All-in-one or split heat pump hot water: which suits your home?

An all-in-one, or integrated, heat pump has the fan, compressor and tank in one unit. Air is drawn across a coil, its heat is moved into the water, and cooled air is pushed back out. Everything sits on one base, with one set of connections.

A split heat pump separates the tank from an outdoor unit that holds the fan and compressor, with pipework joining the two. The tank can sit against a wall or in a more sheltered spot, and the outdoor unit goes where its airflow and noise suit the site. The principle is the same, just spread across two parts.

An integrated unit needs open air around its fan, the clearances from walls and fences that the manufacturer specifies, and room for its chilled exhaust air to get away. Squeezed into a narrow side path, it ends up breathing its own cold air and works harder.

A split frees the tank from those airflow needs. The outdoor unit is smaller and can go on a pad or bracket, as the model allows, where air moves freely. On narrow blocks, such as Yarraville's small Victorian and Edwardian houses, that flexibility can make a heat pump workable where an integrated unit wouldn't sit well.

Every heat pump hums while it runs, a little like an air conditioner's outdoor unit. With an integrated unit, that hum sits wherever the tank sits. If the only spot for the tank is under a bedroom window, yours or the neighbour's, the noise comes with it.

A split lets the tank stay close to the bathroom and kitchen while the outdoor unit goes further away, around a corner or facing the street rather than the house next door. Running the timer through the day helps with either design, because the compressor isn't working while people sleep.

An integrated unit is the simpler job: one base, one set of water connections, one power supply and a condensate drain. With fewer parts there is less to go wrong, and servicing happens in one place.

A split adds pipework between the two parts, which has to be run, insulated and protected, and the electrical supply has to suit both parts as the model requires. More parts mean more connections to check over the years. That is the trade for the freedom to place each part where it works best.

Either way, a licensed plumber connects the water. Our team runs the circuit with safety switch protection, which Energy Safe Victoria's guidance on the Wiring Rules says every final sub-circuit needs, plus any isolator the manufacturer specifies. Hot water services are non-prescribed electrical work, and you receive a Certificate of Electrical Safety.

Both designs work less efficiently as the air cools, and July at Laverton averages a minimum of 5.2 °C. Neither wins outright on cold mornings. The model's cold-weather performance, a backup element and a daytime timer matter more than whether it is split or integrated.

Our view: choose an all-in-one where there is a spot with open airflow that isn't beside a bedroom. Choose a split where the side path is tight, the obvious spot is under a window, or the tank would otherwise end up somewhere the fan can't breathe.