Using Heat Pumps for Underfloor Heating

Date: Sep 11, 2018 - 1:10 pm

Underfloor heating or radiant in-floor heating is increasing in popularity among Kiwi households due to its many advantages. Not only are heated floors lovely to walk on, but they are also economical, comfortable and energy efficient to run.


Unlike other heating methods, radiant underfloor heating encourages heat to rise up through a space via convection, rather than forcing it down. In-floor heating can either take the form of hydronic heating or electric resistance heating. We’ll focus on the first one.

Hydronic heating involves laying a network of pipes onto the subfloor and circulating a heating fluid through the piping. The heated fluid radiates heat into your floors, warming your home evenly and comfortably. Hydronic heating operates silently, which is another plus.

The fluid can be heated in various ways: by using a heat pump, using fossil fuels or electricity by means of a boiler heating unit. Heat pumps generate hot water at around 40oC, which is ideal for heated floors. On the other hand, gas and oil boilers heat water to 65-85oC, which will scald your feet. Using these systems will require mixing hot and cold water to bring the temperature down to a comfortable level, which is highly inefficient.

Air-to-water heat pumps take the heat from ambient/outside air and transfer the heat into the water via a heat exchanger in the cylinder. Some heat pump systems can be configured to provide part of the energy needed for domestic water heating.

With the integration of a heat pump, your underfloor heating system will have the potential for zoned control. This means that rooms can be heated on an on-demand basis, helping you to cut down your energy consumption. In addition, heat pumps offer the versatility of switching between heating and cooling modes for year-round comfort.

Heat pumps generally use less energy to maintain the heat when the target temperature is reached. Some units can control the temperature as accurately as 0.5oC. When there is a big difference between the desired temperature and the actual temperature, some heat pumps automatically adjust to a higher frequency to increase the temperature rapidly.

Modern heat pump technology also has a smart-defrost feature that allows faster recovery by reducing defrosting time and extending heating time. This further enhances heating efficiency. And since they are designed to work well into the winter season, heat pumps typically have inbuilt anti-freeze protection along with other protection controls, such as water flow switch protection, compressor overload protection, high/low pressure protection.


In summary, underfloor heating powered by a heat pump is a convenient and efficient way to heat your home.


Underfloor heating is often integrated in the design of a new home build for practical reasons. It is easier to lay the pipes before the floors are laid than to retrofit them.

In existing homes, casting the pipes is a lot trickier as there are items of furniture and fittings in the way and some floors can be difficult to work with. For elevated homes, the pipes can be retrofitted via “diffusers” spread below your timber floor. For concrete slab floors, the pipe is attached to a mesh profile and topped with a concrete screed that may be tiled or carpeted.

As you can imagine, a more complex installation means higher upfront costs. But if you think about the comfort and long-term energy savings, a heat pump-powered underfloor heating system can be worth the investment.

For more information or inquiries, please contact us on 0800 443 284.