Skill level: Beginner | Time: 30–45 minutes | Cost: $0–$40 for filter replacement; $120–$200 for professional service
Quick Answer
Before Melbourne’s coldest weeks arrive, check your gas heater’s air filter, clear all supply vents and return air grilles, test ignition, and confirm the flame is burning blue. These checks take under an hour and cost nothing — but they sit alongside (not instead of) an annual professional service by a licensed gasfitter, which is strongly recommended for any gas heating system operating in Victoria.
July is when Melbourne’s gas heaters really earn their keep — and when the faults that went unnoticed through spring suddenly become urgent. A heater that won’t start at 6 am on a 5°C morning in Berwick or Pakenham isn’t just uncomfortable; it can also mean a service call during peak winter demand, when licensed gasfitters are booked out for weeks.
The good news is that most winter heater failures have early warning signs — weak airflow, unusual smells, delayed ignition, or a flickering flame — that a homeowner can spot in a 30-minute check before the cold sets in. This guide walks you through exactly what you can check yourself, what should only be done by a licensed professional, and the warning signs that mean you need help now rather than later.
This guide applies to the most common gas heater types across SE Melbourne homes: ducted gas central heating (floor or roof cavity units), wall furnaces (often found in older 1970s–1990s homes in Frankston and Mornington), and freestanding gas space heaters. Split-system heat pumps (reverse-cycle air conditioners) are electric, not gas, and are not covered here.
What You’ll Need
Tools
| Tool | Cost | Where to Get It |
|---|---|---|
| Torch (LED flashlight) | Already have / $15–$25 | Most hardware stores |
| Vacuum cleaner with brush attachment | Already have | — |
| Flat-head screwdriver | Already have | — |
| Replacement air filter (if needed) | $15–$40 | Your heater brand’s supplier, Reece Plumbing, or local HVAC supplier |
| Gas leak detector spray (optional) | $10–$20 | Mitre 10, Total Tools |
| P2 dust mask | $5–$10 | Most hardware stores |
Why This Check Matters in Melbourne
Melbourne’s south-eastern suburbs have some of the highest proportions of gas ducted heating of any region in Australia, and a large proportion of that stock is ageing. Many homes in Dandenong, Narre Warren, and Cranbourne have original 1990s ducted heating systems that may not have been serviced since last replaced. Gas Energy Safe Victoria (ESVA) receives thousands of callouts each winter for gas heater faults, many of which could have been caught earlier with basic seasonal checks.
Ducted gas systems also accumulate dust in their filters and ductwork over the warmer months — and a blocked filter forces the heat exchanger to run hotter than designed, which shortens its life and, in serious cases, can cause cracking that allows combustion gases to enter the home. The pre-winter filter check is the single most important thing you can do to protect both the equipment and your family.
Step-by-Step: Gas Heater Pre-Winter Check
Step 1: Check for Gas Odours Before Touching Anything
Before you touch the heater, stand near it and at the gas meter and take a sniff. Natural gas and LPG are odourless, but your gas supplier adds a rotten-egg smell (mercaptan) so that leaks are detectable. If you can smell gas — even faintly — do not proceed with any checks. Do not turn on lights, use your phone near the unit, or operate any electrical switch. Leave the building, call the Gas Emergency Line (1800 GAS GAS / 1800 427 427), and wait outside for the gasfitter to arrive.
If there is no gas smell, proceed with the rest of the check. You can also use a gas leak detector spray on the fittings at the back or base of the unit — spray it on connections and watch for bubbles, which indicate a leak.
Step 2: Inspect and Clean the Return Air Filter
On ducted gas heaters, the return air filter is usually located behind a grille panel on the front or side of the floor unit, or behind a ceiling return air vent. On wall furnaces, there is often a removable front grille with a mesh filter behind it. Locate your filter, remove it, and hold it up to a light source.
A lightly dusty filter is normal and can be cleaned by vacuuming from both sides using a brush attachment. A filter that is grey, matted, or clogged should be replaced. Dirty filters reduce airflow, cause the heat exchanger to overheat, and raise your running costs significantly — a blocked filter can increase gas consumption by 10–15% compared to a clean one.
Check the filter housing for dust buildup too — vacuum out the cavity before inserting a replacement. If the housing itself shows signs of rust or corrosion, note it for the gasfitter during the next service.
Step 3: Clear All Supply Vents and Return Air Grilles
Walk through every room and check that all supply vents (floor or ceiling registers that blow warm air) are open and unobstructed. Furniture, rugs, curtains, and stored items are the most common culprits. A partially blocked duct system forces the heater to work harder and can cause zones to underperform.
For the return air grille (usually a large louvred panel near the main unit), remove it and vacuum the duct behind it — this is where the bulk of household dust accumulates. Use your torch to check for any foreign objects, nesting material (mice are common in SE Melbourne homes near paddocks), or visible duct damage.
Step 4: Test Ignition and Observe the Flame
Turn your heater on at the thermostat and wait for ignition. On modern ducted systems, you should hear a clicking sound (the electronic ignitor) followed by the sound of the burner lighting within about 5 seconds. Some older systems have a standing pilot light — check the manufacturer’s label for your model’s ignition type.
Once the heater is running, locate the flame observation window (usually a small glass or mica window on the burner box, or you can open an inspection panel on some models — check your manual). The flame should be:
- Blue with small inner cone — normal, clean combustion
- Mostly blue with small yellow tips on the outer edge — acceptable
- Yellow, orange, or lifting off the burner — abnormal; switch off and call a licensed gasfitter
Step 5: Check the External Flue Outlet
Your gas heater exhausts combustion gases through a flue (also called a balanced flue or room-sealed flue on modern systems) that exits through an external wall or roofline. Go outside and locate the flue outlet — it is usually a round or rectangular grille on the exterior wall or a pipe above the roofline.
Check that the flue is not obstructed by:
- Bird nests or debris in or around the grille
- Vegetation that has grown over the outlet
- Paint or render that has partially blocked the vents (common in renovated homes)
- Signs of soot or discolouration around the outlet (normal is light grey; heavy black staining suggests combustion problems)
Step 6: Test the Thermostat and Timer
Set the thermostat to 22°C (higher than your current room temperature) and confirm the heater turns on and runs continuously until the room warms. Then raise it to 25°C, let the room reach that temperature, and confirm the heater cycles off. If the thermostat is not shutting the heater off correctly, the system will overheat the space and run up your gas bill significantly.
If your system has a programmable timer, reset it for the new season — many homeowners forget their summer “off” overrides and wonder why the heating isn’t running in the morning.
Step 7: Note Any Unusual Noises or Smells While Running
With the heater running normally, listen for:
- Loud banging when first igniting — often delayed ignition (gas builds up before lighting); needs a gasfitter
- Rumbling or vibrating — common in older units with worn fan bearings; note it for service
- Rattling from supply vents — usually a loose vent cover; press the grille to confirm and tighten screws
- Burning dust smell on first use — normal for the first 1–2 runs after a long off period; the smell should clear after 10–15 minutes
- Persistent burning smell or acrid odour — switch off and investigate; potential wiring or fan motor issue
Troubleshooting: Common Problems and What to Do
| Problem | Likely Cause | Action |
|---|---|---|
| Heater won’t ignite at all | Pilot light out (older units), faulty electronic ignitor, gas supply interrupted | Check gas meter is on; re-light pilot if instructed in manual; otherwise call a licensed gasfitter |
| Yellow or orange flame | Dirty burner, incorrect air-to-gas ratio, combustion problem | Switch off immediately — do not use until inspected by a licensed gasfitter; check for CO |
| Heater runs but airflow is very weak | Blocked air filter, blocked return air duct, fan fault | Clean or replace filter first; if flow is still weak after cleaning, call a heating technician |
| Loud bang on startup (delayed ignition) | Gas build-up before ignition due to dirty or faulty ignitor or burner | Do not ignore — switch off and have a licensed gasfitter inspect burner and ignition system |
| Heater runs but rooms don’t warm up | Blocked supply vents, thermostat fault, duct leaks, undersized system | Check all vents are open; test thermostat; have a heating contractor inspect ductwork |
| Gas smell when heater runs | Gas leak at connections or heat exchanger crack | Switch off immediately; evacuate; call 1800 427 427 |
When to Call a Licensed Gasfitter
In Victoria, all gas work — including internal servicing, burner cleaning, flue adjustments, and gas line connections — must be carried out by a licensed gasfitter registered with Energy Safe Victoria (ESAV). This is not optional: unlicensed gas work is illegal and can void your home insurance.
The DIY checks in this guide cover only what any homeowner can safely do: filter cleaning, vent clearing, visual inspections, and operational tests. Call a licensed gasfitter for:
- Annual professional service (strongly recommended every 2 years; annually for older systems)
- Any yellow or orange flame
- Delayed ignition or banging on startup
- Any suspected gas leak
- Flue adjustment, replacement, or extension
- Burner cleaning or heat exchanger inspection
- Carbon monoxide testing (a licensed gasfitter carries a CO analyser)
A standard ducted gas heater service by a licensed gasfitter in Melbourne costs approximately $120–$200, including cleaning the burner, checking the heat exchanger, testing CO output, and verifying the flue. It’s money well spent before a 5°C night in Pakenham.
Tips and Gotchas
- Buy a carbon monoxide detector. Gas heaters are the leading cause of CO poisoning in Australian homes. A basic detector costs $30–$60 and should be mounted near the sleeping area and near the main heater return air. Replace the battery at the start of each heating season.
- Don’t skip the filter because the heater “seems fine”. A blocked filter reduces airflow before it reduces heating performance — by the time the house is notably less warm, the heat exchanger has been running hot for weeks. Check the filter every April–May without fail.
- Check ventilation clearances if you’ve added furniture or a new room divider. Return air grilles need 300mm minimum clearance; supply vents need at least 150mm. Furniture pushed against a return air vent is one of the most common causes of heat exchanger overheating calls in SE Melbourne.
- Don’t use aerosol cans near an open-flame gas heater. Wall furnaces without glass panels (common in older Frankston and Mornington homes) have exposed flames. Aerosol cleaning products, spray paints, and deodorants near an open-flame heater have caused fires.
- The gas emergency line (1800 427 427) is free and available 24/7. Many homeowners don’t know this number — save it in your phone before you need it.
- Older wall furnaces may not have a flame failure device (FFD). If the pilot light blows out on pre-1996 wall furnaces, gas can continue to flow. If you have an older wall furnace that doesn’t have an automatic shutoff when the flame goes out, have it assessed — it may need replacing.
- Run the heater for 15 minutes on first use of the season. The first run clears accumulated dust from the heat exchanger and ducts. Open a window slightly to ventilate while it burns off — the burning-dust smell is normal but can be unpleasant.
- Gas heaters serviced in summer are cheaper and faster to book. If you missed the pre-season check, book a professional service in January–March when demand is lowest and gasfitters have better availability and sometimes off-peak pricing.
FAQ
How often does a gas heater need to be professionally serviced in Victoria?
Energy Safe Victoria recommends having your gas heater serviced by a licensed gasfitter every two years as a minimum, or annually for systems more than 10 years old. In Victoria, gas heater servicing must be done by a licensed gasfitter registered with Energy Safe Victoria — this is a legal requirement, not just a recommendation. Many insurers will also ask for service records if you make a claim relating to a gas appliance fault.
Can I clean my ducted heater filter myself?
Yes — cleaning or replacing the return air filter is one of the few gas heater tasks that homeowners can legally and safely do themselves in Victoria. Remove the filter, vacuum from both sides, and reinstall; or replace it with a new filter of the same size. Everything else inside the unit — burner, heat exchanger, flue — must be left to a licensed gasfitter.
Why is my ducted gas heater blowing cold air?
The most common causes are: the thermostat is set below the current room temperature (so the heater is technically “off”), the gas supply is interrupted (check the gas meter isolation valve is open), the ignition has failed (listen for clicking), or the heat exchanger has overheated and triggered the safety limit switch. For the last case, the heater will restart after cooling — but if it keeps doing this, the cause (usually a blocked filter) needs to be addressed. If the fan runs but no heat comes out, call a licensed gasfitter.
My gas heater makes a loud bang when it starts. Is that normal?
No — a significant bang or “boom” on ignition is called delayed ignition and means gas is accumulating in the combustion chamber before the ignitor fires. It’s a safety concern that can damage the heat exchanger over time and is not a normal startup sound. Minor ignition clicks are normal; a bang you can feel in the floor is not. Switch off and have a licensed gasfitter inspect the ignitor and burner before continuing to use the heater.
What colour should my gas heater flame be?
A correctly burning gas heater flame should be predominantly blue, sometimes with small orange tips on the outer edges. A blue flame indicates complete combustion with a good air-to-gas ratio. A yellow or orange flame indicates incomplete combustion, which produces carbon monoxide as a byproduct. If your flame is yellow, switch the heater off and contact a licensed gasfitter — do not continue using it until the cause is diagnosed and fixed.
Do I need a licensed gasfitter for a gas heater service, or can I do it myself?
In Victoria, any work on the gas components of a heater — including cleaning the burner, inspecting or adjusting the flue, checking the heat exchanger, or testing CO output — must be done by a licensed gasfitter registered with Energy Safe Victoria. It’s illegal to do this work yourself or to have an unlicensed person do it, and it can void your home and contents insurance if something goes wrong. The DIY checks in this guide (filter, vents, visual inspection, thermostat test) are all in the “air handling” part of the system and are safe for homeowners to do.
Local Melbourne Resources
- Energy Safe Victoria — Find a Licensed Gasfitter (verify your gasfitter’s licence before any gas work)
- Bunnings — Heating Air Filters (replacement filters, CO detectors)
- Mitre 10 — gas leak detector spray, CO detectors, replacement filters
- Reece HVAC-R — ducted heating filters and parts for Brivis, Bonaire, Rinnai, and Carrier systems
- hipages — Gas Fitters Victoria — get 3 quotes from licensed local gasfitters
Final Thoughts
The pre-winter gas heater check is one of the highest-value 30-minute jobs a Melbourne homeowner can do. A clean filter, clear vents, and a blue flame confirm the system is ready for winter; a yellow flame, a gas smell, or a bang on startup tells you there’s a problem that needs professional attention now rather than at 6 am on the coldest morning of the year.
The DIY checks above are genuinely simple — no tools beyond a vacuum and a torch are needed for most of them. What they can’t replace is the annual professional service: the gasfitter’s CO analyser, burner clean, and heat exchanger inspection are things you cannot do yourself, and for a gas appliance operating in a family home, that professional oversight matters. Book the service in summer if you can — better availability, better pricing, and one less thing to worry about when July arrives.
