Installing split systems on internal brick walls in apartments

Yes, it is possible to install a split system on a wall that does not back onto the outside of the building! Each situation can be very different and we can assess individual apartments to see the best way to go about it. 


Generally internal duct work will be required.

Installation examples

Internal brick cavity

Suburb – Footscray, Melbourne (second floor apartment – double brick)

This installation was a replacement of an old unit.

The unit was located on an internal brick wall which fortunately had a small cavity running behind it which had the existing pipe work inside it.

This allowed us to pull out the old pipes and replace them with new pipes for the replacement  air conditioner.

Installing new pipes covers your 6 year installation warranty.

Getting the pipes in is not as easy as it may seem but having experience with running pipes in difficult situations allowed us to get them in.

The old outdoor unit had to be taken down off the wall bracket and the new one put in it’s place. Working off a scaffold was the simplest way of doing this.

Unit installed was the 5kw SAMSUNG WIFI model.


Internal brick wall 1

Suburb – Collingwood, Melbourne (third floor apartment – double brick)

This installation required mounting the unit on an internal wall. Being single brick on the internal wall (no cavity) meant that the only option was to run the pipes internally on the wall and up onto the roof space where the outdoor unit was mounted on the flat roof above. The client preferred to have the internal ductwork to be in the bedroom as opposed to the bathroom on the other side of the door.

Being on the third and top floor of the apartment meant we where able to mount the outdoor unit on the flat roof above. The drain was run out through the bathroom and down the back of the apartment building. Body corporate approval was needed to run the drain on the outside of the building.

A 3.5kw Samsung split system fully installed in this situation: $2430 including GST



Internal wall brick 2

Suburb – Elsternwick, (2nd floor apartment – double brick and flat roof)

The installation here in Elsternwick was one that had to have internal duct work. The apartment was stuck in the middle of two other apartments which left only the front and back of the premises available to run pipes and drain. The indoor unit had to be located in the lounge room not the bedroom. Our solution was to put it on an internal wall and run the pipes and drain into the adjoining bedrrom wall instead of running them in the lounge room. The client prefered that option.

The duct in the corner of the bedroom blends in fairly well and is also able to be painted to match the wall. The pipes ran up onto the flat roof above which is where the outdoor unit was located. The drain ran down and across behind the bed to the outside wall where the drain was able to be put into the down pipe.

A 4.2 Mitsubishi Electric split system fully installed in this situation: $3225 including GST



Internal duct work on wall

 Suburb – South Bank, (no room for pipes inside cavity wall) 

This installation is the worst case scenario for installing in apartments. The only option we had for getting the pipes and drain outside was to run them internally and cover them with plastic duct. One unit is in the lounge room and one is in the bedroom.   

  • The walls where solid concrete with no cavity between the plaster (can’t cut plaster and put pipes in walls)
  • The indoor units had to have internal ductwork.
  • The body corporate wouldn’t allow any external duct work.    (gaining body corporate approval)


Lounge room unit is the Fujitsu ASTG24LFCB and the bedroom unit is the Fujitsu ASTG09KMCA









The switchboard was on an internal wall on the other side of the room from the outdoor unit. (outdoor unit requires power). The electrical supply was run around the edges of the room inside a small plastic duct. Fortunatly in this situation, most of the furniture in the room sat against the walls anyway so once they where back in place the duct was not visible. If you choose to paint over it, it is almost unrecognisable as it blends in with the skirting.

room layout electrical southbank