A gas heater does not usually fail loudly. It drifts, and the two things that drift first, combustion quality and the safety devices meant to catch it, are the two things you cannot see from the couch.
A gas heater is one of the few appliances in a house that can be working perfectly from where you are sitting and still be worth looking at. The flame is on, the room is warm, and nothing about the experience tells you how cleanly the fuel is burning or whether the safety device behind the flame would still do its job.
That is the whole case for servicing, and it is why the interval question comes up so often. It is also why the answers people find online contradict each other. One page says every two years, another says annually, and a third says whenever it stops working.
Those answers are not actually in conflict once you know which one is a regulator’s floor and which one is a manufacturer’s instruction. Here is the difference.
The short version
- Have a domestic gas heater serviced at least every two years by a licensed gasfitter.
- Make it annual if the house is dusty, if you have pets, or if the heater runs hard through the season.
- Check your handbook. If the manufacturer says annually, annual is what applies to your appliance.
- Commercial kitchens and commercial appliances are a different cadence again, and we service those every six months.
- Gas work is licensed work in New South Wales. It is not a DIY job at any interval.
- Book a service on (02) 6652 2411.
Where the two year interval comes from
The figure almost everybody quotes traces back to Energy Safe Victoria, which is the energy safety regulator in that state. Its guidance on heating a home with gas states that “we recommend that all gas heaters are serviced at least every two years by a qualified gasfitter”.
That is a clear, published, regulator backed interval, which is why it has spread well beyond Victoria and become the default answer nationally.
What New South Wales actually says
Here is the part that surprises people. New South Wales does not publish an equivalent interval for domestic gas appliances. Its gas safety guidance takes a different approach and defers to the appliance instead: “It is recommended that appliances are serviced by a licenced gasfitter in accordance with the manufacturer’s specifications.”
So in this state the authority on how often your gas heater needs a service is the handbook in your kitchen drawer. If it says every twelve months, then twelve months is your interval, and a two year cycle would put you outside the manufacturer’s instructions and potentially outside your warranty.
What New South Wales is unambiguous about is who may do the work. The same guidance says to “always have a licensed gasfitter install, repair and service gas appliances”, and under the Gas and Electricity (Consumer Safety) Act 2017 gas work is licensed work rather than a matter of preference. Our gasfitting page covers what that licensing actually means, and our appliance installation page covers the certificate side of it when a new appliance goes in.
Why we put the two together
Read in combination, the two positions give you a rule that is easy to live with. Two years is the floor. The handbook is the instruction. Take whichever is more frequent.
In practice, for most homes on the Mid North Coast running a gas heater through a short and mild winter, a two yearly service is proportionate. The households where we would push for annual are the ones described below, and they are more common than you would guess.
The conditions that move it to annual
- Dust. A dusty house, a rural block, a building site next door or a recent renovation all load up a burner and a fan faster than normal.
- Pets. Animal hair is the single most effective way to block an air inlet, and a heater with a restricted air supply is a heater burning less cleanly.
- Heavy use. A heater that runs most of the day through winter is doing several times the work of one that comes on for two hours an evening.
- Age. Older appliances drift more, and their parts are closer to the end of their service life.
- Salt air. Coastal corrosion is a real factor here, particularly on flue components and external terminals.
- An appliance you have inherited. If you bought the house with the heater in it and have no service history, start with a service rather than assuming one.
Our gas heating page sets out the appliances we sell and service, and the full scope of what we look after is on our repairs and maintenance page.
Commercial is a different question entirely
A commercial appliance is not a domestic appliance that happens to be in a business. It runs longer hours, at higher output, in a harder environment, and when it stops the cost is not discomfort but lost trade.
We service commercial gas equipment every six months for that reason, and we attend commercial breakdowns on site within 24 to 48 hours. Commercial kitchens in particular accumulate grease and airborne fat in places a domestic heater never would, and that changes both the cleaning and the combustion picture.
Carbon monoxide, and why the interval exists at all
Everything above is really about one thing. A gas appliance burning properly produces carbon dioxide and water vapour. A gas appliance burning improperly can produce carbon monoxide, which has no colour, no smell and no taste.
The reason a service interval exists is that the shift from the first state to the second is gradual and invisible. A burner that has picked up dust, a heat exchanger developing a fault, a blocked or partially blocked flue, a fan that has lost airflow: any of these can degrade combustion without changing anything you would notice while the heater is running.
Carbon monoxide symptoms are also easy to misread, because headaches, tiredness, nausea and dizziness that come on indoors and ease when you go outside look a great deal like a winter virus. The Victorian Government’s Better Health Channel guidance on gas heating health and safety sets out the health side of this in more detail, and it is worth a read if anybody in the household has been unwell through winter without an obvious cause.
What to do if you suspect it
If you suspect carbon monoxide, turn the heater off, open doors and windows, get everybody into fresh air, and seek medical advice. Then do not use the appliance again until a licensed gasfitter has tested it. Not later in the week when it is cold again. Not on the low setting. Not at all.
We carry out a carbon monoxide test as part of every gas heater service we do, which is the only way to know where an appliance sits rather than guess.
The oxygen depletion sensor, and what it does not cover
Every gas heating unit we sell is fitted with an oxygen depletion sensor, usually shortened to ODS. It is a genuinely elegant piece of engineering and it is widely misunderstood, so it is worth explaining properly.
An ODS is built into the pilot assembly. The pilot flame is aimed precisely at a thermocouple, and that thermocouple is what tells the gas valve to stay open. If the oxygen level in the room drops, the flame changes shape and lifts away from the thermocouple. The thermocouple cools, the signal stops, and the gas valve shuts the appliance down.
So the sensor is not electronic and there is nothing to replace a battery in. It is the flame itself acting as the sensor.
What it is important to understand is what an ODS is not. It is not a carbon monoxide detector. It responds to falling oxygen, which is a good proxy for a room becoming unsafe, but it is not measuring carbon monoxide and it will not necessarily protect you against a flue fault on a flued appliance. It is one safety layer, and it is a layer that itself needs to be tested, because a pilot assembly that has drifted out of alignment or accumulated dust may not shut down when it should.
Testing that shutdown behaviour is part of a service. It is one of the clearest examples of something you cannot check yourself and would never notice was not working, right up until the moment you needed it.
Flued and unflued appliances are not the same risk
A gas log fire or gas fireplace is a flued appliance. Every gas log fire we install runs on a power flue, which means combustion products are actively vented outside the building, and the flue and its terminal become part of what needs checking.
A portable gas heater on a bayonet point is unflued, which means everything it produces stays in the room. That is why unflued portables are rated at under 25 megajoules per hour and why they come with ventilation requirements and a minimum room size in the manual. Those requirements are not padding. They are the mechanism by which the appliance is safe.
The minimum room size is not arbitrary either. The Australian gas installation standard sets it by room volume, at 0.4 megajoules per hour for every cubic metre of room in a thermostat controlled heater, and 0.2 megajoules per hour per cubic metre in a model without a thermostat. Multiply length by width by ceiling height to get the volume, then apply the figure. A room four metres by five metres with a 2.4 metre ceiling is 48 cubic metres, which allows a thermostat controlled portable of up to about 19 megajoules per hour, or a non thermostat model of under 10. If the heater on the showroom floor is rated higher than the room allows, it is the wrong heater for that room regardless of how well it heats.
If you use a portable, check the plate and the manual for the minimum room size, leave the ventilation the manufacturer asks for, and do not use it in a bedroom or a bathroom or any room with the door closed and no fresh air. Do not leave it running overnight either.
There is one more habit worth breaking, because very few people know about it. Do not run a rangehood or a bathroom exhaust fan while an unflued or open flued heater is going. An extraction fan in a reasonably well sealed house lowers the air pressure inside, and the easiest path for replacement air can be back down the flue, which draws combustion products into the room rather than sending them out of it.
What you are noticing, and what it usually means
Most service calls start with somebody noticing something small. This is the table we would hand over the counter, because knowing which of these means “book a service” and which means “stop using it” is genuinely useful.
| What you are noticing | What it usually means | Keep using it? |
|---|---|---|
| A smell of gas, at any strength | A leak at a fitting, hose, regulator or bottle | No. Turn the gas off at the bottle, do not use switches or flames, ventilate and call a licensed gasfitter |
| Headaches, nausea or tiredness that ease when you go outside | Possible carbon monoxide from poor combustion or a flue fault | No. Turn it off, ventilate, seek medical advice, and have it tested before any further use |
| A lazy yellow or orange flame where it used to be crisp and blue | Restricted air supply, a dirty burner or incorrect gas pressure | Stop using it and book a service |
| Soot, black marks or staining around the appliance or its outlet | Incomplete combustion, which has been going on for a while | Stop using it and book a service |
| The heater lights, then shuts itself down after a while | Often the oxygen depletion sensor doing exactly its job, or a pilot or thermocouple fault | Do not keep relighting it. Book a service and mention the pattern |
| Glass sooting up on a gas log fire | Combustion or flue performance, sometimes log placement after cleaning | Book a service. Never reposition ceramic logs by guesswork |
| Noticeably less heat than last winter | Dust on the burner and heat exchanger, or a fan losing airflow | Usable, but this is the classic overdue service |
| A rattling or louder fan | A bearing, a build up of dust, or something loose in the cabinet | Usable short term. Worth booking |
If you are in the top four rows of that table, the appliance stays off until somebody licensed has looked at it. There is no version of that judgement we would soften.
What a proper gas heater service involves
A service is not a look and a wipe. This is broadly what a licensed gasfitter should be doing, and what we do.
- A carbon monoxide test on the appliance in operation.
- Gas pressure tested and adjusted to the manufacturer’s specification, which for LPG is not the same figure as natural gas.
- Burner, injectors and pilot assembly cleaned, and the flame pattern assessed against what it should look like.
- The oxygen depletion sensor and pilot shutdown tested, not just observed.
- Heat exchanger inspected for cracking or corrosion.
- On a flued appliance, the flue, seals and terminal checked, including the external terminal where salt air does its work.
- Fan, air inlets and filters cleaned, which is usually where the lost heat output has gone.
- Thermostat, controls and safety shutdowns operated and confirmed.
- Gas connection, hose and regulator checked for leaks.
- A straight account of anything that needs a part, and what happens if it waits.
That last point matters more than the list. A service is worth having because of what it tells you, and a report that says everything is fine is a useful result rather than a wasted visit.
Who is doing the work
Every service is carried out by a licensed gasfitter. Jay, our Head Gasfitter, has seventeen years on the tools and is qualified across plumbing, drainage, gasfitting and roofing, and Jeff is fully licensed in all four. That combination is not just a line on a website. A flue passing through a roof is roofing work. A gas line is gasfitting work. Having both in one van is the difference between one visit and two.
We are also preferred Rinnai contractors, and Coffs Harbour has no reticulated natural gas, so the appliances we service in town run on LPG. Details like correct LPG test pressures and the right injector for the fuel are exactly where an appliance set up for the wrong gas gives itself away.
Before winter, not during it
The best time to book a gas heater service is the end of summer or early autumn, for the same reason it is the best time to book any heating work.
The first cold week of the year is when everybody discovers their heater at the same time, and it is also the week that any appliance needing a part is going to be waiting on one. A service in February or March means a working heater in June, and if something does need replacing there is time to do it without anybody sitting in a cold house.
It is the same logic that applies to wood appliances, where the flue needs sweeping annually and where skipping it has consequences of its own. If you have both, book them together. We are one of very few businesses around here that also sweeps chimneys and flues, so it is one visit rather than two.
What about heaters with no service requirement
Worth saying plainly, because it comes up in the showroom. An electric appliance has no combustion, no flue, no gas connection and no carbon monoxide, and therefore no service interval of this kind. If the servicing obligation is part of what is putting you off gas, that is a legitimate reason to look at whether an electric fireplace would heat your room instead.
It is a genuine trade off rather than a free win. Electric costs more per hour of heat than wood and cannot match a flued gas appliance for output in a large space. But the maintenance column really is close to empty, and for some households that is the deciding factor. Our comparison of a gas fireplace, a wood fireplace and an electric flame fire puts the three side by side.
FAQs
How often should a gas heater be serviced?
At least every two years by a licensed gasfitter, and annually if the house is dusty, you have pets, or the heater works hard through the season. Energy Safe Victoria recommends that all gas heaters are serviced at least every two years by a qualified gasfitter. New South Wales guidance instead directs you to the manufacturer’s specifications, so check your handbook, because if it specifies annual servicing then annual applies to your appliance.
Is it a legal requirement to service a gas heater?
Servicing intervals for domestic appliances are recommendations rather than a legal obligation in New South Wales. Who performs the work is a legal matter. Gas work must be carried out by a licensed gasfitter under the Gas and Electricity (Consumer Safety) Act 2017, as set out in the New South Wales Government’s gas safety guidance, so a service is not something a homeowner or a general handyman may lawfully do. Insurance policies and manufacturer warranties may also require a service history.
Can a gas heater produce carbon monoxide?
Yes, if it is not burning properly. Carbon monoxide has no colour, smell or taste, and the change from clean combustion to poor combustion is gradual and invisible, which is precisely why servicing exists. Warning signs include a lazy yellow flame where it used to be blue, soot or staining around the appliance, and headaches, nausea or tiredness that ease when you go outside. A carbon monoxide test is part of every service we carry out.
What is an oxygen depletion sensor?
An ODS is a safety device built into the pilot assembly of a gas heater. The pilot flame is aimed at a thermocouple that keeps the gas valve open. If oxygen in the room falls, the flame changes shape and moves away from the thermocouple, the signal stops and the gas shuts off. Every unit we sell has one. It is not a carbon monoxide detector, and because it can drift out of alignment or become dirty, its shutdown behaviour should be tested at each service.
Why does my gas heater keep shutting itself off?
Stop relighting it, and book a service. A heater that shuts itself down is usually a safety device working rather than a heater failing, most often the oxygen depletion sensor, which points at ventilation or combustion. It can also be a pilot or thermocouple fault. Either way, relighting it repeatedly is overriding a safety device by persistence. When you book, describe the pattern, because how long it runs before it cuts out is diagnostically useful.
How often should a commercial gas appliance be serviced?
Every six months. The shorter interval is about hours of use rather than the appliance being different in kind. A commercial appliance can do in a month what a domestic heater does in a season, and in a kitchen it does it in air carrying grease and fat. We service commercial gas equipment on a six monthly cycle and attend commercial breakdowns on site within 24 to 48 hours. If the appliance stopping would stop trade, say so when you book.
Do portable gas heaters need servicing?
They benefit from it, and they need more care in use than a flued appliance because everything they produce stays in the room. Portables sold for indoor use in Australia are rated under 25 megajoules per hour, and the manual specifies both a minimum room size and the ventilation required. Follow those, never use one in a bedroom or bathroom or a closed room without fresh air, and have the hose and regulator checked rather than assumed.
What does a gas heater service cost?
It depends on the appliance, whether it is flued or unflued, and whether it turns out to need parts. Give us the make and model over the phone and we will tell you what the service itself involves and what we charge for it before we book anything. If we find something during the service, you get the cost and the consequences of waiting before we proceed rather than after.
Can I service my own gas heater?
No. Gas work in New South Wales is licensed work, and a service involves pressure testing, combustion testing and safety device testing that require both a licence and equipment. What you can do between services is keep the air inlets and the area around the appliance clear of dust and pet hair, keep the surrounds clear of anything combustible, and pay attention to the flame colour.
Book It Before the First Cold Week
If you cannot remember the last time your gas heater was serviced, that is the answer to the interval question. Give us the make and model and we will tell you what the manufacturer specifies for your appliance and get it booked.
Come and see us at 92 Industrial Drive, North Boambee Valley, call (02) 6652 2411, or send us an enquiry. We service gas heating, gas log fires and commercial gas equipment across Coffs Harbour, Scotts Head, Dorrigo, Grafton and everywhere in between, and we have been doing it as the same family business since 1982.
Written by the team at Coffs Gas Company.
Disclaimer: This article is general information only and is current at the time of writing. Recommended service intervals vary between manufacturers, jurisdictions and appliance types, and the manufacturer’s instructions for your appliance take precedence. If you suspect a gas leak or carbon monoxide, turn the appliance off, ventilate the area, seek medical advice where anybody is unwell, and contact a licensed gasfitter before further use.
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