Replacing ducted gas heating with reverse-cycle air conditioning is a chance to rethink how the house is heated, cooled and controlled. It is also more than an appliance swap. The old duct network, electrical supply, indoor unit location and gas connection each need a separate decision. A conversion works best when those decisions are resolved before the existing heater is removed.
Begin with a professional assessment of the home and a room-by-room comfort brief. Decide whether the replacement will remain ducted, which areas it must serve and what other renovation work will change the building’s heating demand. The aim is a complete installation that suits your Australian home, with clear responsibilities for removal, new services and commissioning.
Describe the job the new system must do
Record how the existing heating is used on an ordinary winter day. Note rooms that remain cold, areas that overheat and bedrooms that are usually closed. Include the times people are at home. A household working from one study all day has a different pattern from one using several living spaces simultaneously.
Add summer requirements to the brief. A gas heating network may have been designed only for winter comfort. Introducing cooling means assessing rooms that were previously unimportant to the heating layout, such as a west-facing bedroom or an upstairs workspace. Do not assume every old outlet is ideally placed for the new purpose.
Your Home, the Australian Government’s housing guide, describes reverse-cycle air conditioning as a heat-pump system that moves heat between indoors and outdoors. It can provide both heating and cooling. Its suitability still depends on equipment selection and installation, so ask the designer to explain the proposed model against your actual rooms and climate.
For more detail on this part of the project, see Replacing Evaporative Cooling with Reverse-Cycle Air Conditioning.
Put the conversion into the wider sustainable renovation plan. If an extension, glazing replacement or layout change is imminent, give the installer the proposed drawings. Designing only for today’s arrangement can leave the new equipment poorly matched to the finished home.
Improve the building before final sizing
Identify comfort problems that do not begin with the heater. Missing insulation, draughts and unshaded glazing can increase the work demanded of any replacement system. Have planned improvements included in the heating and cooling assessment so the equipment is selected for the intended building condition.
If the ceiling insulation is being reviewed, coordinate the insulation upgrade with access to the indoor unit and ducts. Ask who protects and reinstates insulation disturbed by the installation. An efficient appliance should not arrive with an unpriced patch of displaced insulation left behind it.
Similarly, discuss draught proofing alongside ventilation needs and any remaining combustion appliances. The responsible professional should identify openings that serve a necessary purpose. Sealing every visible grille is not an appropriate homeowner strategy simply because the gas heater is being replaced.
Ask the installer for the basis of the capacity selection. Floor area alone does not describe ceiling height, window exposure, construction or how rooms connect. Request heating performance information relevant to local winter conditions as well as cooling capacity. The old heater’s label should not be the sole sizing reference.
Audit the existing ducts without assuming reuse
Condition and access
Have the contractor inspect the accessible ductwork, connections, insulation and supports. The assessment should identify damage, contamination concerns, restricted routes and sections that cannot be inspected without further access. A statement that ducts appear present is not evidence that they are suitable for the proposed system.
Your Home notes that duct leakage and inadequate insulation can cause energy loss and condensation risks. For a conversion, ask how the existing network will be assessed against the new equipment’s requirements. Retaining serviceable components may be possible, but compatibility should be confirmed in writing by the responsible installer.
Airflow, outlets and return paths
The new design needs suitable supply and return air arrangements. Your Home highlights the importance of a return path from rooms served by duct outlets. Ask how the system will work when bedroom doors are in their normal position. A large central return grille does not explain how air gets back from every occupied room.
Have outlet locations reviewed for the new heating and cooling brief. Existing floor grilles, ceiling diffusers or duct branches may be retained, altered or abandoned depending on the design. The quotation should show which outcome applies at each location, including the repair of openings that will no longer be used.
Ask for a retained-and-replaced schedule
A simple drawing can identify the old heater, indoor unit, outdoor unit, retained ducts, new ducts and outlet changes. Add notes about inspections and performance checks. This schedule makes a proposal to reuse ductwork reviewable and prevents a vague allowance from becoming an assumption that every existing component must remain.
Decide whether to keep a ducted arrangement
A ducted replacement may suit a household that regularly conditions several rooms and prefers discreet outlets. However, the presence of old ducts does not require you to reproduce the same arrangement. If only a few rooms need regular heating, ask whether a different reverse-cycle configuration better matches the usage pattern.
Keep this comparison focused on the conversion’s practical consequences. How many areas will be served? Which old openings need repair? Where will new equipment be placed? What disruption is involved? A lower equipment price is less helpful if the alternative leaves important rooms uncomfortable or requires extensive unpriced building work.
For a ducted proposal, describe the zones you expect to use together. Ask which zones can operate separately, what restrictions apply and where temperature is sensed. A zone button is not proof that each room has independent temperature control. Have the installer demonstrate the intended controls before the final selection is approved.
Assess electrical capacity before ordering
Give a licensed electrician the exact proposed equipment documentation. Ask for an assessment of the circuit requirements, switchboard condition and household demand. Include other planned electrical upgrades, such as induction cooking or a heat-pump water heater, so the work can be coordinated.
Energy Safe Victoria’s household wiring guidance advises professional attention to ageing wiring and explains that safety switches and circuit breakers perform different functions. For this renovation, the important decision is to obtain an installation-specific electrical scope. A switchboard that looks tidy does not establish that the proposed additional load is suitable.
Request separate prices for the appliance connection and any broader electrical work. Confirm the cable route, access needs, making good and relevant completion documentation. If a supply upgrade is required, establish the process and timing before arranging removal of the existing heating.
Do not assume a particular system size universally requires single-phase or three-phase power. The selected product and the home’s supply determine what must be assessed. Equipment substitutions should return to the electrician for confirmation rather than proceeding because the replacement is described as equivalent.
Plan equipment locations and drainage
Have the indoor unit location shown with the space needed for servicing and eventual replacement. Ask how filters and service panels will be reached after cabinetry, insulation and other work are complete. A unit fitted into a difficult cavity may be technically possible but inconvenient to maintain.
For the outdoor unit, review access, airflow, nearby windows and the effect on neighbours. Have the installer check applicable noise and placement requirements for the property. Avoid enclosing the unit inside a decorative screen until the manufacturer-supported clearances and service needs are understood.
Ask where condensate will discharge and who provides the drainage connection. Include any visible pipework and penetrations in the drawings so they can be coordinated with the house exterior. Do not accept an undefined arrangement that could leave water across a path or against building fabric.
In strata property, establish whether equipment, penetrations or services affect common property. Obtain the relevant permissions before ordering an installation that relies on those changes. For any home, confirm the approval pathway for the actual work instead of assuming that replacement equipment is automatically exempt.
Separate appliance removal from closing the gas account
Have an appropriately licensed gasfitter handle disconnection and any required capping or alteration of the old appliance’s gas supply. The removal scope should also address the heater, flue where relevant, redundant controls and the repair of disturbed surfaces. Homeowners should not disconnect gas components or investigate pipework themselves.
List every remaining gas appliance before deciding what happens to the property connection. A gas cooktop or water heater may still need supply after space heating changes. Removing one heater does not, by itself, remove all gas charges from the household bill.
Your Home distinguishes gas disconnection from permanent removal of the connection and advises arranging network work through the gas retailer and distributor. Ask your retailer for the current options, charges and process for your property. Confirm what happens to ongoing supply charges and keep the written response with the project records.
If old equipment or surrounding materials raise asbestos concerns, arrange appropriate asbestos assessment before disturbance. The removal contractor should identify the accessible scope and any further investigation needed. Do not treat appliance disposal as permission to damage uncertain insulation or building products.
Allow for the complete installed cost in AUD
This hypothetical budget illustrates a ducted conversion with an assessed house, a new matched reverse-cycle system and defined duct alterations. All amounts are in AUD and include assumed GST. These are planning inputs, not current Australian market prices or a quotation for a particular brand.
- Equipment package and specified controls: AUD $8,000.
- Mechanical installation and duct alterations: AUD $4,000.
- Electrical connection and limited associated work: AUD $1,800.
- Gasfitter disconnection and old heater removal: AUD $900.
- Repairs to redundant openings and disturbed finishes: AUD $1,100.
- Specified access and disposal allowance: AUD $700.
The illustrative base total is AUD $16,500. A separate AUD $2,000 reserve gives available project funds of AUD $18,500. Major switchboard or network upgrades, hazardous-material work, extensive ceiling reconstruction, approval fees and gas-network abolishment are excluded. If relevant, they need actual prices rather than an assumption that the reserve covers them.
Keep the gross installation cost visible if an incentive may be available. Ask the relevant programme administrator or approved provider to confirm current eligibility, equipment conditions and the point at which approval is required. Do not deduct an unconfirmed rebate when deciding whether the project fits your renovation budget.
Compare running costs using equal comfort assumptions
A useful comparison starts with what each system is expected to heat and for how long. Do not compare last year’s limited gas use with a forecast that assumes the new system heats every room all day and cools the house through summer. Separate the cost of providing the old service from the cost of any additional comfort you plan to use.
For a straightforward arithmetic example, suppose an installer estimates 12 kWh of electricity for an explicitly defined day of operation. At an assumed GST-inclusive tariff of AUD $0.35 per kWh, that day costs AUD $4.20. This is not a performance prediction: both energy use and tariff are hypothetical, and a nameplate power rating multiplied by operating hours may not represent actual consumption.
Compare that estimate with a gas-use assessment for equivalent conditions, using the units and charges on your bill. Keep supply charges separate from consumption. Ask what assumptions were made about weather, thermostat settings, system condition and occupied rooms, then test the estimate against actual bills after installation.
If you have solar, consider when heating is needed relative to generation and household demand. Do not assume every kilowatt-hour used by the new system comes from surplus solar. The value of self-consumption also depends on the electricity plan and what otherwise would have happened to that energy.
Make commissioning part of completion
When comparing installation quotes, include the model combination, duct schedule, electrical work, gas removal, drainage and making good. Ask who is responsible for commissioning and what records will be supplied. A proposal that simply promises heating and cooling leaves too much of the conversion undefined.
At handover, have the installer demonstrate heating, cooling, zone controls, filters and the normal shutdown procedure. Check the rooms in their intended operating arrangement, including the usual door positions. Ask how unresolved comfort differences will be investigated and who to contact if water, unusual noise or an operational fault appears.
Keep the manuals, trade documentation, gas-account correspondence and photographs of concealed work together. A successful conversion leaves more than a working outdoor unit: the house has a suitable heating and cooling plan, the old gas installation has been properly addressed, and the household understands how to use and maintain the replacement.