1. No problem, normal operation
2. Blown fuse.
3. Faulty blower
4. Blocked venting
5. Blocked air inlet
6. Disconnected, damaged or blocked tubing
7. Incorrect air switch setting.
8. Faulty air proving switch
9. Tripped High Vent Pressure Switch
10. Tripped Thermal Fuse
11. Tripped Door Reset Safety Switch
12. Incorrect air switch wiring
1. Hold 65 will normally be displayed momentarily during the drive to light-off.
2. Check Fuse "A", blown fuse prevents blower from operating.
3. If Fuse “A” is good and blower remains off, check 120VAC supply to blower, if present replace blower. If blower is on proceed to next step.
4. Check for blockage of the exhaust vent.
5. Check for blockage of the air inlet.
6. Inspect the clear vinyl tubing connecting the air switch + and – ports to the air metering elbow. Condensation or other foreign matter may be obstructing the tubing, preventing the switch from sensing differential pressure caused by air flow through the metering elbow.
7. Contact NTI technical support.
8. If venting and air inlet are clear, temporarily jumper the air switch. If the unit lights and operates smoothly – replace air switch. If the unit fails to light or lights but runs rough or abruptly shuts down – check boiler internals for blockage. WARNING Only jumper the air switch for diagnosing purposes.
9. The high vent pressure switch will trip when the combustion chamber is blocked. Clean combustion chamber and reset switch.
10. Check Thermal Fuse on the back of the heat exchanger (accessed from the rear of the cabinet). If tripped contact NTI.
11. The Door Reset Safety Switch will trip with the combustion chamber gets dirty or the door insulation fails. Clean the combustion chamber, inspect the door insulation and reset the switch.
12. Check that the red and orange wires are connected to quick connect tabs 3 and 1 respectively.
