Top tips for heat pumps

Heat pumps are very popular but it's important to choose an efficient model and use it properly, according to EECA ENERGYWISE. Technical Expert Christian Hoerning says heat pumps can be very economic if used correctly; they are convenient and produce instant heat.

Types of heat pump

  • Single-split systems are the most common heat pumps in New Zealand - they are air-to-air, with one indoor unit connected to an outdoor unit. These systems are designed to heat just the room that they are installed in, not the whole house. While leaving internal doors open may allow some of the heated air to travel into other rooms, in most houses this does not work very well, particularly if there is a hallway in between, if there are high ceilings or if the house needs a lot of heating.
  • Multi-split heat pumps are designed to heat multiple rooms - and consist of one outdoor unit serving multiple indoor units installed in different rooms of the house.
  • Ducted heat pumps provide central heating - by blowing heated air through ducts into multiple rooms of a house. While some can only be controlled centrally, others allow you to choose which rooms or groups of rooms you want to be heated at any given time (zoning). For example, you may only want to have your bedrooms heated overnight.

Choosing an efficient model

All heat pumps have an Energy Rating Label that helps you compare the efficiency of similar sized models. The more stars, the more energy efficient a unit is - red stars are for heating efficiency and blue stars are for cooling.

A heat pump label has two numbers that can tell you more about the heat pump's performance:

  • capacity output - the amount of heating or cooling (kW) you will get out of the heat pump (at its rated capacity, at 7˚C outdoors)
  • power input - the amount of power the heat pump uses (kW) to produce the cool or hot air.

Some heat pumps struggle to perform when it’s just above freezing point outside. Ask your supplier for a heat pump that will perform well in your region. A good quality unit - sized and installed correctly - should perform effectively down to minus 15°C.

Heat pump checklist

  • Insulate first - starting with your ceiling and floor. You'll be able to buy a smaller heat pump and your home will be cheaper to heat and cool effectively. Low-income rentals may be eligible for a subsidy through Warm Up New Zealand: Healthy Homes.
  • Choose a quality brand - from a reputable supplier that offers at least a 5-year warranty on parts and labour.
  • Make sure it's correctly sized - for the room you want to heat. If it's too small, it may cost you more to run and will struggle to provide enough heat when you most need it. Your supplier will be able to discuss this with you.
  • Make sure it is well-installed - ask your installer if they comply with the EECA Good practice guide to heat pump installation. Correct location and installation of both outdoor and indoor units is essential for optimum performance and for avoiding draughts and noise nuisance.
  • Make sure it’s right for your environment - in geothermal areas or coastal areas, heat pumps need to have suitable protection against corrosion. Ask your supplier about environmental considerations in your area.

Avoid wasting electricity and money

  • Only heat when you need it - don't leave your heat pump on all day if you're not there.  Use the timer to turn on the heat pump shortly before you get home and turn it off when you don’t need it.
  • Only heat the space you're actually using - shut doors and curtains to keep the heat in.
  • Set the thermostat to a healthy temperature - aim for 18 to 20ºC. High thermostat settings cause high electricity use. Inadequate heating can lead to mould growth and dampness.
  • Clean the filter regularly - inside and outside, as per the manufacturer's instructions.

Media enquiries:

Penny St John, Senior Communication Adviser, EECA

Phone: 027 687 3123

Email: penny.stjohn@eeca.govt.nz