The manufacturer of boilers, NTI is an industry leader. This family-run business exists for more than 40 years. The company strives constantly to improve its products. And this is evident throughout everything. Just see its efforts to help ordinary users in case of equipment failure. Below you will find the table with NTI boiler error codes.
| Symptom | Detected Problem | Solution |
|---|---|---|
| ER1 | “Water Temperature Excessive” Sentry has sensed a water temperature in excess of 250°F at the Water Sensor. | 1. If the boiler is extremely hot check for adequate water pressure and circulation, contact NTI for assistance. |
| 2. If not hot, check for sources of grounding or shorting at the Water Sensor electrical connections, check wiring from Sensor to Boiler (Red) Control. | ||
| 3. Replace Water Sensor if the resistance is not in the correct range. | ||
| ER2 | “Water Sensor Short Circuit” Control has sensed a short circuit in the Water Sensor circuit. | See ER1 |
| ER3 | “Water Sensor Open Circuit” Control has sensed an open circuit in the Water Sensor circuit. | 1. Check wiring to Water Sensor for open circuits or shorting to ground. (Note: ER3 will be displayed if temperature sensed is less then 0°F.) |
| 2. Replace Water Sensor if the resistance is not in the correct range. | ||
| ER4 | “24V Limit Error” Control has sensed a lack of 24V on the outlet of the burner relay (B1). Lockout lasts for one hour before automatically resetting. | 1. Reset power, if error goes away the problem is intermittent and was likely caused by a tripped limit that has automatically reset, check for adequate water pressure and flow rate. Allow the boiler to cycle and verify proper operation including outlet water temperature and flue temperature. If operation is unsuccessful and the error reoccurs: |
| 2. Matrix boilers are equipped with a low water pressure switch on the boiler return that requires a minimum of 10PSI to complete the 24VAC ignition circuit. Ensure the field-installed pressure gauge is reading a minimum of 12PSI. Replace water pressure switch if plumbing and pressure is correct and if it measures an open circuit. | ||
| 3. Check for continuity through the 24VAC limit wiring and manifold and stack limits, replace limits or wiring that are not a closed circuit. | ||
| ER6 | “Flame Lock Out” Control has sensed a lack of 24V to the gas valve during operation or a Fenwal ignition lockout. | There is a problem in the ignition sequence; it could be caused by a faulty igniter, flame sensor, gas valve or improper line pressure or combustion. Check ignition sequence to determine which component is not functioning. (Control will retry ignition sequence 1 hour after ER6 code originally occurs or if control is reset) |
| ER9 | Internal Controller Fault | Indicates that the Controller has lost communication with an internal processor, contact NTI. |
| ASO Air Switch Open | This is displayed when the boiler is expecting the air switch to be closed by a differential pressure generated when the combustion blower turns on. It can occur momentarily during normal operation. A problem is indicated when ASO is displayed continuously. | 1. Ensure the vinyl tubes, connected between the air switch and the ports on the inlet pipe, are in the proper locations. Negative side of switch connects to the port on the 1-1/2” PVC elbow. |
| 2. Check for blockage on the intake and exhaust vents. | ||
| 3. If fan is running the air switch may be faulty, ensure it is set at 0.2”wc. | ||
| 4. If fan is not running, check 120V wiring to blower, if ok remove low voltage harness from blower, if blower fails to start, replace blower, if blower does start the problem may be with blower or Controller. | ||
| ASC Air Switch Closed | This is displayed when the boiler has turned the blower off and is expecting the air switch to be open. It can occur momentarily during normal operation. A problem is indicated when ASC is displayed continuously. | 1. Does the combustion fan run continuously at full speed while the error is displayed? If so check for 24V from transformer, also check transformer fuse. If 24V is present check the low voltage wiring from Controller to combustion blower, replace Controller or Blower. |
| 2. Is the combustion fan off? If so check for water in the air switch and air switch tubes, replace switch if necessary. | ||
| 3. Check venting termination with required venting described in manual. | ||
| Controller Locks-up | Excessive noise, current, or voltage spikes in the 120V power supply. | Contact NTI. |
| Display Goes Blank | No power to control or control failure | 1. Check for 120V between terminals L1 and L2. |
| 2. If 120V exists turn power off and remove line voltage harness from Control. Then check for resistance between L1 and L2 of control, if the circuit is open (O.L) the internal fuse has blown. Check for shorts in wires leading to circulator prior to replacing controller. (Note: If fuse is good the circuit will read between 300 and 400 Ohms.) | ||
| 3. If 120V not present, check wiring and for 120V at source. | ||
| AL1 | Communication Error with HRV | 1. Check wiring connections between HRV and Fan Controller. |
| 2. Check door switch on HRV. | ||
| 3. Cycle power to appliance; contact NTI. | ||
| AL2 | Plenum Temperature Limit of 160°F Exceeded | 1. If plenum is hot, check operation of blower fan; contact NTI. |
| 2. If plenum is not hot, check plenum sensor and wiring for shorts or damage. | ||
| 3. Remove plenum sensor, PSO should be displayed, if so replace plenum sensor, if not inspect wiring from Terminal Strip to Fan Control. Replace Fan Control if necessary. | ||
| AL5 | “DHW Time-Out” The Control has locked out DHW due to the demand lasting longer than 2.5 hours. | 1. Reset the AL5 error by resetting the power or cycling the DHW call. Check for proper operation of the DHW call. |
| 2. Matrix units are provided with an integrated DHW flow meter, if the control is registering a flow rate when the water is turned off; disconnect the electrical lead to the flow meter. If the indicated flow rate drops to 0, replace flow meter, if not, replace fan controller. | ||
| 3. Ensure nothing is connected to the FS terminal of the terminal strip (unless using a DHW tank aquastat to trigger a demand – check operation of aquastat). | ||
| AL7 | ‘Boiler Control Error’ Fan controller has failed to receive run status from Boiler Control. | 1. Check for error code on Boiler Control. |
| 2. Check control wiring from Boiler Control to Fan Control. | ||
| AL8 (& Blower Off) | ‘Furnace Blower Error’ Blower has failed to meet a minimum speed. | 1. Check for 120V to blower; ensure door switches are making the circuit. |
| 2. Check wiring from Pin 6 at Fan Control (white wire) to Pin 15 at blower motor. | ||
| 3. Check for 24VDC at blower Pin 15, if present replace blower, if not replace Fan Control. | ||
| AL8 (& Blower On) | ‘Furnace Blower Error’ Control has failed to sense that the blower has reached a minimum speed. | 1. Check wiring from Pin 5 at Fan Control (black wire), to Pin 16 at blower motor. |
| 2. Check for 3-5VDC at blower Pin 16, if present replace blower, if not replace Fan Control. | ||
| F3.5 Flashing | Lack of 24 V at fan controller | 1. Check/Replace 2A fuse – blown fuse indicates 24V supply shorted to ground, or excessive load. |
| Two Flashes on Fenwal | The Fenwal controller thinks that there is a flame prior to ignition. Indicates Ignition Lockout. | If the combustion sequence is normal, and there is no flame prior to ignition, the Fenwal control is defective, and must be replaced. |
| Code | Description |
|---|---|
| Loc 1 | Ignition Error – three unsuccessful ignition attempts in a row, perform the following checks: 1. Check venting for blockages. 2. Check condensate trap from proper draining. 3. Static gas pressure – if insufficient check gas supply-lines and regulator. 4. Gas pressure during ignition – if the static gas pressure is sufficient, check pressure during ignition sequence, i.e. when gas valve opens. a. If pressure drops below minimum (4” for NG / 8” for LP), check gas supply-line and regulator. b. If pressure does not move, verify 120V AC at valve during ignition; if no power, check wiring – replace control; if power is present – replace gas valve. c. If pressure drops slightly – proceed to next step 5. Unit ignites but immediately goes out – check flame sensor (clean or replace) and flame sensor cable, clean combustion chamber, replace control. If a combustion analyzer is available, adjust throttle screw out 1 turn – check/adjust combustion once unit is operational. 6. Unit fails to ignite – check spark electrode and cable (replace). Verify the spark electrode is arcina. WARNING!! – maintain clearance from isnition components while the Dower is on to avoid risk of severe electrical shock. 7. Unit ignites and runs – check combustion at maximum and minimum modulation rates. |
| Loc 2 | Gas Valve Circuit Fault (Safety) – control has sensed a fault in the gas valve electrical circuit, check for a loose connection in the gas valve wiring harness. Also see “Loc 5”. |
| Loc 3-4 | Controller Malfunction – contact NTI, replace controller. |
| Loc 5 | Limit Circuit Open (Safety ) – control has sensed a fault in the safety limit circuit; check the following: 1. External Limit (Purple wire) – if an external limit device (i.e. LWCO) is connected to the purple wire at the field wiring terminal, check to ensure it has not tripped, and that it is wired correctly. 2. Internal Limit (Heat Exchanger Thermal Fuse) – the heat exchanger is equipped with a normally closed thermal fuse; the fuse opens when the heat exchanger gets too hot. If the fuse is open, contact NTI. |
| Loc 6-9 | Controller Malfunction – contact NTI, replace controller. |
| Loc 10 | Supply Sensor Fault – controller has sensed an invalid reading at the Supply/Outlet sensor; check cable, then replace sensor. |
| Loc 11 | Uncorrected Blocking Error – a blocking error (Err) has lasted for 20 consecutive hours. |
| Loc 12 | Incorrect Fan Speed – measured fan speed is not reaching target fan speed within 60 seconds. Check wiring to fan, replace fan. |
| Loc 13-26 | Controller Malfunction – contact NTI, replace controller. |
| Loc 27 | Flame present 10 seconds after closing gas valve – verify flame is going out immediately following the end of a burner demand; check flame sensor (replace); check condensate drain for blockages; increase post purge setting. |
| Loc 28 | Flame present before ignition – check flame sensor (replace); check condensate drain for blockages; increase post purge setting. |
| Loc 29 & up | Controller Malfunction – contact NTI, replace controller. |
| Err 45-51 | |
| Err 52 | Incorrect Field Wiring – check electrical connections to field terminal strip; ensure the Thermostat is connected to terminals 7 and 8. |
| Err 53 | Controller Malfunction – contact NTI, replace controller. |
| Err 54 | Flame detected out of sequence – check/replace flame sensor; check flame sensor wiring; check condensate drain for blockages; replace controller. |
| Err 55-60 | Controller Malfunction – contact NTI, replace controller. |
| Err 61 | Return Sensor Error – check wiring to return sensor; replace sensor. |
| Err 62-64 | Controller Malfunction – contact NTI, replace controller. |
| Err 65 | Incorrect Polarity – controller has sensed reversed polarity of the 120VAC power supply; check field wiring to L2 NEUTRAL (terminals 12&13) and Ll 120VAC (terminal 14). There should be I20VAC potential between LI 120VAC and ground, and 0VAC potential between L2 NEUTRAL and ground. |
| Err 66 | Incorrect Frequency – the controller accepts a line voltage frequency of 601 Iz ± 2%; if outside this range the controller may be damaged or function incorrectly. If using a generator as a power source, install a UPS (uninterruptible power supply) between the generator and boiler. |
| Err 67 | Faulty Earth Ground – check grounding of boiler and power supply; replace controller. |
| Err 68-71 | Controller Malfunction – contact NTI, replace controller. |
| Err 72 | Supply Sensor Open – check wiring to supply sensor; replace sensor. |
| Err 73 | Return Sensor Open – check wiring to return sensor; replace sensor. |
| Err 74-77 | Controller Malfunction – contact NTI, replace controller. |
| Err 78 | Flue Sensor Open – check wiring to flue sensor; replace sensor. |
| Err 79 | Controller Malfunction – contact NTI, replace controller. |
| Err 80 | Supply Sensor Shorted – check wiring to supply sensor; replace sensor. |
| Err 81 | Return Sensor Shorted – check wiring to return sensor; replace sensor. |
| Err 82-85 | Controller Malfunction – contact NTI, replace controller. |
| Err 86 | Flue Sensor Shorted – check wiring to flue sensor; replace sensor. |
| Err 87 & up | Controller Malfunction – contact NTI, replace controller. |