An introduction to hydronic heating systems in New Zealand: A comfortable, efficient and future-proof way of heating your home

Hydronic heating systems are becoming rapidly popular among Kiwi homeowners with growing demand for smarter, healthier and more comfortable energy-efficient heating solutions.

A hydronic system offers the choice of selecting your preferred way of heating, either immersing in all-around warmth from underfloor heating, the quiet radiator heating, or the forced heating and cooling from a fan coil unit.

Whether you’re building new, renovating, or replacing outdated heating equipment, here’s a clear and practical guide to understanding hydronic home heating and why it’s becoming so popular in Aotearoa.

What is hydronic heating?

Hydronic heating uses warm water (not air!) to warm your home. The system consists of:

• A heat source (heat pump, gas boiler, oil or wood burner)

• A network of insulated pipes throughout the home

• A heating circuit such as underfloor heating, radiators, or fan coil units

The water is heated in the heat source and circulated through your chosen system, delivering steady, comfortable and even warmth throughout your home.

Hydronic underfloor heating

Why are homeowners choosing hydronic systems?

Underfloor heating

An underfloor system is a slow, low-temperature heating system. It is installed in new builds with a concrete slab floor. The water pipes in the concrete are zoned room-by-room to control the various areas. Floors in living areas are heated from autumn until spring at a max temperature of 29°. Bedroom areas are usually a few degrees lower.

Radiator heating

A radiator system can be installed in new and existing homes. The radiators operate at a higher water temperature. The valve at the radiator controls the water flow through the radiator. There are various valves available these days: manual, thermostatic, and motorised with app-controlled operation.

Fan coil units

A fan coil unit is a radiator with a fan and a drain pan. The fan forces air through the fan coil unit and quickly heats up the room. When a heat pump is used as the heat source, it can be set for cooling as well. Any condensation water will be drained by the drain pan.

Fan coil units are available in various models:

• Floor models which look like a radiator

• Ceiling-concealed units which circulate the air through grilles and ducting in either the ceiling or the floor

The fan coil units are controlled individually, either manually or with an app.

Where does Calitec Hydronic Home Systems fit in?

For homeowners looking for a compact, modern solution, Calitec provides a fully integrated hydronic home system that combines both home heating/cooling and domestic hot water in one unit.

This means:

• One outdoor heat pump unit powering both the hydronics system + hot water cylinder

• A neat and compact installation with fewer components

• High overall efficiency

• Reduced running costs and long-term sustainability

It’s a streamlined, future-proof approach ideal for New Zealand homes, whether you're planning a new build. We have our complete model which incorporates all the required parts such as a buffer tank, expansion tank, circulation pumps and 3-way valve fitted and tested in the heat pump outdoor unit. Ready to connect to your heating circuit and your (or our) hot water cylinder.

If you are only looking to replace your aged oil, gas, wood or other burner with an energy-efficient heat pump, we have a basic model which can seamlessly connect to your existing heating circuit. And if you haven’t already, you can connect your hot water cylinder to it as well.

More information about our Calitec Hydronic Home Systems, click here.

Underfloor heating vs radiators vs fan coils: Which is better?

All three options work well in New Zealand homes. The best choice depends on your build and your comfort preferences.

Underfloor Heating

• Ideal for new builds

• Invisible heating with no wall units

• Perfect for hard floors, e.g. polished concrete or tiles

• Even heat distribution

Radiators

• Great for renovations or retrofits

• Heat up quickly

• Stylish designs to match any interior

• Simple to install with minimal disruption

Fan coil units

• Provide fast heating (and cooling!)

• Ideal for rooms needing quick temperature changes

• Compact wall-mounted and ceiling-concealed options available

How heat pumps improve hydronic heating

Heat pumps are becoming the preferred heat source because a heat pump hydronic system can reduce heating costs dramatically compared to electric or gas-based systems, even in NZ winters. They are also able to heat both domestic hot water and hydronic circuits with one system.

Is hydronic heating right for your home?

Here are some questions to help you decide:

• Are you planning a new build or major renovation?

• Do you want efficient, silent, allergy-friendly heating?

• Do you prefer stable, consistent warmth instead of quick bursts?

• Are you looking for a long-term, cost-saving heating solution?

If the answer is yes to any of these, hydronic heating is worth investigating.

The future of home heating in New Zealand

As energy prices rise and sustainability becomes essential, more Kiwi families are turning to systems that provide high comfort with low running costs. Hydronic heating, especially when paired with a modern heat pump, fits perfectly into this shift.

Hydronic systems are no longer only found in high-end homes. It’s now one of the smartest ways to heat modern New Zealand houses, offering comfort, efficiency and durability that traditional systems struggle to match.