Do Gas Heaters Give Off Carbon Monoxide?

If you have ever asked yourself whether your gas heater could be putting your family at risk, you are not alone. It is one of the most common safety questions Perth homeowners ask each winter, and the answer matters more than most people realise. Understanding the relationship between gas heaters and carbon monoxide is essential for keeping your household safe during the colder months.

The short answer is yes. All gas heaters produce carbon monoxide (CO) as a by-product of combustion. Under normal operating conditions, CO is safely vented outside or diluted to harmless levels. However, when a heater is faulty, poorly maintained, or incorrectly installed, dangerous amounts of carbon monoxide can leak into your living space without you ever knowing it.

What Is Carbon Monoxide and Why Is It Dangerous?

Carbon monoxide is a colourless, odourless, and tasteless gas. It is often called the “silent killer” because you cannot see, smell, or taste it, yet prolonged exposure can be fatal. When inhaled, CO enters your bloodstream and replaces the oxygen your body needs to function. Your organs, brain, and heart are starved of oxygen, which can lead to serious injury or death in high concentrations.

The link between gas heaters and carbon monoxide poisoning is well documented in Australia. The Victorian Department of Health reports that faulty gas heaters have been directly responsible for carbon monoxide-related deaths and hospitalisations, particularly in homes using older or unserviced appliances. While these incidents are preventable, they remain a real threat every winter.

How Do Gas Heaters Produce Carbon Monoxide?

Every gas heater burns natural gas or LPG to generate heat. This combustion process produces several by-products, including water vapour, carbon dioxide, and small amounts of carbon monoxide. In a properly functioning heater, these by-products are expelled safely through a flue or chimney, or in the case of unflued heaters, diluted through adequate room ventilation.

Problems arise when the combustion process is incomplete. This can happen when burners are dirty or damaged, gas pressure is incorrect, the heat exchanger is cracked, or the flue is blocked or disconnected. When combustion is incomplete, the heater produces significantly more CO than it should, and that gas ends up inside your home rather than being safely expelled.

The type of heater you have also affects the level of risk. Understanding the connection between carbon monoxide and gas heaters starts with knowing what type of system is installed in your home.

Flued vs Unflued Gas Heaters

Flued gas heaters use a pipe or chimney to direct combustion by-products, including CO, outside the building. These are generally safer, but open-flued models can still spill carbon monoxide back into the room if indoor air pressure changes, such as when exhaust fans or rangehoods are running at the same time.

Room-sealed (balanced flue) heaters are the safest option. They draw air from outside for combustion and expel all fumes externally through a sealed system. There is virtually no risk of CO entering your living space with these units when they are correctly installed and maintained.

Unflued gas heaters release all combustion by-products directly into the room. These heaters rely entirely on room ventilation to disperse CO and other fumes. If windows and doors are closed, or ventilation is inadequate, carbon monoxide can accumulate to dangerous levels quickly. In Western Australia, restrictions apply to the installation of unflued gas heaters for this reason.

Warning Signs Your Gas Heater May Be Leaking Carbon Monoxide

Because carbon monoxide is impossible to detect with your senses alone, you need to watch for indirect warning signs that your heater may not be operating safely. There are several indicators related to gas heating and safety issues that every homeowner should be aware of.

• A yellow, orange, or sooty flame instead of a clean blue flame
• The pilot light repeatedly goes out or makes popping sounds when igniting
• Soot marks, staining, or discolouration around the heater or on walls and ceilings nearby
• A stale or stuffy smell in the room when the heater is running
• Excessive condensation on windows when the heater is in use

Physical symptoms such as headaches, dizziness, nausea, or fatigue that improve when you leave the house

If you or your family members experience symptoms like headaches, dizziness, nausea, confusion, or unusual tiredness that seem to improve when you leave the house, carbon monoxide exposure could be the cause. These symptoms are often mistaken for the flu or general winter illness, which makes CO particularly dangerous.

If you suspect a carbon monoxide leak, turn off the heater immediately, open all doors and windows, leave the house, and call a licensed gas fitter. Do not use the heater again until it has been professionally inspected and cleared.

How to Protect Your Family from Carbon Monoxide Poisoning

The most effective way to protect your household is through regular professional maintenance. A licensed technician can identify and resolve issues that you would never spot on your own. When you schedule a gas heating service, the technician will inspect the burner, heat exchanger, flue system, and all safety controls to confirm everything is operating correctly.

Schedule Regular Gas Heater Servicing

All gas heaters should be professionally serviced at least every two years, and annually if the unit is more than 10 years old or used heavily through Perth’s winter season. A thorough gas heater service includes cleaning the burner and components, checking gas pressure, inspecting the flue for blockages or disconnections, testing ignition and safety controls, and performing a carbon monoxide spillage test.

If you are in Perth and looking for reliable gas heating service Perth professionals, choosing a locally based, licensed team ensures your heater is checked against current Australian safety standards and WA regulations. A gas heater service Perth appointment typically takes under an hour and can prevent the kind of faults that lead to carbon monoxide leaks.

Install a Carbon Monoxide Alarm

While regular servicing is your first line of defence, a carbon monoxide alarm provides an additional safety layer. Carbon monoxide detection in gas heaters has become increasingly accessible for Australian homeowners, with audible alarms available that meet European (EN50291) or US (UL2034) standards. There is currently no Australian-specific standard for domestic CO alarms, but alarms certified to EU or US standards are widely recommended.

Install CO alarms near every room that has a gas heating appliance and ensure they can be heard from sleeping areas. These alarms detect CO concentrations in the air and alert you before levels become dangerous. They should be tested regularly and replaced according to the manufacturer’s instructions.

Use Your Gas Heater Safely

In addition to servicing and alarms, good everyday habits reduce your risk significantly.

• Keep rooms ventilated when using a gas heater, especially unflued models
• Avoid running exhaust fans, rangehoods, or bathroom extractors at the same time as an open-flued heater, as this can draw CO back into the room
• Never leave a gas heater running overnight or while you are asleep
• Never use outdoor gas appliances indoors, including barbecues and patio heaters
• Keep flammable materials at least one metre away from the heater
• Do not block or cover vents, flues, or air intakes

When Should You Replace Your Gas Heater Instead of Repairing It?

Even with regular servicing, gas heaters do not last forever. Most units have a practical lifespan of around 15 to 20 years, depending on the brand, usage, and maintenance history. If your heater is approaching this age, spare parts may no longer be available, and the cost of repeated repairs may outweigh the benefit.

Older open-flued gas heaters, in particular, pose a higher carbon monoxide risk than modern room-sealed units. If your heater is an older open-flued model, consider replacing it with a room-sealed or balanced-flue heater for significantly improved safety and energy efficiency.

A licensed gas fitter can assess your current heater and give you honest advice on whether a repair or replacement is the smarter long-term investment for your home.

Who Can Service or Repair a Gas Heater in Perth?

In Western Australia, all gas heater repairs, servicing, and installations must be carried out by a licensed gas fitter. This is a legal requirement under WA gas safety regulations. Unlicensed work is not only dangerous but can void your home insurance and leave you personally liable if something goes wrong.

At Joondalup Heating & Cooling, our licensed gas technicians provide professional gas heater and carbon monoxide safety inspections, servicing, repairs, and installations across Perth’s northern suburbs. Every service includes a carbon monoxide spillage test as standard, so you know your heater is safe to use.

We offer same-day response during standard hours, no callout fees, and upfront quotes before any work begins. Whether your heater needs a routine service or you are concerned about a potential CO issue, we are here to help.

Keep Your Family Safe This Winter

Gas heaters are a practical and efficient way to heat your Perth home, but only when they are properly maintained. Carbon monoxide is a real and preventable risk. By scheduling regular servicing, installing a CO alarm, and knowing the warning signs of a faulty heater, you can enjoy a warm home without compromising your family’s safety.

If your gas heater has not been serviced in the past two years, or if you have noticed any of the warning signs listed above, do not wait. Book a service appointment with Joondalup Heating & Cooling today by calling (08) 6200 9718 or requesting a quote online.