Which type of heat pump suits the room?
Consumer NZ says high-wall units are the most common type of heat pump in New Zealand. They sit near the ceiling and move enough air to heat a room evenly, ideally aimed across the room rather than at the couch.
A floor console sits against a wall at floor level. Consumer NZ says its filters are a breeze to clean, handy if reaching up to a high-wall unit would be hard. BRANZ is blunt that the types aren't interchangeable, and Mitsubishi Electric NZ says "Low Wall" installations of its high wall units aren't covered by its warranty.
For several rooms, a ducted heat pump or a multi-room heat pump (one outdoor unit running several indoor units) is the usual alternative to a separate unit in each room.
Getting the size right
Size means heating capacity in kilowatts, which Consumer NZ calls the most important specification. EECA says to size on the 7 degree heating figure if the unit will mostly heat. Where winter nights reach 2 degrees or colder, check that the capacity at 2 degrees is at least the figure at 7.
Mitsubishi Electric NZ says places with sub-zero winters, like most of the South Island, need a larger heat pump or an upgraded model. BRANZ adds that an oversized unit keeps cycling on and off, and an undersized one runs constantly and defrosts often. It's also plain that heat pumps don't replace good insulation. Start with our size calculator and sizing guide.
Where the indoor and outdoor units should go
In one BRANZ survey, over a fifth of households said their heat pump wasn't in the ideal spot. A unit tucked into a corner may only heat part of the room.
Outside, BRANZ wants at least 500 mm clear in front of the outdoor unit's air inlet and outlet, 100 mm on the other sides and 100 mm off the ground. It suggests the warmest wall, such as a north or west facing one, away from bedrooms.
Noise limits for outdoor units sit in each council's district plan, and Mitsubishi Electric's NZ warranty excludes problems from units installed close to neighbouring boundaries. Near the sea or in a geothermal area, BRANZ says outdoor units need extra anti-corrosive coatings, so settle that before you sign.
What happens on install day
The indoor unit goes up
A hole goes through the wall for the pipes, cable and drain. Schedule 1 of the Building Act 2004 lets a hole of up to 300 millimetres through an existing house of up to 3 storeys go ahead without a building consent.
The outdoor unit is set in place
On a pad or a bracket, with its clearances, and where a technician can reach it later.
Pipes and the drain are run
The condensate drain (the hose that carries water from the indoor unit) should end in a drain or a garden, BRANZ says, not on a path.
A registered electrician connects it
This is prescribed electrical work, so only a registered and licensed electrical worker can do it. They must give you a Certificate of Compliance no later than 20 days after the work. You should also get an Electrical Safety Certificate, and WorkSafe's form says to keep it for at least 7 years.
Who can legally do the work, and do you need a consent?
Tenancy Services' heating guide says heat pumps need a licensed electrician for installation. A January 2020 release for the Electrical Workers Registration Board described a heat pump business owner who wasn't licensed to do the electrical connection. Look the electrician up on the EWRB register.
Refrigerant isn't set by a licensing law. In 2011 the Commerce Commission authorised an industry arrangement on who can buy it. Wholesalers may sell refrigerant only to buyers with a Refrigerant Licence from the Refrigerant License Trust Board, or an EPA Approved Handler or Approved Filler test certificate.
Many installs need no building consent: Christchurch City Council says a heat pump doesn't, provided registered electricians do the work and certify it. The Building Code, the district plan and any body corporate rules still apply. Our consents and noise guide has the detail.
Your part, and the installer's
You can
- Work out which rooms you really heat, and when.
- Check how close a possible outdoor spot is to a neighbour's bedroom.
- Compare the 7 and 2 degree heating figures on the Zoned Energy Rating Label.
- Once it's running, clean the filters as the manual says and keep the outdoor unit clear.
Leave to a licensed installer
- Sizing from the room, your insulation and your winter lows.
- All refrigerant pipework and charging.
- The electrical connection and the Certificate of Compliance.
- Sealing the wall penetration, setting the drain, and any corrosion protection.
What a good written quote covers
- The model of every unit, with its heating capacity at 7 and 2 degrees.
- Where each unit goes, and how the outdoor unit is mounted.
- Who does the electrical connection, and that you'll get a CoC and an ESC.
- Corrosion protection, if you're near the coast or in a geothermal area.
- What the brand's warranty needs. Rinnai NZ, for example, says installation must be by a Rinnai accredited installer.
- Whether it's a quote or an estimate. Consumer Protection says a quote is a set price that can't rise once accepted unless the work changes.
What we'd do
What we'd do
We'd get the room sized before looking at brochures, and where nights get frosty we'd weigh the 2 degree heating figure as heavily as the headline one. We'd refuse an outdoor spot boxed in under a deck or outside a neighbour's bedroom. Then we'd hand it to someone who installs heat pumps every week, so the drain, clearances and pipe run are right first time.