High-wall heat pumps for Palmerston North homes

A high-wall handles a Manawatū winter perfectly well, and three things decide whether it's right for your room: how much capacity it needs once the glazing and the cold that settles in this valley are both accounted for, whether there's a clear stretch of wall up high for it to blow down from, and whether the outdoor unit can sit somewhere the westerly isn't hitting it head-on.

How much does a high-wall heat pump cost in Palmerston North?

Fitted, a bedroom or small room runs about $2,500 to $3,500. A main living area is $3,200 to $4,500, and a large or open-plan space $4,500 to $6,500. That's roughly 2.5kW, 5 to 6kW and 7 to 8kW of capacity.

Those are prices for the job finished. They cover the indoor and outdoor units, the mounts, the pipework, the drainage, the electrical work and the labour to fit it tidily and test it. A cheaper number online will be the unit on its own.

What separates one quote from another is the building rather than the brand. A straight external wall, where the outdoor unit hangs behind the indoor one, is a quick job. A long route through a cavity, or a two-storey place up in Highbury, takes longer and uses more material.

One thing you don't pay for here

There's no salt in the air this far inland, so none of your money goes into coated units, corrosion-resistant brackets or the shorter replacement cycle the coastal towns budget for. That's a genuine saving, and it means the sensible place to spend is capacity instead.

Put your room through the sizing calculator for a capacity and a figure, or read the installation cost page for what moves a quote.

Why the westerly matters as much as the frost

Palmerston North sits in a valley basin, so cold air drains off the ranges and settles here overnight. That alone makes for frostier mornings than the coast gets. What people don't expect is that the wind makes it worse rather than better.

The outdoor unit is a copper coil threaded through hundreds of thin aluminium fins. In heating mode that coil runs colder than the air around it, because it's pulling warmth out of that air and sending it inside. Any moisture in the air freezes onto it, and every so often the unit has to stop heating your room and melt the frost off itself before it can carry on.

Now put a westerly straight into the front of it. More damp air crosses the coil every minute, so frost forms faster and the unit runs that defrost cycle more often. Each one is a few minutes when your room isn't being heated, and on a cold windy morning those add up into a house that never quite catches up.

The fix is position rather than a bigger unit. Out of the direct westerly, against a wall that shelters it, with air still able to move freely around it. On the exposed sections out toward Whakarongo, Ashhurst and the open Awapuni flats that sometimes means putting it on a different side of the house than the short route would suggest, and it's worth the extra pipework.

What it must not have is a solid enclosure built round it to keep the wind off. That stops it shedding and gathering heat altogether, which costs more than the wind ever did, and it blocks access for the yearly service.

Sizing one for an older villa or a newer build

The published guide is 2.5kW for a bedroom, 5 to 6kW for an ordinary lounge and 7 to 8kW for a large or open-plan space. In Palmerston North the question is usually whether your house takes the step up, and a lot of them do.

The older timber villas around Terrace End, West End and Hokowhitu are single glazed with high studs, and both of those work against you. A single pane sheds heat roughly ten times faster than the wall around it, so on a frosty night the room is losing warmth about as fast as a modest unit can supply it. And because the ceilings are high, the warmth that does arrive collects above head height while the air down where you're sitting stays cold.

That's the case for a floor console in those houses. It puts the same heat in at skirting level, so it reaches you on the way up instead of after it's gathered at the ceiling.

The newer open-plan builds at Kelvin Grove and out around Feilding are the easier job. Better insulation, fewer internal walls, one connected space, so a single well-sized high-wall reaches all of it.

Going big to be safe causes a different problem. An oversized unit hits the set temperature in a rush and shuts down before it's pulled much moisture out of the air, and in a damp Manawatū winter that leaves the room warm and still clammy.

Will one heat the whole house?

One in the main living area with the internal doors open carries a compact house further than people expect, and for a single living space it's usually all that gets fitted.

It can't turn a corner though, and it won't push heat down a hallway into the bedrooms. If those matter you're choosing between a second unit and a multi-split, which runs several indoor heads off one outdoor unit. On a windy section that has a second advantage worth having: one outdoor position to get right instead of three. The price follows the number of heads and how far apart they are, so it's worked out on site.

For a bigger newer home, ducted feeds every room through ceiling vents and shows nothing but the grilles, and a ceiling cassette suits a large flat-ceilinged room where a wall unit would look bulky and heat unevenly.

Whatever goes in is reverse-cycle, so the same box cools in summer. Manawatū summers aren't extreme, but a west-facing lounge with the afternoon sun on it gets uncomfortable, and there's nothing extra to buy for it.

Still weighing it up? Types of heat pump puts a high-wall beside a floor console, a ceiling cassette, a multi-split and ducted, and heat pump installation covers how the day runs. For a number on your own room, get a free quote.