Why does my heater smell when I turn it on for the first time in winter?

Heater smells on first use in winter: normal or not?

The short answer

A dusty, slightly burnt smell on the first run of the season is usually dust burning off the heat exchanger, coil or element, and it fades. Switch the heater off if the smell is sharp or fishy like hot plastic, comes from a power point or plug, keeps getting stronger, or smells like gas. Those need checking before the heater runs again.

The normal first-run smell

Over summer, dust settles inside heaters and ducts. Gas ducted heaters, reverse-cycle units, panel heaters and oil column heaters all burn some of it off the first time they get hot. Expect a dusty, toasty smell that fades over the first run or two. Cleaning the filters and the return air grille before the first cold night cuts it right down.

A reverse-cycle unit can also smell musty when it first switches to heat. That usually means dust and moisture on the indoor coil and fan. It isn't dangerous in itself, but a smell that lingers week after week means the unit is due for a clean.

Smells that mean switch it off

A sharp chemical or fishy smell, like hot plastic, often comes from overheating wiring, a plug, a power point or a part inside the heater. Switch the heater off and leave it off until it's checked. If the smell is coming from a power point or the switchboard, switch off at the switchboard if it's safe to reach. If there is smoke, fire or immediate danger, get everyone out.

A rotten egg smell near a gas heater suggests gas. Turn the heater off if it's safe to, open doors and windows, don't use switches near the smell, and contact your gas distributor using the faults details on your gas bill.

Carbon monoxide has no smell

With gas heating, a smell isn't the warning to rely on. Energy Safe Victoria warns that all gas heaters can spill carbon monoxide, which you can't see or smell, and recommends servicing gas heaters at least every two years by a qualified gasfitter, including a carbon monoxide test. If anyone gets headaches, dizziness or nausea while the heater runs, turn it off, get into fresh air and seek medical help.

Our licensed electricians check power points, plugs, circuits and the electrical side of reverse-cycle and ducted systems. Burners, flues and gas valves are work for a licensed Type A gasfitter.

What you can safely do now

Clean reverse-cycle filters and vacuum the return air grille before the first cold night.
Open a window for the first run so the dust smell clears faster.
Keep curtains, bedding and stored boxes well clear of heaters and outlets.
If a smell is sharp, fishy or electrical, switch the heater off and leave it off until it's checked.

Services that can help

Heater Not WorkingGas ducted or reverse-cycle heating that won't start or heat.Gas Ducted Heater ServicingArrange gas heater maintenance with the correct licensed trade.Heating & Cooling ServicingPreventative servicing for split, ducted, evaporative and gas systems.

Sources for this answer

3 sources, with the date each was checked

1.Energy Safe Victoria: All gas heaters can spill carbon monoxide (CO) – a gas you can’t see or smell that can make you seriously unwell or kill you. Accessed 30 September 2026.
2.Energy Safe Victoria: To avoid the risk, we recommend that all gas heaters are serviced at least every two years by a qualified gasfitter. A qualified gasfitter will inspect your heater and check its installation, including testing for CO… Accessed 30 September 2026.
3.Department of Health (Victoria): When carbon monoxide is inhaled, it replaces oxygen in the blood, which may cause symptoms including tiredness, shortness of breath, headaches, dizziness, nausea, weakness, confusion or chest pain. Accessed 30 September 2026.

General information for homes in Victoria. Every installation is different, so treat this as a starting point. Where this answer refers to Victorian safety or rental rules, the sources above have the current requirements.