Gas Ducted Heating Repairs VIC 2026 - Get Free Quotes

Carbon Monoxide and Why Victoria Takes It Seriously

This belongs at the top of any page about ducted gas heating, because it is the one fault that matters beyond comfort and cost. A gas heater burns fuel inside a sealed metal chamber called the heat exchanger, and the fan blows household air across the outside of that chamber, so the combustion products and the air you breathe are meant to stay entirely separate. That separation is the entire safety principle of the appliance. Everything else in a service is secondary to confirming it still holds.

A crack or a corrosion hole breaks that separation. Once the heat exchanger is compromised, combustion products including carbon monoxide can enter the airstream the fan is pushing through the ducts and into every room the system serves, which is what makes a ducted unit different from a single room appliance. A gas log fire affects one room; a ducted unit affects the whole house, including bedrooms where people sleep for eight hours at a time.

Carbon monoxide gives you no warning on its own. It has no colour, no smell and no taste, and the early symptoms are easily mistaken for something ordinary, with headaches, nausea, dizziness, tiredness and flu like feelings being the common presentation. In winter those are exactly the symptoms nobody investigates.

The pattern is what gives it away. Symptoms that appear when the heating is running and ease when the household is out or the heater is off, several people or pets in the house feeling unwell at the same time, and a problem that returns each winter and disappears each summer are all worth taking seriously. Pets showing the same pattern is a signal households frequently overlook. Animals spend more hours in the house than anyone else does, and a dog that seems flat all winter and fine all summer tells you something. Smaller bodies are affected sooner. Melbourne winters are long enough that small inefficiencies compound into real money.

Energy Safe Victoria recommends that gas heaters be serviced by a qualified person at least every two years, and that servicing includes testing for carbon monoxide. Guidance is published by Energy Safe Victoria, and health information sits with the Victorian Department of Health. The two yearly interval is a recommendation, not a suggestion to weigh against convenience.

If you suspect it, act before you investigate. Turn the heater off at the wall, open doors and windows, get everyone outside into fresh air, and seek medical advice if anyone is unwell, then arrange testing by a licensed gasfitter before the unit is used again. Do not run it again to see whether the symptoms come back. Confirming a suspicion that way is not worth what it risks, and a gasfitter with an analyser can answer the question properly in under an hour.

Testing is inexpensive and it is a specific procedure rather than a general look. A gasfitter with the right endorsement uses a calibrated analyser to measure carbon monoxide in the flue and in the room, checks the heat exchanger for cracking, and assesses whether combustion products are spilling, which is a different exercise from cleaning filters and checking the thermostat. Establish that the test is included before booking, since not every advertised service covers it.

Sealed Homes, Exhaust Fans and Flue Spillage

The second mechanism is less understood and it does not require a cracked heat exchanger at all. Open flued heaters draw combustion air from inside the room and vent the products up a flue, and that flue relies on the pressure balance inside the house being roughly neutral. Nothing about the appliance has to fail for that balance to be disturbed. A perfectly sound heater in a perfectly sound flue can still spill if the house around it has changed enough.

Modern homes are far more airtight than the ones these systems were designed around. Weather sealing, draught proofing, double glazing and tighter construction all reduce the air leaking in, and that changes the pressure conditions the flue depends on. The house has effectively changed around an appliance that has not.

Exhaust appliances then tip the balance. A rangehood, a bathroom exhaust fan, a clothes dryer or a ceiling exhaust running while the heater operates pulls air out of the house, and the easiest place for replacement air to come from can be back down the flue, dragging combustion products into the room with it. A rangehood on high in a sealed kitchen is a surprisingly powerful extractor. Commercial style rangehoods fitted during Melbourne kitchen renovations move several times the air of the units they replaced, and the flue has no way of competing with that.

That is depressurisation and it is a real and testable condition. A gasfitter can run a negative pressure test with exhaust appliances operating, which is exactly why a heater that tests clean in isolation may still spill under the conditions a household actually creates on a winter evening. Cooking dinner with the heating on is the exact scenario worth testing, because it is also the scenario that happens every night of winter. A test carried out with the house sealed and every exhaust appliance running tells you what your family is actually exposed to, rather than what the heater does under ideal conditions.

Renovations frequently introduce the problem years after installation. A new rangehood with much higher extraction, a bathroom refit with a stronger fan, or a draught proofing job can each change the pressure balance in a house whose heater has run safely for a decade, and nobody connects the two events. The heater is blamed and the renovation is not. Owners describe a system that worked perfectly for years and has suddenly become unreliable, which sounds like an appliance problem and frequently is not. Establishing what changed in the house is part of a proper diagnosis. On a system this age, one fault is rarely the only one present.

Room sealed and flueless units behave differently. A room sealed appliance draws combustion air from outside and discharges outside, which removes the dependency on indoor pressure, and it is one of the reasons open flued units attract more attention in servicing guidance. Establishing which type you have should happen before anything else. An open flued unit draws its combustion air from the room, a room sealed one does not, and every question about depressurisation only applies to the first. Your gasfitter can tell you in seconds. Getting that established early shapes every decision that follows.

Mention any recent renovation when you book a service. A gasfitter who knows a new rangehood went in last year will test with it running, and that single piece of information changes what the test is looking for. Say what changed and roughly when.

The Checks Worth Doing Before You Call

Start with the thermostat, because a surprising share of dead heaters trace back to it. Confirm it is calling for heat, check the mode is set to heating, and replace the batteries in a battery powered controller before assuming anything mechanical has failed. It resolves more callouts than anyone would guess. Wall controllers on ducted systems are frequently battery powered, and a flat battery produces a system that looks completely dead.

Check the gas supply is actually on. An isolation valve at the appliance turned off during other work, a gas meter valve closed, or an account issue at the retailer all produce a heater that turns over and never lights, and none of them need a tradesperson. Check the meter before you check anything else. Anyone who has had plumbing, kitchen or hot water work done recently should look at the appliance isolation valve too, since it gets closed during other work and left that way.

Look at the return air filter next. Ducted heating pulls household air through a return air grille and a restricted filter reduces airflow, which makes the unit run hotter, trip on a safety switch and shut down, and a filter that has never been cleaned is common on units in period homes where the return sits under the floor. Out of sight genuinely does mean out of mind on a subfloor return. Filters in that position can go a decade without anyone lifting the grille, and the restriction builds so gradually that nobody notices the heating getting worse until it stops altogether. Lifting it takes a screwdriver and two minutes. Owners consistently underestimate how much of this is preventable.

Note whether the unit does anything at all. Whether the fan runs without heat, whether it lights and then cuts out after a few minutes, whether it makes a noise and stops, or whether nothing happens at all are four different faults and the distinction saves diagnostic time. Write down exactly what happens and in what order.

Check the power as well as the gas. Ducted gas units need mains power for the fan and controls, so a tripped circuit or a switched off isolator at the unit produces a dead system that has nothing to do with gas at all. Look at the switchboard before assuming the worst, and any wiring question sits with electrical services.

Photograph the compliance plate while you are there. Make, model and serial number let a gasfitter check parts availability before attending, and on older units that single detail decides whether a repair is even possible. Keep the image, since it gets wanted at every future service.

Ignition, Gas Valves, Controls and Blowers

Ignition faults are the most common reason a ducted gas unit stops heating. Older systems use a standing pilot with a thermocouple, and newer ones use electronic ignition with a spark or hot surface igniter, and both wear out in ways that produce a unit that tries to light and gives up. Age of the unit tells you which type you are likely dealing with. Standing pilots were standard well into the 2000s, and electronic ignition dominates anything installed since.

A thermocouple that has aged is the classic version. It generates a small current proving the pilot is alight, and as it degrades it stops holding the gas valve open, so the pilot lights while you hold the button and dies the moment you release it. That symptom is close to diagnostic on its own. Thermocouples are inexpensive parts, so this is one of the cheaper faults a ducted gas unit can present with, provided the gasfitter can still source one for the model.

Electronic ignition failures look different again. A cracked hot surface igniter, a dirty flame sensor that cannot detect the flame it has just lit, or a control board fault all produce a unit that goes through its sequence, ignites briefly and locks out, frequently displaying a fault code to write down. Photograph the code before you cycle the power, since resetting clears it. Fault codes are model specific and a gasfitter can frequently identify the failed component from the code alone before attending, which means arriving with the right part instead of making a second trip. That single photograph can save you a callout.

Gas valve failures sit at the higher end of that cost range. The valve controls gas delivery to the burner and it is a safety critical component, so replacement is a licensed job with no room for improvisation, and on a unit past fifteen years the valve cost starts to argue for replacement of the whole appliance. Have both figures quoted together.

Blower motors fail gradually and they announce themselves. Bearings that have worn produce a rumble or a squeal that gets worse over weeks, a motor drawing too much current trips on thermal overload and restarts, and a failed capacitor leaves a motor that hums without turning. None of those improve on their own, and all get worse through a season. A bearing noise noticed in May is usually a failed motor by August, and motors are considerably easier to source outside the peak. Acting on a noise early is the cheapest version of that repair.

Overheating shutdowns are usually airflow rather than the unit. A high limit switch cutting the burner because the heat exchanger is getting too hot is the system protecting itself, and the underlying cause is nearly always a blocked filter, closed outlets, a collapsed duct or a failing fan restricting the air that should be carrying the heat away. Chasing the switch instead of the airflow is how money gets wasted here. Replacing a high limit switch on a system with a blocked filter produces a unit that overheats without protecting itself, which is worse than the original fault. The switch is doing its job.

Under Floor Units and Subfloor Ducts in Older Homes

Melbourne's housing stock puts a great many ducted gas units under the floor and not in the roof, and that is a distinctly Victorian arrangement worth understanding. Weatherboard and period brick homes on stumps have a subfloor void, and installers used it because it was the easiest route for ducts to reach floor outlets. Roof mounted units are more common in newer estates and on brick veneer homes, so the age and style of a Melbourne house is usually a fair guide to where its unit will be.

That location creates conditions the equipment never enjoys. Subfloors are damp, poorly ventilated in many older homes, and accessible to rodents and possums, so the unit and its ductwork sit in a corrosive and hostile environment for their entire life. Nothing about that changes over twenty years except that it gets worse.

Corrosion is the consequence that matters most. A heat exchanger in a damp subfloor corrodes from the outside as well as fatiguing from the inside, which is why age alone is a poor guide and why units in these positions deserve the two yearly carbon monoxide test rather than a longer interval. Location is a legitimate reason to service more often rather than less. A unit in a dry roof space and one in a wet subfloor face very different conditions over twenty years, even if the model and the install date are identical.

Ductwork under a floor takes physical damage constantly. Flexible duct gets crushed by anyone working under the house, disconnected at collars, chewed by rodents, and left sitting in water where subfloor drainage is poor, and each of those quietly removes heat from a room somebody is complaining about. None of it produces a fault code or a warning light.

A single disconnected run explains most cold room complaints. The duct discharges its entire airflow into the subfloor, so the room gets nothing while the system heats the ground under the house, and the owner assumes the unit is undersized. It is also one of the cheaper repairs once someone has actually looked. Reconnecting a duct at its collar and taping it properly is minutes of work, and the room it serves is transformed. The hard part is getting someone under the house to find it.

Subfloor moisture is worth addressing on its own merits. Poor ventilation under a period home damages ducts, accelerates corrosion and contributes to rising damp in the structure, and improving it sits with underfloor ventilation installation while damp assessment sits with rising damp assessment and repairs. Improving subfloor ventilation helps the heating, the ducts and the structure at the same time.

Vermin belong in the same conversation as the duct repair. Repairing chewed ductwork without excluding the animal produces the same damage again within a season, so pest control should run alongside the duct repair. Chewed wiring under a floor also produces intermittent faults that look like electronics failure.

Ductwork, Zoning and Rooms That Never Get Warm

A ducted system is only as good as the ducts, and they are the component owners never think about. Heat produced at the unit has to travel through insulated flexible duct to each outlet, and anything that restricts, leaks from or disconnects that path removes performance without producing any fault code. Ducts are invisible and silent, which is why they get ignored. Nobody has ever looked at a heating quote and asked about the duct condition.

Duct insulation degrades with age and it costs real money. An old run with compressed or damaged insulation loses heat into a subfloor or roof space along its length, so the air arriving at the outlet is cooler than what left the unit and the system runs longer to compensate. That shows up on the bill rather than as a complaint, which is why duct insulation should be checked on any system over fifteen years old. Melbourne's heating season runs long enough for the difference to be material.

Crushing is the most common physical fault. Duct squashed under stored boxes, kinked around a tight corner at installation, or flattened where someone crawled over it delivers a fraction of its design airflow, and the room served by that run is the one everybody complains about. Duct needs to run reasonably straight and be supported at intervals.

Return air is the half that gets undersized. A ducted system needs a return path as generous as the supply, and a restricted return strangles an otherwise healthy unit, producing weak airflow at every outlet and high limit shutdowns that look like a unit fault. It is a design fault, which is why servicing never resolves it.

Zoning adds a rule households forget. Systems with zone dampers usually require a minimum number of zones open, and running with only one small zone forces the full fan output through a fraction of the outlets, which makes them noisy and can trip the unit out on temperature. Establish the minimum open zone requirement for your particular system.

Balancing outlets is cheap and it is rarely done. Adjusting outlet dampers so each room gets a fair share of the available air resolves a great many complaints about one cold bedroom without touching the appliance, and general duct cleaning scope sits with air conditioning duct cleaning and sanitisation. Have balancing included in the service rather than quoted separately.

Flues, Cowls and What Sits on the Roof

The flue is the part of a ducted gas system nobody inspects and it does a job the appliance depends on entirely. It carries combustion products from the heat exchanger out of the building, and its condition, its termination and what has been built near it all affect whether that happens properly. It is the one component that is genuinely out of sight.

Corrosion is the common finding on older flues. Metal flue pipe rusts from the inside where combustion products condense, particularly on units that cycle frequently in Melbourne's shoulder seasons, and a flue that has holed lets products escape into a roof space instead of leaving the building. From there it can find its way back into the house.

Terminations get compromised by later work. A cowl that has blown off, a flue shortened during a roof replacement, a solar panel or a new addition built close enough to disturb the discharge, or vegetation grown over an external termination will each affect how well the flue clears. Clearances around a termination exist for a reason.

Birds and vermin block flues with alarming regularity. A nest in a flue over summer is discovered on the first cold morning when the heater lights, spills and locks out, and it is one of the more common seasonal callouts across Melbourne every May. A quick look up at the termination in autumn costs nothing.

Roof work is where flues get damaged without anyone noticing. A restoration, a re-bed and repoint, or a solar installation all involve people working around a flue termination, so a heater that behaved perfectly last winter and now spills should be connected to whatever happened on the roof since. Related work sits with roof repairs. Anyone on your roof should know a gas flue is there. Mention it to roofers, solar installers and antenna technicians before they start, since none of them are looking for it and all of them work around it. A displaced cowl is easy to cause and easy to miss.

Mention any roof work when you book. A gasfitter told that the roof was restored in autumn will look at the termination first, and that single detail can save an hour of diagnosis on a fault that has an obvious cause once someone knows to look for it. Timing is the clue and owners are the only ones who have it.

Signs a Unit Is Approaching the End

Ducted gas units give reasonable warning if you know what to watch, and the signals appear well before the appliance stops. Rising gas bills without any change in how the heating is used, longer run times to reach the same temperature, and rooms that used to be comfortable now needing the thermostat pushed higher all point the same way. None of them are dramatic and all of them are measurable. Comparing a winter gas bill against the same quarter two years earlier is the simplest version of that check.

Flame appearance is the clearest visual indicator on units where the burner is visible. A healthy gas flame burns blue and steady, while yellow, lazy or flickering flames suggest incomplete combustion, and incomplete combustion is what produces carbon monoxide in the first place. If you can see the burner, look at it once a season.

Sooting is the same message written on the appliance. Black deposits around the unit, on the flue or near outlets indicate combustion that is not happening cleanly, and it warrants a gasfitter. Cleaning it away removes the evidence and not the cause. Photograph it before touching anything, since a gasfitter will want to see where it was.

Smells belong in a category of their own. A burning dust smell in the first few minutes of the season is normal and clears quickly, while a persistent acrid or chemical smell, or a smell of gas at any time, is a stop and call situation, and a gas smell means shutting the supply off and contacting gas leak repairs immediately. Do not use switches or anything that could create a spark.

Noise changes should be logged as they develop. A rumble that has appeared over a few weeks, a bang on ignition that was never there before, or a rattle that comes and goes are all telling you a component is wearing, and catching that early is the difference between a part and an appliance. Note when a noise started, since duration matters.

Twenty years is a realistic upper bound for most ducted gas units. Beyond that, parts support thins out, efficiency lags well behind current models and heat exchanger condition becomes the dominant question, so planning a replacement on your own timetable beats being forced into one in July. Quotes obtained in summer are also cheaper and easier to compare.

Repair or Replace

Age and the failed component decide this together, and the heat exchanger is the item that usually ends the conversation. A cracked exchanger on a unit under warranty is a manufacturer matter, while the same fault on a fifteen year old appliance means spending $1,200 to $3,500 on a component inside a machine whose other parts are the same age. That comparison is the honest way to frame the decision.

Parts availability is the practical constraint on older units. Manufacturers support models for a defined period, and once a control board or a gas valve is no longer produced, a repair that would have been straightforward becomes impossible regardless of what anyone is willing to pay. Check parts availability before authorising any diagnosis on a very old unit.

Efficiency has moved considerably and it shows up on the bill. Older ducted gas units were built to lower star ratings than current models, so a household running a twenty year old appliance through a Melbourne winter is paying a premium every month that partly offsets the cost of replacement. Compare running cost as well as purchase price.

Existing ductwork is frequently reusable and that changes the numbers. Where the ducts are sound, a replacement unit connects to what is already there, which is why replacement quotes vary so widely and why any quote should state clearly what happens to the existing duct runs. Reusable ducts can take thousands off a replacement figure. A quote that assumes full duct replacement without inspecting what is there is guessing high, and one that assumes reuse without looking is guessing low. Have the assumption stated either way.

Victoria has also changed the rules for new homes, and it affects how people think about replacement. Gas connections are no longer permitted in certain new residential builds under state planning provisions, which does not require anyone to remove a working system but does shape the long term view, with general information published by the Victorian Government. Existing homes are not affected by that change.

Reverse cycle is the alternative most households compare against. It heats and cools from one system, runs on electricity and suits a home with solar, while ducted gas delivers heat quickly and suits households used to it, and the honest comparison depends on your existing ductwork, your electricity arrangement and how long you plan to stay. Options sit with reverse cycle air conditioning and air conditioning replacement and upgrade. Get both a like for like gas quote and a reverse cycle quote before deciding. The two systems suit different households and the honest answer varies, so a contractor who only ever recommends one of them deserves a second opinion. Running cost projections should use your own usage figures.

Licensing, Compliance Certificates and Contracts

Gasfitting is licensed work in Victoria and the requirements are specific. A person carrying out gasfitting, the trade covered under gas fitting, must hold the appropriate licence or registration, and servicing a Type A gas appliance such as a ducted heater requires the relevant appliance servicing endorsement rather than a general gasfitting ticket alone. The distinction is not a technicality. Servicing a Type A appliance requires specific training and equipment, and the endorsement is what confirms someone has both.

Find out which endorsement the person holds. It is a fair question, the answer is checkable, and a general plumber without the Type A servicing endorsement is not the right person to carry out a carbon monoxide test on your heater. Any properly qualified business answers that question immediately.

Compliance certificates are the paperwork that proves the work. Gasfitting work in Victoria requires a compliance certificate to be issued, and it is the document you will want at resale, in any warranty claim and if a question about the work ever arises, so request it rather than waiting to be offered one. File it with the appliance manual. Compliance certificates are frequently requested during a sale, and reproducing one years later is far harder than keeping the original. Scanning it takes a moment and it outlasts paper.

Servicing standards are published rather than invented. AS 4575 covers the servicing of Type A gas appliances and AS 5601 covers gas installations, both published through Standards Australia, and a gasfitter should be able to tell you what their service covers against that framework. A service with no reference point is difficult to compare between contractors.

Building practitioner registration applies to larger work. Domestic building work above the relevant threshold requires a registered practitioner and domestic building insurance, with registration administered by the Building and Plumbing Commission and consumer guidance published by Consumer Affairs Victoria. Registration can be checked before any deposit changes hands, and it takes about a minute on the public register.

Disputes about domestic building work go to the Victorian Civil and Administrative Tribunal, with information published by VCAT. Australian Consumer Law guarantees apply on top of any contract, requiring work to be carried out with due care and skill, and guidance sits with the Australian Competition and Consumer Commission. Those rights sit on top of any manufacturer warranty.

Working in a subfloor or a roof space brings its own obligations. Confined space conditions, poor ventilation, live wiring and dust are all present in the places these units live, and requirements are published by WorkSafe Victoria. That alone is a strong argument against having a look yourself.

Rental Properties and Owners Corporations

Victoria sets specific obligations for rental properties and gas heaters feature in them. Rental providers have duties around the safety and maintenance of gas appliances supplied with the premises, including checks by a qualified person at defined intervals, and guidance is published by Consumer Affairs Victoria. Rental providers should diarise the interval, because the obligation attaches to the property whether or not anyone has thought about it that year.

Renters should report symptoms in writing and keep a copy. Headaches or nausea that coincide with the heater running, a pilot that will not stay lit, sooting around the unit or a yellow lazy flame where it should be blue are all worth reporting immediately and not at the next inspection. Put it in writing and keep a copy of what was sent. A dated message establishes when the issue was raised, which matters if the response is slow.

A suspected carbon monoxide problem is urgent rather than routine. Turn the appliance off, ventilate, and report it as an urgent matter, because this is not a situation to leave pending while the usual repair process runs its course. Say plainly in the report that you suspect carbon monoxide.

Rental providers are better off scheduling the checks proactively. Booking gas safety checks across a portfolio in the warmer months means availability, normal pricing and documentation in place before the heating season starts. Agents managing multiple properties can book them together.

In an owners corporation the split depends on where the equipment sits. A unit serving a single lot is generally the owner's, while flues, shafts and any plant on common property can involve the owners corporation, and the plan of subdivision and rules are what settle it. Check before arranging your own contractor on shared plant.

What to Look Out For

Start with the carbon monoxide question. A service that does not include a carbon monoxide test is not the service Energy Safe Victoria recommends, so confirm the test is included, what equipment is used and whether you receive the readings in writing. A verbal assurance that it tested fine is not a record. Readings in writing also give you a baseline to compare against at the next service.

Be cautious of a quote to replace a heat exchanger on an old unit without a replacement comparison. That component sits between $1,200 and $3,500 inside a machine whose other parts are the same age, and any honest contractor will put both numbers in front of you before you decide. If only one figure is offered, request the other before deciding. A contractor confident in the repair recommendation will have no difficulty providing both.

Watch for a diagnosis reached without anyone accessing the unit. On a ducted system the appliance, the ductwork and the return air all sit under the floor or in the roof, so a technician who has looked only at the thermostat has inspected the smallest part of the system. Find out whether they accessed the unit and the ductwork.

Check whether a replacement quote addresses the ducts. New equipment connected to crushed, disconnected or poorly insulated ductwork underperforms, and the owner is left wondering why an expensive upgrade delivered so little warmth. Have the duct condition stated in the replacement quote.

Finally, confirm the licence and the compliance certificate. Type A appliance servicing endorsement and a compliance certificate for the gasfitting work are both standard, and any established business provides them without hesitation. Both are checkable and neither is an unreasonable request.

How to Get Useful Quotes

Photograph the compliance plate on the unit and send it. Make, model, serial and approximate age let a gasfitter check parts availability and known faults before attending, and on an older appliance that determines whether a repair is possible at all. Send it with your first message. It is the single most useful thing you can provide and it takes seconds.

Describe the symptom precisely and in sequence. Whether the unit does nothing, whether the fan runs without heat, whether it lights and cuts out after a few minutes, whether it locks out with a code, and how long the pattern has been happening. Say whether it started suddenly or developed over weeks, since a sudden failure and a gradual decline point at different components entirely.

Say where the unit is and how it is reached. Under the floor, in the roof space, in a cupboard or externally, and whether the subfloor is crawlable or the roof space is walkable, because access is the largest single variable in the labour cost. Say whether the subfloor has a hatch and how tight the space is.

Mention anything that changed. A new rangehood, a bathroom exhaust upgrade, draught proofing, a renovation, work under the house, or new flooring over a floor outlet can each affect how the system performs and whether a flue spills. Approximate dates matter more than exact ones.

Have each quote confirm whether a carbon monoxide test is included and how it is reported, what the callout covers and whether it is credited against the repair, part numbers and prices before ordering, what happens to the ductwork, and which licence and endorsement apply. Answering those makes the quotes comparable. A callout fee alone tells you almost nothing about the final figure. Whether it is credited against the repair matters more than what it is.

Servicing and What Actually Prevents Problems

Book the service at least every two years and put a reminder somewhere you will see it. That is the interval Energy Safe Victoria recommends for gas heaters, it includes the carbon monoxide test that nothing else replaces, and it is the single most useful thing an owner of ducted gas can do. Nothing else on this list comes close in value. A service catches the faults that matter before they become failures, and it is the only thing on the list that tests for carbon monoxide at all. Everything else is comfort and running cost.

Schedule it outside the rush. February through April gives you availability, normal pricing and time to order any part that turns out to be needed, and it means the system is proven before the first cold snap rather than during it. Booking in autumn is genuinely cheaper as well as easier.

Clean the return air filter several times through the heating season. It is the cheapest maintenance available, it prevents the overheating shutdowns that look like unit failures, and on a subfloor return it is frequently the item nobody has touched in years. Buy a spare so one can dry while the other is in use. Filters have to be completely dry before going back, and having two removes the temptation to refit a damp one. A few dollars buys you a season of better performance.

Keep floor outlets clear of furniture and rugs. Blocking outlets raises pressure in the system, starves rooms of heat and contributes to high limit trips, and it is a common finding in period homes where furniture placement was decided long after the heating went in. Rugs over floor outlets are the version people forget entirely.

Have the ductwork looked at when anyone is under the house. Anybody attending for plumbing, wiring or pest work is already in the space where the ducts live, and asking them to note anything disconnected or crushed costs nothing. Broader electrical work sits with a local electrician and general upkeep with handyman services. Take a photograph of anything that looks wrong under there.

Reduce the load on the system and it runs less hard for the same result. Ceiling insulation, sealing gaps around doors and windows and closing off unused rooms all cut the heat the unit has to produce, and insulation work sits with ceiling and wall insulation installation. A well insulated Melbourne home asks far less of its heating than a poorly insulated one.