Are old gas space heaters still safe to use?

Gas space heaters come in a few types. Room-sealed heaters take combustion air from outside and send the products back out through a sealed flue. Open-flued heaters take the air they burn from the room and rely on a flue and natural draught to carry the products away. Many older wall furnaces and inbuilt heaters in Melbourne homes are open-flued.

Energy Safe Victoria says open-flued gas heaters can spill carbon monoxide more easily than other types, which makes them more dangerous. If the flue is blocked, the heater is poorly maintained or the room is under negative pressure, combustion products can come back into the room. Its 'Be Sure' campaign warns that all gas heaters can spill carbon monoxide, a gas you can't see or smell.

Victoria's Department of Health lists possible symptoms of carbon monoxide exposure including tiredness, headaches, dizziness, nausea, shortness of breath and confusion. If people feel unwell when the heater is on and better away from it, turn it off, get everyone into fresh air and get medical advice.

From 1 August 2022, Energy Safe Victoria banned the sale of old, unsafe open-flued gas space heaters, meaning those without safety shutdown features. The ban includes second-hand heaters. If you're not sure whether your heater has safety shutdown features, a gasfitter can tell you at the next service.

If you're buying a house or moving into one with an older wall heater, find out its service history. A heater nobody has serviced for years should be checked before the first cold night. In rentals, providers who entered a new agreement after 29 March 2021 must have a licensed or registered gasfitter carry out a gas safety check every two years.

Energy Safe Victoria recommends that all gas heaters be serviced at least every two years by a qualified gasfitter, including testing for carbon monoxide leakage. It says a service should include a visual inspection of the appliance and flue, a negative pressure and combustion spillage test, internal cleaning, repair or replacement of parts, and running the appliance to confirm it works safely.

Gas heater servicing is done by a gasfitter licensed for Type A appliance servicing, not by an electrician. Ask the gasfitter to explain the results, including how the negative pressure test was done with exhaust fans and the rangehood running, and keep the report with the heater's details. Energy Safe Victoria says a carbon monoxide alarm helps but should never replace regular servicing.

Energy Safe Victoria advises watching for changes in how a gas heater runs, such as a change in flame colour. If anything changes, a qualified gasfitter should inspect it and check for carbon monoxide leakage, and Energy Safe Victoria suggests considering replacement if a heater is old or hasn't been serviced for several years. Until it's checked, leave it off.

Changes to the house matter too. Energy Safe Victoria advises against running kitchen rangehoods or bathroom exhaust fans while a gas heater is on, because the negative pressure can draw carbon monoxide into living spaces. It also warns that renovating or draught-sealing a home with an open-flued heater may change the ventilation the heater needs.

If the heater is old, unserviced, has failed a service or needs major parts, replacing it is often the better call. A reverse-cycle air conditioner is a heat pump: it moves heat from the outside air into the room, delivering three to five units of heat for each unit of electricity, with no flue and no combustion inside the house. It cools in summer as well.

Switching involves more than one appliance swap. A licensed gasfitter disconnects and caps the old heater, the split system is sized for the room, and an electrician runs a circuit from the switchboard with a lockable isolator beside the outdoor unit. Owner-occupiers aren't required to switch gas space heating to electric, but in rentals, from 1 March 2027 a heater that breaks and can't be repaired must be replaced with an efficient electric reverse-cycle air conditioner in the main living area.