Installing a split system upstairs: pipe runs, drains and outdoor units

An upstairs split has the same parts as any other: an indoor head, an outdoor unit, two refrigerant pipes, a drain and an interconnecting cable, plus a circuit from the switchboard. What changes upstairs is how far the pipes travel and how the drain gets water down to the ground.

The easiest case is a bedroom with an external wall. The head goes high on that wall, the pipes go straight through, and the outdoor unit sits below on the ground or on a bracket behind. Short, direct runs are neater and leave less to go wrong.

If the head has to go on an internal wall, because the outside wall is all window or wardrobe, the pipes usually travel up into the roof space, across and down the outside of the house. That works, but it means more pipework, more cover duct outside and a drain route that needs thought.

Every split system has a maximum pipe length and a maximum height difference between the indoor and outdoor units, and some have a minimum length too. The figures are in each model's installation manual. A long run may also need extra refrigerant, which only a refrigerant handling licence holder can add.

In a double-storey home in Point Cook or Tarneit, a rear bedroom is often a straightforward drop to the yard. A front bedroom over the garage, or one in the middle of the house, may need the pipes taken through the roof space to a side or rear wall. Ask the installer to show you the route on the house, not just the unit positions.

Outside, the pipes run down the wall in a cover duct that can be painted to match. On a street-facing wall, ask about a less visible route.

In cooling mode the indoor head pulls moisture from the air, and that water has to go somewhere. The drain works by gravity, so it needs a steady fall all the way from the head to its outlet. Upstairs, that usually means running it down the outside wall with the pipes to a suitable point at ground level.

Where the head sits on an internal wall and the drain can't fall, a small condensate pump lifts the water instead. Pumps work, but they make some noise, need occasional cleaning and can fail. In a bedroom, a route with natural fall is worth a longer pipe run if the manual allows it. Also ask where the drain ends: water dripping onto a path or a lower roof every summer evening leaves stains.

A ground-level outdoor unit on a pad is the easiest to install and to service for its whole life. The trade-off is a longer vertical pipe run up the wall. It also keeps compressor noise and vibration away from the bedroom it serves.

A wall bracket under the eaves keeps the pipe run short, but every future service then needs safe access at height, which can mean ladder work or scaffolding. Brackets need a solid wall, and on lightweight cladding they can carry vibration into the room behind. A unit on a single-storey section, such as a garage roof, is another option where it's safe to reach.

Wherever it goes, the unit needs clearance for airflow, room for someone to work on it, and a lockable isolating switch next to it but not on it. A spot that saves a metre of pipe but makes every service awkward isn't a saving.

Each split needs a circuit from the switchboard, and an upstairs room can mean a long cable route through the roof space. If the manufacturer calls for a dedicated circuit or a safety switch, Energy Safe Victoria guidance says that must be followed, so we check the board has room before booking.

On the day, expect work in the bedroom, in the roof space if the route passes through it, and at height outside. Clear the wall under the head and the outdoor unit spot, and tell us about pets and side gates. In Victoria, refrigerated air conditioning is a class of plumbing work, installing a split needs a refrigerant handling licence, and the electrical side ends with a Certificate of Electrical Safety.