Replacing gas storage or instantaneous hot water with a heat pump

A heat pump replacement needs stored-water capacity and a suitable place for its equipment. Replacing an existing gas tank can present different site work from replacing a small wall-mounted instantaneous heater.

Assess the new installation on its own requirements. Neither an existing concrete pad nor a nearby power point proves that the location is ready for the selected heat pump.

Start with the old heater type and the household demand

Gas storage heaters keep a tank of hot water available, while instantaneous heaters heat water as it is drawn. A domestic heat pump usually stores heated water in a tank.

Government hot water guidance.

Record shower timing, baths, visitors and any unusually high-use period. The new tank and recovery schedule must meet those needs, particularly when several people use hot water close together.

For an illustrative household accustomed to an instantaneous gas unit, four consecutive showers become an important sizing discussion. Simply selecting the smallest tank that fits the side path is not enough.

Our heat pump assessment considers demand and site layout together. A former gas storage tank’s litre figure is also not a complete specification for the replacement’s recovery and controls.

Check the tank location, base and access

An existing tank site may be useful, but the new unit can have different dimensions, weight, clearances and service access. Ask the installer to confirm the base and placement against its instructions.

Where the old heater is wall-mounted, allow for a new tank footprint and a practical delivery route. Include gates, steps, narrow passages and future access for maintenance or replacement.

Solar Victoria explains that integrated systems combine the heat pump mechanism and tank, while split layouts separate components and can offer different location options.

Solar Victoria planning guidance.

Consider nearby bedrooms, neighbours and other equipment such as air conditioning. The selected location must allow the model’s airflow and noise requirements to be addressed, not just accommodate its outline.

Specify plumbing, electrical work and drainage

Ask the quote to identify new or altered pipework, insulation, required valves and a suitable drainage arrangement. Condensate and relief-valve discharge need the installer’s planned treatment, not an improvised bucket or blocked outlet.

A gas heater’s electrical connection, if present, may only have served controls or ignition. An electrician must assess the circuit and supply required by the selected heat pump, including any electrical element.

The electrical capacity guide distinguishes a new appliance circuit from the home’s wider supply requirements.

Use appropriately qualified trades for water connections, electrical work and safe gas decommissioning. The BPC explains why these responsibilities can involve different licensing scopes.

BPC heat pump installation scopes.

Do not disconnect gas, alter wiring or change safety valves yourself to prepare the site.

Plan the changeover and the final gas decision

Agree when the old heater is removed, the expected interruption to hot water and how the first heating cycle will be handled. Ask about the contingency if further work prevents completion that day.

Include disposal and making good around the old location. For a moved system, confirm what happens to redundant pipework and any wall openings or mounting points.

If incentives are included, follow their approval process. Solar Victoria’s ordinary hot water rebate pathway requires eligibility confirmation before installation, with a separate conditional emergency process.

Hot water rebate requirements.

Replacing the water heater does not end gas supply charges while a gas connection and other gas appliances remain. Review the final account and connection exit as a separate step when the last gas appliance is gone.

Do not move a working heater prematurely solely to match a promotional layout. Choose the timing and location from a complete assessed scope, household need and available budget.

Bring photos of the existing heater and proposed location when you request a replacement quote. The result should make the tank, services, drainage and removal work clear before installation day.