Last updated: 25 June 2026  ·  Originally published: 22 June 2026

Quick Answer

Most ducted gas heaters in Melbourne stop working due to five common causes: a blocked filter (clean it yourself in 10 minutes), a faulty thermostat setting, a tripped circuit breaker, a pilot light outage, or a fault code on the controller. DIY checks clear about 60–70% of breakdowns. If the unit shows a fault code, smells like gas, or doesn’t respond after basic resets, call a licensed gas technician — do not attempt to disassemble the burner yourself.

It’s 7am on a Melbourne winter morning, the temperature is 6°C, and your ducted heating has stopped working. Before you call a technician (and pay $150–$250 for a callout), work through these checks — most Melbourne homeowners find the fix themselves in under 20 minutes.

This guide covers the most common reasons ducted gas heating fails in Melbourne homes (particularly older brick and weatherboard properties in the south-east corridor — Berwick, Narre Warren, Cranbourne, Frankston, Officer, Pakenham) and what you can actually do yourself versus when to call a licensed gas fitter.

Checking the fault code display on a ducted gas heating unit
Checking the fault code display on a ducted gas heating unit — the controller panel shows error codes that identify most common faults without opening the unit.

Quick Diagnosis: Check These First

Before assuming the worst, run through this rapid checklist. These are the most common causes of a ducted heater failing to start — in rough order of likelihood for Melbourne homes:

Symptom Most Likely Cause DIY Fix? Typical Fix Time
Won’t turn on at all, no display Power — tripped circuit breaker or switched off at isolator Yes 2–5 min
Thermostat shows set temp but no heat Thermostat set too low, or in cooling/fan-only mode Yes 2 min
Fan runs but no warm air Blocked filter starving airflow, pilot light out, or gas off Partly — filter yes, gas/pilot check yes but relight may need a tech 10–30 min
Starts, then shuts off after 2–3 min Overheating protection — almost always a clogged filter Yes — clean the filter 15 min
Fault code on controller display Various — look up the code in the owner’s manual Some codes yes, others need a tech Depends on code
Gas smell near unit Gas leak — potentially dangerous No — leave house, call gas emergency line immediately Emergency
Clicking but won’t ignite Igniter fouled, pilot light problem, or low gas pressure Partly — clean igniter electrode, check gas supply 20–40 min
Only some zones heating Zone damper stuck closed, zone controller fault Partly — check zone settings; stuck dampers need a tech 10–30 min
Pro tip: Write down the exact fault code (usually a letter + number like “F3” or “E1”) before calling a technician. Many Melbourne HVAC companies can diagnose the issue over the phone and give you a more accurate quote if you have the model number and fault code ready.
A zone controller showing the set temperature
A zone controller showing the set temperature — if the room temperature is already above the set point, the heater won’t activate even though it appears on. Try increasing the thermostat set temperature by 3–4°C above the current reading.

DIY Checks: Step by Step

1. Check Power and the Isolator Switch

Every ducted gas heater has a 240V electrical isolator — usually a standard powerpoint or a dedicated switch near the unit (often in the garage, roof space, or a hallway cupboard). Check it’s switched on. Also check your switchboard: the heater breaker is typically labelled “heating” or “HVAC.” Reset it once if it’s tripped.

If the breaker trips again immediately, stop — there’s an electrical fault. Don’t reset it a second time. You’ll need an electrician.

2. Check the Thermostat or Controller

This is the most commonly overlooked fix. Confirm:

  • The controller is set to Heating mode (not Cooling or Fan Only)
  • The set temperature is at least 2–3°C above the current room temperature
  • The timer hasn’t been accidentally set to run only during certain hours
  • Batteries in wireless controllers are fresh (replace if the display is dim)

3. Clean the Return Air Filter

A blocked filter is the single most common cause of ducted heaters running briefly then cutting out. Melbourne’s dust, pollen, and pet dander clog filters fast — particularly in older Berwick, Narre Warren, and Frankston homes with carpeted floors.

  1. Locate the return air grille — usually a large louvred vent in the ceiling, hallway, or laundry, separate from the smaller outlet vents
  2. Open the grille by releasing the two clips on the edge
  3. Slide out the filter — it will be a flat foam or fibreglass pad
  4. Vacuum both sides or wash with warm water (foam filters only) — allow to dry completely before reinstalling
  5. Reinstall and test — the heater should now run a full cycle without shutting off
Pro tip: Melbourne’s pollen season (August–November) and dry summer dust mean filters should be cleaned every 6–8 weeks during heavy use periods, not just “once a year” as many manufacturers suggest. Set a calendar reminder.
Removing a dirty return air filter from the ceiling return grille
Removing a dirty return air filter from the ceiling return grille — a filter this clogged restricts airflow enough to trigger the heater’s overheat safety shutoff within minutes of starting.

4. Check the Gas Supply

If the fan runs but produces no heat, check that gas is actually getting to the unit:

  • Check a gas hotplate or oven — if those work, the gas supply is fine and the issue is in the heater itself
  • Check the gas meter isolation valve (usually at the meter box on an external wall) is fully open — parallel to the pipe = open, perpendicular = closed
  • If you’ve recently run out of LPG (bottle gas setups in regional parts of Officer, Pakenham), arrange a refill
Safety warning: If you smell gas near the heater or anywhere in the house, do not attempt to relight the pilot or check the unit. Turn off the gas at the meter, ventilate the house by opening windows and doors, leave, and call the Victorian gas emergency line: 132 771 (24/7). Do not use light switches, mobile phones, or anything that could create a spark inside the building.

5. Look Up the Fault Code

Modern ducted heating controllers (Brivis, Braemar, Rinnai, Pyrox, Bonaire, Carrier) display fault codes when a sensor or component fails. Find the fault code in the owner’s manual — manufacturers also post fault code tables online for most models. Common codes:

Typical Code Common Meaning DIY Fix?
Filter/F codes Filter restriction detected Yes — clean filter immediately
Limit/overheat codes Thermal cutout triggered — usually a blocked filter or failed fan Clean filter first; if it persists, call a tech
Ignition fault codes Failed to ignite after 3 attempts Check gas supply; beyond that, call a gas technician
Pressure switch codes Airflow issue or pressure switch failure Call a licensed HVAC technician
Sensor fault codes Temperature or flue sensor reading out of range Call a licensed HVAC technician
Flame failure codes Burner lit but flame sensor can’t confirm — dirty flame sensor or gas issue Call a licensed gas technician
Cross-referencing a fault code in the owner's manual
Cross-referencing a fault code in the owner’s manual — most Brivis, Braemar, and Rinnai fault codes resolve to one of six common causes, and the manual lists which codes require a licensed gas technician versus a DIY filter clean.

Zone Heating Problems

If only some rooms are heating while others stay cold, the problem is usually in the zone control system, not the heater itself:

  • Check zone settings on the controller — some controllers allow individual zones to be turned off or scheduled separately. Make sure the problem zone is set to “on.”
  • Stuck zone dampers — ducted systems use motorised dampers (butterfly valves) inside the ductwork to redirect airflow between zones. These can seize from lack of use, particularly after a long Melbourne summer. If a zone is consistently cold even when set to on, the damper motor may have failed. This requires an HVAC technician with access to the roof cavity or subfloor space.
  • Duct disconnection — flexible ductwork in roof cavities can work loose at joins, particularly in older homes. This is obvious from a roof inspection but requires a technician to reconnect safely.

When to Call a Licensed Gas Technician

In Victoria, gas work (including relighting pilots on some units, replacing gas valves, and servicing the burner assembly) must be performed by a gasfitter registered with the Victorian Building Authority (VBA). An unlicensed person working on gas appliances is illegal and voids your insurance.

Call a licensed technician — do not attempt DIY — if:

  • You can smell gas at any point
  • The igniter clicks repeatedly but the unit won’t light after checking the gas supply
  • The unit shuts off within seconds of starting (distinct from the filter-triggered shutdown that takes 2–3 minutes)
  • You see fault codes related to pressure switches, sensors, or flame failure that persist after a filter clean
  • The heat exchanger area shows visible soot, rust, or the unit is more than 15 years old and hasn’t been serviced
Safety warning: A cracked heat exchanger is a serious carbon monoxide risk. Symptoms in the household — morning headaches, dizziness, or the carbon monoxide detector alarming when the heater runs — should be treated as an emergency. Turn off the heater, leave the house, ventilate, and call a licensed gas technician before using the heater again. Carbon monoxide is colourless and odourless.

Typical Repair Costs in Melbourne (2026)

Repair Type Typical Cost Notes
Callout / diagnostic fee $120–$250 Usually credited against repair cost if you proceed
Igniter replacement $180–$350 Common on units 8–15 years old
Gas valve replacement $350–$600 Includes parts and labour
Zone damper motor $250–$450 per zone Access difficulty in the roof affects price
PCB / controller board $400–$800 Expensive — compare to a new unit’s cost if heater is over 15 years old
Annual service (preventive) $150–$250 Strongly recommended every 1–2 years
Full system replacement $3,500–$8,000+ Depends on home size and zone count
Pro tip: Most Melbourne HVAC companies run a pre-winter service push from April to June — book an annual service in March (before the rush) to get a better appointment window and avoid paying emergency callout rates when the heater breaks on a cold July morning.

Tips and Gotchas

  1. Don’t reset fault codes by cutting power. On most modern controllers, turning the power off and on clears the fault display but doesn’t fix the underlying problem — it will fault again in the same way. Read the code first.
  2. Clean the filter more often than you think. Most manufacturers say “once a year” but Melbourne’s dust and pollen levels mean every 6–8 weeks during winter is realistic for a house with carpeted rooms or pets.
  3. The return air grille is not the only filter location. Some Brivis and Braemar units have a secondary filter at the heater itself, in the roof cavity. Check both if your model has one — the owner’s manual identifies filter locations.
  4. Zone dampers fail silently. A damper that sticks half-open gives you reduced airflow in two zones rather than obviously failing in one — you may just think “that room is always a bit cold” without realising it’s a fixable fault.
  5. Thermostat batteries go flat in winter. Wireless zone controllers are battery-powered. A faint or blank display during peak winter use is almost always flat batteries — keep a spare set of AA or AAA cells in the remote’s drawer.
  6. Cold air from vents doesn’t always mean the heater is broken. Many systems have a “cool start” delay of 2–4 minutes where the fan runs before the burner reaches temperature. This is normal — cold air from vents only becomes a problem if it continues for more than 5 minutes after the heater starts.
  7. Don’t run your heater without a filter installed. If the filter is being washed and dried, don’t run the unit — dust drawn directly into the heat exchanger and fan motor causes long-term damage.
  8. Get quotes from at least two licensed gas fitters. Callout rates and repair pricing vary widely across Melbourne. A second opinion is especially worth getting for PCB replacements or heat exchanger repairs, where the repair cost approaches the price of a new unit.
Comparing a clean filter (held up) with a clogged one on the floor
Comparing a clean filter (held up) with a clogged one on the floor — a fully blocked filter restricts airflow enough to cause the heater’s thermal safety switch to trip within minutes, making the unit appear broken when the fix is a 10-minute clean.

Frequently Asked Questions

Why does my ducted heater turn on and then immediately shut off?

If the unit starts and shuts off within 2–4 minutes, the most common cause is a blocked return air filter triggering the thermal safety switch. Clean or replace the filter first. If it still shuts off quickly with a clean filter, the fan motor may have failed or there is a fault with the heat exchanger limit thermostat — call a licensed HVAC technician.

My ducted heater is blowing cold air — what’s wrong?

Cold air from vents is normal for the first 2–4 minutes while the heat exchanger warms up. If cold air continues beyond 5 minutes, the burner has likely failed to ignite — check that the gas supply is on, the pilot light is lit (on older units), and there are no fault codes on the controller. Persistent cold air with gas on and no fault code usually means an ignition fault requiring a gas technician.

How often should ducted gas heating be serviced in Melbourne?

Energy Safe Victoria recommends servicing gas heating appliances every 2 years. In practice, most Melbourne HVAC technicians recommend annual servicing — particularly for units over 8 years old or in homes with pets and high dust levels. Annual servicing costs $150–$250 and catches filter issues, igniter wear, and heat exchanger condition before they cause a winter breakdown.

Can I relight the pilot light on my gas heater myself?

On older standing pilot models, the owner’s manual usually includes pilot lighting instructions you can follow safely. On modern electronic ignition units (which most post-2005 heaters are), there is no standing pilot — the igniter fires automatically. If you have an electronic ignition unit, “relighting the pilot” is not a DIY task — you’ll need a licensed gas fitter to inspect the ignition system.

What does it cost to repair a ducted heater in Melbourne?

Callout and diagnostic fees typically run $120–$250 in Melbourne, credited against the repair cost if you proceed. Common repairs range from $180–$350 for igniter replacement to $350–$600 for a gas valve and $400–$800 for a PCB (control board). For units over 15 years old, compare repair costs against a full replacement ($3,500–$8,000+) — a $600 repair on a 15-year-old heater often only delays an inevitable replacement by 1–2 seasons.

My heater is showing a fault code but I can’t find the manual — what should I do?

Search the brand name plus model number plus “fault code” online — most Australian HVAC manufacturers (Brivis, Braemar, Rinnai, Pyrox, Bonaire) have downloadable manuals and fault code tables on their websites. If you can’t find the model number, it is usually on a label inside the heater cabinet door or on the controller itself. Take a photo of the fault code display before calling a technician so you can describe it accurately.

Local Melbourne Resources

  • Replacement filters: Bunnings — foam return-air filters, or bring your old filter’s dimensions to get a match cut. Also check Mitre 10 for filter media by the metre.
  • Gas emergency (Victoria): 132 771 — Multinet Gas / Australian Gas Networks, 24/7
  • Licensed gas technicians (VBA register): Check that your technician holds a current licence at vba.vic.gov.au before they start work
  • Owner’s manuals: Brivis (brivis.com.au), Braemar (braemar.com.au), Rinnai (rinnai.com.au), Pyrox, Bonaire, Carrier
  • Energy Safe Victoria: energysafe.vic.gov.au — gas heater safety requirements and service recommendations