With the ever-increasing emphasis on protecting resources for future generations, hydronic underfloor heating offers a comfortable, long-term solution that is arguably the most sustainable option for home heating when paired with a heat pump water heater. This approximately 300m² Coatesville home is a beautifully presented example of an energy-efficient underfloor solution using a low energy input from electricity (around 80% from renewable sources in NZ).

This home was the owners’ third time building from scratch. Their first home incorporated gas heating. The second house used Champion Heating who installed a 7GP30Ub24-3 Duoheat heat pump to heat the pool and underfloor. This time it was an easy decision to use Tony Champion again. He recommended a 7GUb16-1 Performance Plus Digi Scroll heat pump for the underfloor. Two heat pumps are sometimes used to minimise heat loss that occurs over long distances for a house of this size. The owners wanted to hide the heat pump, so only one pump was used with the mains flow and return pipes protected in an insulated duct, trenched underground to reduce heat loss and allow the heat pump to be concealed on the far side of the barn.

The house sits on a Ribraft floor comprised of polystyrene pods that insulate between the ground and concrete. It features tile, wood and carpet floor coverings in different areas of the house. To capitalise on the energy efficiency offered by this system, the home is divided into thermostatically controlled zones with individual control over each zone.

Special considerations are required for each floor covering. While a tiled or polished concrete floor is relatively straightforward and provides good heat transfer, a floor that is carpeted must have a low tog rating to ensure heat can from easily flow from the slab beneath. Wooden floors require moisture to be dried out of the concrete before the floor is laid so the timber does not warp when heat is released from the concrete for the first time. A slab thermostat was installed to maintain a constant temperature preventing expansion and contraction of the wood. Each floor covering was circuited separately to accommodate the different heat transfer rates. The Digi Scroll technology in the heat pump provides for this with a variable kW output that can reduce running costs.

The owners have now moved in and are 100% satisfied with the results. They happily recommend Champion Heating and the Performance Plus heat pump from Hot Water Heat Pumps Ltd.