How a high-wall unit heats the room
It's one half of a split system. Consumer NZ describes the outdoor unit as joined to the indoor one by copper refrigerant pipes and wiring, and says split systems work best in the main living area of an open-plan home.
From up near the ceiling, the unit sends warm air out across the room. Consumer NZ says high-wall units circulate enough air to heat a room evenly. Where the unit points matters as much as where it hangs.
Most are inverter models now. BRANZ says inverters are the more common install because they're approximately 30% more efficient than fixed speed systems.
The wall decides how well it works
In one BRANZ survey, more than one household in five said their heat pump wasn't in the best place, which BRANZ called a very poor outcome. Placement is the part of the job most worth questioning.
Avoid corners. BRANZ says a unit in a corner may only partly heat the room, and a draughty spot can affect how it performs. It also warns that a unit mounted too close to the ceiling can short cycle and shut down too early.
Think about where people sit. Consumer NZ suggests aiming the airflow at as much of the room as possible, but not right beside the couch, so nobody ends up with fan noise and a draught in their ear.
Keep it high. BRANZ says units designed for high on a wall shouldn't be used close to floor level, and Mitsubishi Electric NZ won't cover 'Low Wall' installations of its high wall units under warranty. If you want a unit down low, that's a job for a floor console.
High-wall, floor console or ceiling cassette?
| High-wall | Floor console | Ceiling cassette | |
|---|---|---|---|
| Where it sits | Near the ceiling, on a wall | On or just above the floor, against a wall | Fitted into, or hung from, the ceiling |
| Reaching the filters | Hard for some people, especially older people | Easy: Consumer NZ calls it a breeze | Overhead, the same as a high-wall |
| What it needs | A clear stretch of wall up high | Open floor in front, with no furniture in the way | Room in or under the ceiling, and access above it |
| Most likely to suit | One main living area | Rooms without a good high spot | Rooms where wall space is scarce |
Size first, brand second
Heating capacity, in kilowatts, is the number that matters. Read it off the Zoned Energy Rating Label: the main heating figure is measured at 7 degrees outside, and there's a second one at 2 degrees. Where winter nights reach 2 degrees or below, EECA's advice is to make sure the colder figure is at least as high as the 7 degree one.
Get it wrong and you'll notice. BRANZ says an oversized unit keeps switching on and off, while an undersized one runs flat out and defrosts often. Our size calculator gives a rough figure, and the sizing guide explains what an installer adds to it.
Questions for the installer
- Where exactly will the indoor unit go, and which way will it blow?
- What are its heating capacities at 7 and 2 degrees?
- How will I reach the filters, and is a self-cleaning filter model worth it here?
- How loud is it inside? Noise figures on the label are optional in New Zealand, so ask if they're missing.
- What does the warranty cover on the compressor? LG's warranty, for one, adds a five-year parts-only compressor warranty for its high wall splits.
- Who makes the electrical connection, and when will I get the Certificate of Compliance?
Your part, and the installer's
You can
- Decide which room you most want warm, and at what times.
- Clean the filters as your manual describes.
- Keep the outdoor unit clear of plants and clutter.
- Use the timer so it isn't heating an empty house.
Leave to a licensed installer
- Choosing the wall and fixing the bracket level.
- Drilling and sealing the hole for the pipes and drain.
- All refrigerant pipework and charging.
- The electrical connection and its Certificate of Compliance.
What we'd do
Our take
For one living area, a high-wall unit is where we'd start, and we'd spend longer choosing the wall than the brand. Stand where you sit on a winter night and picture the airflow. If the only free wall is in a corner, or nobody at home can reach the filters, we'd look at a floor console instead. A heat pump installation specialist puts these units up every week, so ask them to show you why they've chosen the spot they have.