How does a box unit work?
The front half blows cooled air into the room. The back half, poking outside, gets rid of the heat. The compressor lives in the same box, in the wall, rather than in a separate outdoor unit.
Some models only cool, so check before you count on one for winter. Several brands still sell them: Midea, Gree, TECO, LG and Bonaire all list window or window-wall units in their Australian ranges. We don't sell any of them.
Where a box unit still makes sense
The strongest case is replacing an old one. If there's already an opening in the wall, a new box that fits it can be a straightforward swap.
They can also suit a room where an outdoor unit has nowhere to go, or a bungalow or granny flat that needs simple cooling.
If you're starting from scratch, a small split is usually the better result. You're not cutting a large hole in the wall, and the noisy part lives outside.
Box unit or wall-hung split?
| Window or wall unit | Wall-hung split | |
|---|---|---|
| Parts | One self-contained box | An indoor unit and an outdoor unit, joined by pipes |
| Opening in the wall | Big enough for the whole box | A small hole for pipes, cable and drain |
| Noise in the room | The compressor is in the box, so you hear more of it | The compressor is outside |
| Heating | Check the model, as some only cool | Reverse cycle models heat and cool |
| Warranty, using Midea as an example | 5 years for window units in residential use | 7 years for split systems in residential use |
Keeping one running well
Westinghouse's support advice for window-wall units makes a good routine for any brand. Clean the filter at least every 2 weeks, keep curtains, blinds and furniture away from the front, and give the room time to cool after you switch on.
If ice forms, Westinghouse says it blocks the airflow and stops the unit cooling. Run the fan on medium or high until it melts. If it keeps happening, disconnect the power and contact an authorised service centre.
The hot side faces outside, often next to a path or a neighbour's window. In Victoria, an air conditioner used for cooling mustn't be heard in a neighbour's habitable room after 11pm, or before 7am on weekdays and 9am on weekends and public holidays. Our noise guide has the other states.
Before you buy a box unit
- Will it fit the existing opening exactly, or does the wall need altering?
- Does it heat, or only cool?
- What's outside where the hot air will blow?
- What power supply does the manual call for?
- In an apartment, does the owners corporation need to approve it?
Do it yourself, or call someone?
You can
- Clean the filter every couple of weeks, as Westinghouse suggests.
- Keep the front clear of curtains and furniture.
- Thaw an iced-up unit by running the fan, and book a service if it keeps icing.
- Check the seal around the box for gaps and draughts.
Leave to a licensed installer
- Cutting or altering a wall opening, which is a builder's job.
- A new power circuit, which needs a licensed electrician.
- Anything inside the sealed refrigerant circuit, which needs an ARC licence.
- Taking away an old unit so its refrigerant is recovered properly.
What we'd do
What we'd do
If a box unit has died in an existing wall opening, a like-for-like replacement is often the simplest fix, as long as the new one fits the hole. If there's no opening yet, we'd look at a small split instead: it's quieter in the room, a reverse cycle model heats as well, and the wall stays mostly intact. A split specialist can tell you quickly whether there's a good spot for the outdoor unit.
