Brivis Heater Not Igniting? Common Fault Parts and Fixes
Written by Rica Francia Macaspac, HVAC Shop content writer, in consultation with Aussie HVAC tradies and industry experts. Published: June 2026 · Last reviewed: June 2026.
A Brivis heater that refuses to ignite is one of the most common call-outs for HVAC technicians across Australia. The problem peaks at the start of winter when heaters fire up for the first time in months and components that have been sitting idle through a Sydney summer or a Perth dry season decide to fail. The good news is that no-ignition faults on Brivis ducted gas heaters follow a predictable pattern. Five main component categories cause the vast majority of ignition failures, and working through them in the right order gets you to the correct diagnosis and the correct replacement part without guesswork. This guide covers each one: what to check and what to order once you have found the fault.
Why Brivis Heaters Fail to Ignite: Understanding the Ignition Sequence
Before diving into individual fault components, it helps to understand the ignition sequence Brivis heaters follow. The sequence is tightly controlled by the PCB (control board), and a failure at any point in the chain will prevent the heater from firing. Understanding the sequence helps you diagnose in order rather than jumping straight to the most expensive component.
When a call for heat arrives from the wall controller, the control board runs through a safety check sequence. First, it verifies that the pressure switch is in the open (no-pressure) position, confirming the combustion fan has not pre-tripped. The combustion fan then starts and runs up to speed, creating airflow through the heat exchanger. Once the fan is running, the pressure switch should close as it detects the pressure differential, confirming adequate airflow is established. With airflow confirmed, the board activates the igniter and opens the pilot gas supply. The pilot burner lights, and the flame sensor (typically a thermocouple) detects the pilot flame and generates a voltage signal. With a valid flame signal confirmed, the main gas valve opens and the main burner lights. The thermistor monitors heat exchanger temperature throughout the entire operation.
A fault at any step causes the control board to lock out and halt the sequence. Common symptoms that point to a no-ignition fault include the heater clicking repeatedly but not lighting, a brief flame that extinguishes immediately after the igniter stops, a fault code on the wall controller (E1, E3, or similar depending on model), or the system appearing to start with the fan running and clicking audible but producing no heat at all. Work through the fault categories below in order, as each one is more likely than the next.
1. Pilot Burner and Ignition Assembly Faults
The pilot burner and ignition assembly are the first place to look on a no-ignition fault. These components sit at the heart of the ignition sequence and are among the most common failure points on heaters that have been in service for five or more years, especially in environments where dust accumulation is a factor. Think older homes in regional New South Wales, poorly sealed roof spaces in Queensland, or units that have not been serviced in several years.
The pilot burner is a small gas orifice with an igniter electrode positioned to create a spark and light the pilot flame. Failure modes include a blocked pilot orifice that prevents gas flow, a cracked or fouled igniter electrode that prevents spark, or a broken ignition lead with no electrical path to the electrode. The symptom of a faulty pilot burner is typically continuous clicking with no visible flame at all. The board is activating the igniter correctly; the problem is at the pilot orifice or electrode itself.
Rather than sourcing individual sub-components, the cleanest resolution for most pilot and ignition faults on Brivis heaters is to replace the entire assembly as a unit. The Brivis HCCA621 pilot lead assembly (BS80021192) includes the pilot burner, ignition lead, and associated components as a complete kit. Replacing the whole assembly rather than individual parts reduces diagnostic time on site and avoids the scenario of replacing one sub-component only to find another has failed shortly after.
Installation of the pilot assembly involves gas connections and must be carried out by a licensed gas fitter in accordance with AS/NZS 5601. A homeowner can identify the fault and source the part, but the installation step requires a licence.
Tradie Pro Tip: Before condemning the pilot assembly on a clicking-but-no-light fault, check the gas supply first. A closed isolation valve or a depleted LPG cylinder is an embarrassingly common cause of no-ignition calls, particularly on systems that have been idle over summer. Takes thirty seconds to verify and saves you pulling the unit apart unnecessarily.
2. Flame Sensor and Thermocouple Failures
If the pilot lights but the heater shuts down within five to thirty seconds of the igniter stopping, the thermocouple is almost always the culprit. This is one of the most textbook fault presentations in gas heating, and once you have seen it a few times it becomes immediately recognisable.
The thermocouple is a flame-sensing device positioned in the pilot flame. When heated by the pilot, it generates a small millivolt DC signal, typically in the 15 to 30mV range on a healthy unit. The control system uses this signal to confirm that a valid flame is present, and the signal holds the gas valve open. As a thermocouple ages, the junction between the dissimilar metals degrades and the output voltage drops. When the output falls below the threshold required to hold the gas valve open, the valve closes and the flame goes out, even though the pilot itself was working correctly. The result is a pilot that lights cleanly every time but goes out as soon as the igniter cycle finishes.
Thermocouple output can be measured with a multimeter set to the millivolt DC range. Clip the probes across the thermocouple output terminals with the pilot flame lit and allow at least sixty seconds for the reading to stabilise. A reading below around 12 to 15mV indicates a thermocouple that is marginal or failing; a reading of 0 to 5mV confirms failure. A healthy thermocouple should read 15 to 30mV. Confirm the acceptable range against the manufacturer's documentation for your specific model, as thresholds vary between units.
Thermocouple replacement requires matching the correct length and termination type to the original. The 24 inch clip and nut variant suits more recent Brivis models and is one of the most commonly replaced thermocouple types across the range. Order the Brivis thermocouple replacement after confirming the length and termination type on the original component. Thermocouple replacement requires disconnection from the gas valve and must be performed by a licensed gas fitter.
3. Thermistor Faults and Temperature Sensing Errors
The thermistor is a temperature-sensing resistor positioned in or near the heat exchanger. Where the thermocouple confirms flame presence, the thermistor monitors heat exchanger temperature during operation and feeds this data to the control board. The board uses this reading to confirm the heat exchanger is reaching operating temperature, to detect overheating, and to trigger a safety lockout if the temperature rises beyond safe limits.
A faulty thermistor can cause a range of no-ignition or lockout symptoms that are harder to diagnose than a straightforward pilot or thermocouple fault. If the thermistor reads an erroneously high temperature at startup due to a failed component, corroded wiring, or a damaged loom, the control board may interpret this as an overheat condition and refuse to initiate the ignition sequence at all. A thermistor reading abnormally low can cause the board to run extended heating cycles, triggering a different class of fault or lockout.
Thermistor resistance can be checked with a multimeter set to resistance (ohms). With the heater cold and at ambient temperature, the thermistor should read within the expected resistance range for its rated temperature. Consult the service documentation for your specific model for the correct cold-resistance value. A reading of zero ohms (short circuit) or infinite ohms (open circuit) confirms a failed thermistor. Check the wiring loom for corrosion or damage at the same time, as loom faults can produce the same symptoms as a failed thermistor sensor.
The Brivis thermistor lead (BS80019789) is supplied with the wiring loom and mounting bracket as a complete assembly, which simplifies replacement and addresses both the sensor and loom in a single part. Replacing the sensor alone without addressing a damaged loom leaves the problem partially resolved, so the complete assembly is the right approach for thermistor faults.
4. Pressure Switch Lockout
The pressure switch is a safety component that sits between the combustion fan and the gas valve in the control circuit. Its job is to confirm that the combustion fan is drawing air through the heat exchanger at the correct rate before the gas valve is permitted to open. If the pressure switch does not detect the correct pressure differential because the fan is not running, the fan is underperforming, the pressure tubing is blocked, or the switch itself has failed, the control board will lock out the ignition sequence and no gas will flow to the burner.
Pressure switch faults fall into two categories. The first is a genuine airflow problem where the switch is working correctly but the fan or ducting is not performing. The second is a switch failure where the fan is running correctly but the switch is not detecting or reporting the pressure correctly. Diagnose these separately. Start by confirming that the combustion fan is running and that the pressure tubing between the fan housing and the switch is clear and undamaged. Then test the switch electrically. With the fan running, the switch should close its contacts and pass continuity. If continuity is absent with the fan running at speed, the switch has failed.
Pressure switch replacement requires matching the Pa rating of the original switch exactly. This is the most common ordering error in the entire Brivis parts range. A switch that is physically identical to the original but carries a different Pa rating will produce either a permanent lockout or an unsafe operating condition. Read the Pa rating from the label on the original switch before ordering. For units fitted with the 165Pa switch, order the Brivis 165Pa pressure switch (BS80021376). Do not substitute with a different Pa-rated switch even if another rating is in stock or more readily available.
| Fault Symptom | Most Likely Cause | Diagnostic Check | Replacement Part |
|---|---|---|---|
| Clicking with no flame at all | Pilot burner or ignition assembly fault | Check gas supply first, then inspect pilot orifice and electrode | HCCA621 pilot lead assembly |
| Pilot lights then goes out after 5 to 30 seconds | Thermocouple failure (low millivolt output) | Measure thermocouple mV output with pilot lit. Below 12 to 15mV indicates failure | Thermocouple (match length and termination) |
| Fan runs but ignition sequence never starts | Pressure switch not closing or combustion airflow fault | Test switch continuity with fan running. Check pressure tubing for blockage | Pressure switch (must match Pa rating exactly) |
| Lockout at startup with no obvious cause | Thermistor fault (erroneous temperature reading at startup) | Check thermistor resistance at ambient temperature. Inspect loom for damage | Thermistor lead with loom and bracket |
| All components check out but no ignition | Control board (PCB) fault | Last resort after all other faults ruled out. Check board for visible damage | N-E6 control board (confirm with or without switch variant) |
5. Control Board Lockout
The control board (PCB) is the component of last resort in a no-ignition diagnosis. It manages the entire ignition sequence and can cause any of the symptoms described above if it fails, which is exactly why it can be tempting to jump straight to replacing it when a fault proves difficult to diagnose. Resist that temptation. Control boards are among the higher-cost items in the Brivis spare parts range, and board failure is genuinely less common than ignition assembly, thermocouple, thermistor, or pressure switch failure. Replacing a board when the actual fault is a twenty-dollar thermocouple is an expensive and unnecessary outcome.
The correct approach is to work through all other fault categories first. Test the thermocouple output. Confirm the pressure switch is operating correctly. Check the thermistor resistance. Inspect the pilot assembly and ignition electrode. Only after all other fault categories have been checked and cleared should the control board be considered as the likely cause.
Signs that point more directly to a board fault include visible burn marks, scorch damage, or bulging capacitors on the PCB face; faults that appear completely random with no relationship to any specific point in the ignition sequence; or a unit where all external components test correctly but the board fails to advance through the ignition sequence despite receiving valid inputs. In these cases, the N-E6 board replacement is the appropriate next step.
As covered in the part identification guide, the N-E6 exists in two variants. Confirm which variant is fitted before ordering: the board with integrated switch (BS81008783) or the board without switch (BS81065300). The Brivis N-E6 control board with integrated switch is one of the most commonly replaced boards across the Brivis, Braemar, and Bonaire platform. Control board replacement should be performed by a qualified HVAC technician. Commissioning following PCB replacement, including gas ignition testing, requires a licensed gas fitter.
Did You Know? Intermittent no-ignition faults that clear themselves overnight are often thermistor-related rather than board faults. A thermistor reading high due to residual heat from a previous cycle can cause a startup lockout that clears once the heat exchanger returns to ambient temperature. If the fault disappears when the unit is cold but returns after the heater has run for a while, test the thermistor before touching the board.
6. When to Call a Licensed Gas Fitter
Understanding the legal framework around Brivis heater repairs matters for both homeowners and HVAC technicians. In Australia, the rules are clear and consistent across all states. The diagnostic work, which includes identifying a fault, testing components, and determining which part has failed, is legal for anyone to perform. Sourcing and purchasing the replacement part is also fully legal for a homeowner or unlicensed technician. What requires a licence is the installation step, specifically the physical connection of gas components.
Under AS/NZS 5601.1 (Gas Installations), any work that involves connecting, disconnecting, or modifying a gas appliance or gas fitting must be carried out by a licensed gas fitter. This covers the installation of pilot assemblies, gas valves, burners, thermocouples (which connect to the gas valve), and any other component that is part of the gas circuit. It also covers the commissioning and testing of the gas system following a repair. The licence requirement is enforced by state regulators across all Australian jurisdictions. For current licencing requirements in your state, refer to Safe Work Australia.
For homeowners, the practical upshot is that diagnosing the fault and having the correct replacement part ready before the gas fitter arrives is a perfectly sensible approach. It reduces call-out time, reduces the risk of a return visit for parts, and puts you in control of the parts sourcing process. A homeowner who has correctly identified a thermocouple fault and has the right replacement part on hand makes for a much more efficient service call than one who waits for the gas fitter to diagnose and source everything on the day.
There are situations where you should stop diagnosing and call for professional help immediately, regardless of what the fault appears to be. If you smell gas at any point during the diagnostic process, stop, ventilate the area, and call the gas emergency line (1800 427 532) before doing anything else. If you or anyone in the home is experiencing symptoms consistent with carbon monoxide exposure, including headache, dizziness, nausea, or confusion, evacuate immediately and call emergency services. These are gas safety emergencies that require an immediate professional response, not continued diagnosis.
For all other no-ignition faults, source your replacement part from our range of genuine Brivis replacement parts and have it ready for your licensed gas fitter to install. All parts are stocked in Australia and dispatched Australia-wide, so you are not waiting on international freight when your heating is down in the middle of a Canberra or Ballarat winter.
Tech Specs: Gas Emergency Contacts If you smell gas or suspect a gas leak, do not attempt any further diagnosis. Leave the area, avoid operating any electrical switches, and call the gas emergency number: 1800 427 532 (available 24/7 in most states). For carbon monoxide concerns, call 000 immediately.
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