Hydronic heating

The warmest floors in New Zealand. Is it worth it?

Hydronic (wet) heating pumps warm water through your floors or radiators for silent, even warmth with no wall-mounted units. Here is the honest breakdown for Kiwi homeowners — costs, running costs, new build vs retrofit, and when a multi-split heat pump is the smarter call.

Get a free home audit first NZ-specific costs Independent advice
$25k–$40k
New build (installed)
$35k–$55k
Retrofit (radiators)
COP 3–4
Air-to-water efficiency
~$0.11/kWh
Delivered heat cost

What is hydronic heating?

Hydronic heating circulates warm water through a closed loop of pipes — either buried in a concrete slab (in-slab underfloor) or feeding panel radiators mounted on walls. The heat source is typically an air-to-water heat pump sitting outside, though gas boilers and wetbacks are also used.

The result is radiant warmth — heat that rises evenly from the floor or radiates gently from walls. No fan noise, no dry air, no dust circulation, no plastic boxes on your walls. It is widely considered the gold standard for home comfort in cold climates worldwide.

How the system fits together
  1. Heat source — air-to-water heat pump (outdoor unit)
  2. Buffer tank — stores heated water, smooths demand
  3. Manifold — distributes water to each zone
  4. Distribution — in-slab PEX loops or wall radiators
  5. Controls — per-room thermostats + weather compensation

Pros and cons for NZ homes

Advantages
  • Even, radiant warmth — no hot/cold pockets
  • Silent — no fan noise anywhere in the house
  • Invisible — no indoor head units on walls
  • Zoned — each room gets its own thermostat
  • Better for allergies and asthma (no forced air)
  • Can heat domestic hot water from the same unit
  • Very long lifespan — PEX loops last 50+ years
Disadvantages
  • High upfront cost — 2-3x a multi-split heat pump system
  • In-slab loops only possible before the concrete pour
  • Slower response time — takes 1-2 hours to warm a cold slab
  • Retrofit is invasive and expensive (radiator pipework through walls)
  • Fewer NZ installers — specialist skill, longer lead times
  • No cooling (unless you add fan-coil units or a separate system)
  • Overkill for mild NZ climates (Auckland, Northland)

New build vs retrofit — the cost gap

Component New build (180 m²) Retrofit (180 m²)
Heat pump unit (8–16 kW air-to-water) $8,000–$18,000 $8,000–$18,000
Distribution In-slab PEX loops: $5,000–$10,000 Panel radiators (6–8 rooms): $9,000–$18,000
Buffer tank + manifold + controls $4,000–$6,000 $4,000–$6,000
Pipework / labour Included in slab pour $5,000–$10,000 (routing through walls/floors)
Total installed $25,000–$40,000 $35,000–$55,000+

Running cost comparison

Heating method Cost per kWh of delivered heat Annual cost (180 m², Christchurch)
Hydronic (air-to-water HP) ~$0.11/kWh ~$1,100–$1,500
Air-to-air heat pump ~$0.10/kWh ~$1,000–$1,400
Gas boiler (piped gas) ~$0.14/kWh ~$1,400–$1,900
Electric panel heaters ~$0.39/kWh ~$3,900–$5,200

Based on 2026 NZ average power rate of ~$0.39/kWh. Actual costs vary by region, insulation level and thermostat habits.

Air-to-water heat pump brands available in NZ

Daikin Altherma

Most widely installed in NZ. Good parts availability, strong installer network.

Mitsubishi Ecodan

Strong cold-climate performance. Popular in the South Island and Central Plateau.

Carrier Aquasnap

Trusted commercial pedigree now in residential. Reliable, efficient and backed by a strong NZ service network.

Panasonic Aquarea

Available through specialist importers. Compact outdoor unit, Wi-Fi control.

Should you go hydronic? A quick decision guide

Hydronic is a strong choice if:
  • You are building a new home (in-slab is cheap before the pour)
  • You are doing a major renovation with floors or walls open
  • You live in a cold NZ region (Queenstown, Central Otago, Canterbury high country)
  • Someone in the household has asthma, allergies or dust sensitivity
  • You want whole-home heating with nothing visible on the walls
  • Budget is not the primary constraint
A multi-split heat pump is probably better if:
  • You have an existing home and are not renovating
  • You are in a mild climate (Auckland, Northland, Bay of Plenty)
  • Budget is tight — a multi-split costs $8k–$15k vs $25k–$55k
  • You want cooling as well as heating
  • You want fast heat-up (minutes, not hours)

Not sure? Our free home audit considers your climate zone, house size, year of build and current setup to recommend the right approach.

Hydronic tips and advice

Hydronic heating — frequently asked

A new-build system with in-slab loops and an air-to-water heat pump typically costs $25,000–$40,000 installed for a 180 m² home. A retrofit with wall-mounted panel radiators runs $35,000–$55,000+ because routing pipework through existing walls and floors is labour-intensive.

Running costs are similar. An air-to-water heat pump (hydronic) delivers heat at roughly $0.11/kWh, while an air-to-air heat pump costs about $0.10/kWh. The difference is comfort: hydronic gives silent, even radiant warmth with no moving air. But the upfront cost is 2-3 times higher.

Yes, but it is expensive. In-slab loops are only possible before the concrete pour, so retrofits use panel radiators mounted on walls, fed by PEX pipes routed through the wall cavity or under the floor. Expect $35,000–$55,000+ for a full system in a 3-4 bedroom home.

It works, but it is overkill for most Auckland homes. Auckland's mild climate means you only need significant heating 3-4 months of the year. A well-sized heat pump system at a third of the cost is usually the better investment. Hydronic makes more sense in colder regions like Canterbury, Otago and the Central Plateau.

It is the same technology as the heat pump on your wall — it extracts heat from outdoor air using a refrigerant cycle. The difference is that instead of blowing warm air into the room, it heats water that circulates through underfloor loops or radiators. Main brands in NZ include Daikin Altherma, Mitsubishi Ecodan, Carrier Aquasnap and Panasonic Aquarea.
Not sure if hydronic is right for your home?

Run our free 5-minute home energy audit. We will factor in your climate zone, house size, year of build and current heating setup to recommend whether hydronic, heat pumps or a combination makes the most sense for your property.

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