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Can you install a split system on an internal wall?

Yes, you can! Check out our installation examples to find out how.

All the examples are real installations from residential homes to high rise apartments.


Suburb - Mooroolbark, Melbourne 
(residential single storey house)
This installation required running pipes through the roof because the air conditioner was located in a large living room that had cathedral ceilings. The two external walls were not able to facilitate the split system so it was positioned on the wall which backed onto the pitched roof at the back of the house. This allowed the installers easy access to the roof space.
The great thing about installing in this location is it gives you the ability to put the height of the indoor unit at an ideal spot to extract the heat from the high ceilings effectively.
One of the “lucky” things with this install was that the manhole to the roof was right underneath where we needed to access to run the pipes. This made the installation a bit easier and shaved at least an hour off the installation time.

The unit installed was the Mitsubishi SRK71ZMA. It was chosen in this situation because of it’s high powered fan.


Suburb - North Fitzroy, Melbourne 
(Heritage building)

This installation was in an older stlye Heritage listed house. Due to the fact that we were not allowed to locate the outdoor unit on the front of the building or have any external ducting. Our solution was to run the pipes internally through the roof. It involved a small amount of internal duct work to get the pipes into the roof. The outdoor unit was mounted on a roof bracket at the back of the pitched roof out of sight.

Check out the video to see how it was done.

Suburb - Elsternwick, Melbourne 
(older style apartment)

This installation required internal duct work becasue the walls of the lounge room had no external wall. They were butted up against the neighbours apartment whcih was in a long line of apartments. The split system indoor unit had to be in the lounge room so the only way to get the drain outside was using internal ducting. We took the pipes into the bedroom so that they were not visible from the lounge room which made the install just that little bit neater. The pipes went straight up onto the flat tin roof as the apartment was on the top flor of the complex. The drain was then ran down and around the skirting boards to the outer wall. We kept the drain inside the larger duct so that is all looked uniform. The outdoor unit on the roof was in the middle of the apartment and was not visible from any angle from the ground.

Check out the video to see how it was done.

Suburb - Kew, Melbourne 
(older style unit)

Another double brick installation on a wall that adjoins the neighbouring unit. The indoor unit was located in the corner of the room to hide as much as possible the internal duct required to run pipes up into the roof space. The client elected not to install a condensation pump due to the noise factor. The drain was therefore run externally through the kitchen and to a down pipe outside. The outdoor unit is neatly tucked against the back wall and mounted on a wall bracket. 

Internal wall installation  – No plaster cuts

Suburb - Taylors Lakes, Melbourne

This advanced installation required the indoor unit to be installed on an internal wall. The lounge room had floor to ceiling windows on all the external walls leaving no space to mount the air conditioner.

The solution we were able to come up with meant running the pipes up into the roof via the cavity in the wall and running the drain out through not one but two cupboards. Running pipes into the roof and outside is not the issue here. The problem is the drain. The home was sitting on a concrete slab which prevents us from running the drain down under the house (which would also include cutting out plaster). Fortunately the middle of the room backed on to the two cupboards. The unit installed was the Fujitsu ASTG34LFCC 9.2KW. As you can see the outdoor unit on this size air conditioner is bigger than most.


Suburb - Eltham, Melbourne 
(residential house)

The client wanted the unit located on this internal wall because it lined up with another room directly opposite this position. That meant the air conditioner was able to direct airflow into two areas of the house.

The installation required cutting out plaster and taking the pipes and drain underneath the house and then out to the condensor unit located underneath the decking below.

This is a pretty good solution because it not only was the best position for the indoor unit but it kept the outdoor unit completely out of direct sunlight and also out of the weather. This will help with the overall efficiency of the unit (direct sunlight can lower the efficiency of the system) and will minimize wear and tear over the years from the elements.


Suburb - Werribee, Melbourne 
(residential house)

This job is one that we generally don’t find to often. The split system was installed into a bedroom which was located at the front of the house. Normally we would put the indoor unit in the corner of the room so that the pipes and drain would not be seen. The installation would be nice and neat. But the client insisted that the unit sit in the middle of the wall so it would look centered. He also did not want the duct to exit on the other side of the wall near the front door and run around to the outdoor unit or cut out plaster and put the pipes inside the wall.

So, the only solution we had was to install internal duct to cover the pipes and drain. At the end of the day we will always do as the client wishes so long as we know we have given them all their options first. Ironically, he also insisted on the outdoor unit being mounted right outside the bedroom wall and right at the front of the entrance to the house to keep the installation costs down. So on one hand he did not want ducting near the porch but was happy to have ducting and the unit right at the front of the house.

The best solution in our opinion would have been to put the indoor unit in the corner of the room eliminating the need for the internal duct and then run the pipes maybe 3-4 meters to the left of the stairs and mount the unit on the ground. Much neater! But hey…we are here to do what the client wants!

You can read more about installation costs here.


In some installations the indoor unit needs to be positioned on an internal. In this case the customer wanted the unit centered between the bed and the window. The only way to run the pipes outside was to cut out plaster. Generally it will cost around $400-$500 to re-plaster the wall. If your priority is aesthetics over price, then this could be the option for you.

Most people who actually own the property and plan on staying for a while will choose this option.

A 2.5kw Fujitsu split system fully installed in this situation: $2195 including GST, plus $400-$500 to replaster.

apartment 2-1

Suburb – Footscray, Melbourne (apartment building)

This installation is a classic example of how split systems are installed on an internal wall. The client wanted the unit in the middle of the room. To do that we need to cut out plaster and run the pipes, drain and electrical inside the wall. 

Another reason for installing a system this way is due to body corp rules. Many body corps especially in high rise buildings will not allow piping to exit the building higher than the balcony rails. 

Once the installation is finished obviously the wall will require patching and painting so you need to factor that into your budget and also wether that is something you don’t mind doing.

If you do not want to cut plaster out and assuming your body corp allows piping to exit onto the balcony above the rails the easiest and cheapest way to install in an apartment can be found here.

The extra cost to run pipes inside walls runs between $300-$600.