Central heating means one system warms the whole house, not just the lounge. In New Zealand it’s still unusual: a BRANZ survey of 560 houses found it in fewer than 5% of them. Part of the reason is that so many Kiwi homes leak heat, and heating every room in a leaky house gets expensive fast. If your house holds its heat, though, a heat pump can do the job three ways.
What is the best central heating in NZ?
There isn’t one best system. There’s a best fit for your house. These are the three heat pump options:
- Ducted: one hidden indoor unit blows warm air through ducts to a grille in each room.
- Multi-room (multi-split): one outdoor unit runs a separate indoor unit in each room.
- Air-to-water (hydronic): a heat pump warms water, which flows through radiators or pipes under the floor.
All three use an outdoor unit that takes heat from the outside air. The electricity runs the compressor and moves the heat. It doesn’t make the heat, which is why a heat pump gives out more heat than the power it uses.
How does a ducted heat pump heat the whole house?
A ducted system has one larger indoor unit in the ceiling or under the floor. Insulated ducts carry warm air to a flush grille in each room, and a return air grille draws air back through a filter to the unit. All you see inside are the grilles and a wall controller. Ducted systems suit new builds and can be retrofitted into existing homes.
We compare ducted with wall units in detail in ducted vs high-wall heat pumps, including the ceiling space checks.
Can a multi-room heat pump heat the whole house?
Yes, if you’re happy with a unit in each room. A multi-room system pipes one outdoor unit to several indoor units, and some outdoor units take up to eight rooms. You can mix high-walls, floor consoles, cassettes and even a small ducted unit on the same system, and each room gets its own temperature.
It’s often the simplest whole-home option for a finished house, because there are no ducts or water pipes to run through floors. The trade-offs, like every room sharing one heating or cooling mode, are covered in single-room vs multi-room heat pumps.
How does an air-to-water heat pump work?
An air-to-water heat pump is the heat pump version of a boiler. The outdoor unit takes heat from the air and passes it into water. That warm water is pumped around the house to radiators, underfloor pipes or fan coil units. Many systems also heat your hot water cylinder, so one system does both jobs.
There are two layouts. A monobloc unit heats the water outside in one box. A split layout sends refrigerant to an indoor module, often called a hydrobox, which heats the water inside.
→ Related: Hot water heat pumps and how they work
Underfloor heating or radiators?
Underfloor heating runs warm water, at about 35 to 45°C, through pipes set in a concrete slab or screed, or fixed under a timber floor. The whole floor becomes a gentle heater with no cold spots and nothing on the walls. It suits open-plan homes with high studs and exposed ceilings, and it’s easiest to install while a new slab is being poured.
Radiators sit on the wall and heat up and cool down faster than a slab. Each one can have its own thermostatic valve, so you can set rooms differently. Radiators come in slim panels for modern homes and column styles that sit well in a villa. They need hotter water than underfloor heating, so the heat pump works a little harder.
What does your house need before you install central heating?
Ducted:
- room in the ceiling or under the floor for the indoor unit and ducts, plus access for servicing
- a spot for the return air grille
- well-insulated, sealed ducts, because leaky ducts lose heat on the way
- for larger capacities, a three-phase power supply
Multi-room:
- an outside wall or yard space for one outdoor unit
- a path for pipes from each room back to that unit
Air-to-water:
- a slab or floor you can lay pipes in, or wall space for a radiator in each room
- room for a hot water cylinder, or an existing cylinder the system can connect to
- an indoor wall for the hydrobox, if you choose a split layout
- in some setups, a buffer tank and circulation pump, which some packaged underfloor units include
Ask the installer exactly which of these your quote assumes.
How does zoning work with central heating?
All three systems let you heat some rooms and not others. Ducted systems use motorised dampers in the ducts to split the house into zones, often a day zone for living areas and a night zone for bedrooms. Zoning lets a smaller unit do the job. Multi-room systems give each room its own controller. Air-to-water systems use room thermostats on underfloor zones or valves on each radiator, and the controller can adjust the water temperature as the weather changes.
Comfort feels different, too. Ducted and multi-room heat with moving air, which responds quickly. Underfloor and radiators heat without blown air, so they’re quiet and stir up less dust. Water-based systems are slower to respond, especially a heated slab, so set the timer to start them well before you need the warmth.
Which central heating system suits your house?
- New build or major renovation: any of the three. It’s the best time for underfloor heating in the slab or ducts in an open ceiling.
- Finished house with good roof space: ducted is a strong option.
- Finished house with little ceiling space, or a townhouse: multi-room is usually simplest.
- Character villa or bungalow: radiators can be retrofitted and suit the style.
- Frosty inland towns like Alexandra, Twizel or Taupō: check the model’s cold-weather rating. Some air-to-water models hold their rated heating output down to -15°C, and some carry a backup heater for the coldest days.
What size heat pump you need explains how to check the capacity on a quote, and heat pump cost in NZ covers what changes the price.
→ Related: Best heat pumps for cold NZ climates
Should you insulate before you install central heating?
Get the insulation right first. A lot of energy is lost heating uninsulated spaces, and that loss grows when you heat every room. If you’re adding central heating to an existing home, check the ceiling, underfloor and walls are insulated before you choose a system. A heat pump doesn’t replace good insulation.
→ Related: Healthy Homes heating standard explained
Heat pump, gas or wood central heating?
Gas boilers are mainly cost-effective where reticulated natural gas reaches your street. LPG boilers usually cost the most to run, and wood pellet central heating sits between natural gas and LPG. A heat pump system runs on electricity alone, so there’s no gas connection or fuel tank to keep up.
How do you find a central heating installer near you?
Browse installers who fit ducted heat pumps or multi-room systems, or pick your town to see who works near you. When you’re ready, get a quote for your place.