REMEDY

High flue gas stack temperature indicator light is off.

1. High flue gas stack switch is tripped.

1. Remove cover from switch and reset switch.

2. Strainer is clogged.

2. Remove and clean strainer.

3. Helical coil in heater is coated with soot.

3. Remove end cover of heater and clean coil per separate Tec-Note on service.

Low media level indicator light is off.

1. Level of media (thermal fluid) in expansion is too low.

1. Add thermal fluid to expansion tank. Also check piping to ensure there are no leaking connections.

Media level sight gage does not accurately indicate fluid level in expansion tank.

1. Two valves on sight gauge not open.

1. Open both valves on sight gauge. Use measuring stick through tank filler pipe to confirm accuracy of gauge.

Burner does not modulate.

1. Low fire hold switch in HOLD position.

1. Set switch to NORMAL position.

2. Dip switches of modulating actuator TZ4-1 not set properly.

2. Re-set dip switches per settings shown on wiring drawing furnished with heater. Use ball point pen to make sure switches are fully depressed!

3. Low fire hold temperature of UDC3300 is set too high.

3. Reset low fire hold temperature of UDC3300 to a lower temperature.

4. Defective power transformer in modulating actuator TZ4-1.

4. Check the transformer in the actuator and replace it if defective per separate Tec-Note on service.

5. Defective resistor board in modulating actuator TZ4-1.

5. Check the resistor board in the actuator and replace if defective per separate Tec-Note on service.

Fuel oil pressure low or erratic.

Damaged fuel pump drive coupling.

Remove blower and coupling, inspect spline for damage and slippage. Replace if damaged.