Ducted vs Wall Gas Heater: Key Differences Every Melbourne Homeowner Should Know

Updated May 2026 — Around The Clock Plumbing Pty Ltd, Oakleigh South.

Ducted and wall gas heaters serve the same basic purpose — heating your home — but they work differently, suit different homes, and have different servicing, repair and replacement considerations. If you're deciding between heater types, or trying to understand what you already have, this guide explains the key differences and what each means in practice.

How Ducted Gas Heating Works

A ducted gas heating system has a central furnace unit — typically in a roof space, under-floor void or utility cupboard — that burns gas to heat air, then distributes that warm air through a network of ducts to outlets in each room. The system is controlled by a central thermostat and, in zoned systems, individual zone controllers that let you heat selected rooms independently.

Ducted systems are well suited to larger homes where whole-home or multi-zone heating is needed. They're the most common gas heating type across Melbourne's family homes built from the 1970s onward. The main ongoing requirement is annual servicing — and because the furnace unit is often in a roof space or concealed location, the heat exchanger condition is particularly important to check, since visual inspection alone won't reveal cracks.

How Wall Gas Heaters Work

A wall gas heater — sometimes called a wall furnace or space heater — is a self-contained unit mounted on or recessed into a wall, heating the room it's in directly. Older models use a standing pilot light and manual controls; more recent units have electronic ignition and thermostats. They don't use ducts, so they're simpler to install and suited to heating individual rooms or smaller homes.

Wall heaters are common in Melbourne's older housing stock — particularly in units, townhouses and period homes where ducted systems were never installed. Many are significantly aged. An older wall furnace that hasn't been serviced in several years is a higher CO risk than a well-maintained ducted system, because the heat exchanger in a wall unit is smaller and more susceptible to cracking from thermal cycling.

Key Differences: Ducted vs Wall Gas Heater

• Coverage — Ducted systems heat multiple rooms simultaneously via outlets. Wall heaters heat one room or open-plan space directly.

• Installation — Ducted systems require ductwork and a concealed furnace. Wall heaters require only a gas connection and a flue through the wall.

• Running cost — Both burn gas, but ducted systems heating a whole home will cost more to run than a wall heater used for spot heating. Zoning reduces this significantly in ducted systems.

• Servicing — Both require annual servicing by a licensed Type A gas fitter, including a heat exchanger integrity test. The test method differs between types but the requirement is the same.

• Repair vs replace threshold — Ducted systems have a longer serviceable life (15–20+ years with proper maintenance). Older wall furnaces over 15 years old with any faults are generally better replaced than repaired, given parts availability and safety considerations.

Which Type Is Right for Your Home?

If you're in a larger home and want whole-home heating with zone control, ducted gas is the practical choice — provided you have the roof space or under-floor void for the installation. If you're in a smaller home, unit or apartment and want to heat one or two rooms efficiently without major installation work, a modern wall heater or a reverse-cycle split system are both reasonable options. We give honest advice rather than defaulting to the more expensive recommendation.

Fast arrival → accurate diagnosis → permanent fix applies here too: if you call us about a heater problem, we'll assess what you have, tell you honestly whether it's worth repairing, and give you a fixed-price quote before any work starts.

Common Questions: Ducted vs Wall Gas Heater

Can I convert from a wall heater to ducted gas heating?

Yes, in most homes. It requires installing a central furnace unit, running ductwork through the roof space or under-floor, and fitting outlets in each room. It's a significant installation job but gives you whole-home heating from a single unit. We can assess your home's suitability and provide a fixed-price quote.

How often should a ducted gas heater be serviced?

Annually for residential use. Every two years is the legal minimum for rental properties. Annual servicing catches heat exchanger faults and combustion issues before they become safety problems.

My wall heater is 20 years old — should I repair or replace?

At 20 years, replacement is usually the better call — particularly if the unit hasn't been serviced regularly. Parts availability declines for older units, and the heat exchanger in an aged wall furnace is a legitimate safety concern. We'll inspect it and give you an honest assessment.

Do both ducted and wall heaters need a heat exchanger test?

Yes — both types have a heat exchanger and both require an integrity test as part of a proper service. The test method differs between types but the safety requirement is identical.

Written and reviewed by Christopher Unwin — founder, Around The Clock Plumbing Pty Ltd, Oakleigh South. BPC Licence #50694, Type A gas, 22 years' experience. National Council member, Master Plumbers Australia & New Zealand.