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Mt Barker - Off Grid

Heating Type: Radiators, Wood Fire.
Heat Source: Solar, Wood, Gas.
Other: Rotex


This stunning 200sq/m house in Mt Barker, Wanaka now boasts a brand new heating and hot water system. Originally used as a family holiday home, our clients came to us with the hope of turning it into their permanent residence one day if we could help them find a responsive and sustainable solution for heating and hot water.

Utilising an exciting combination of smart technologies and sustainable natural resources, this newly heated home now has all the comfort of a grid-connected section while harvesting the renewable energies available to the rural property.

“Just wanted to convey our thanks to you and your team for your contribution to our project. It has been, overall, as straightforward as it could possibly have been-although the complexities of an off-grid system have at times seemed daunting! Kurt and all the others have always been obliging and helpful-including with the ongoing fine-tuning of the system.”


The system we designed had to be sustainable, responsive and off-grid, so we highlighted the beautiful, rural location of the property, and put all natural resources to use. Our design incorporates solar power, a wood fired boiler, gas water heating and energy efficiency heat storage, and by installing underfloor heating, radiators and reliable hot water, we have successfully heated the entire home.

For energy efficiency and responsiveness, we installed a system that would provide a multitude of adjustable heating options. The main living, dining, kitchen, atrium/entry, library, hallway, mudroom, bathroom and en-suite are heated by underfloor pipe work to provide low temperature heating to the main areas. To provide flexibility to the heating, the three bedrooms have radiators that can provide a quick response when needed as not all of the rooms will be used. The wood fire provides another level of flexibility, heating the dining/kitchen, and there is an Escea gas fire in the living room for low energy, quick heat, or just for ambience if needed.

THE HEATING SYSTEM – Thermal Store/Wood Fire/Solar/Gas

We used a thermal store to create a central hub for all heating and hot water. The Rotex Sanicube thermal store can collect the energy from various sources and deliver the heated water to various locations/requirements. We installed solar hot water heating to provide hot water to the thermal store in summer, and we put in a wood-fired boiler to be the source of hot water in winter.

The wood fired boiler has an attractive glass front and looks the same as a normal freestanding fire, but it has the ability to heat water along all remaining three sides. We chose the Thermalux Linea fire, which is able to generate up to 20kW of hot water quickly and deliver up to 8kw of heat to the room. The heated water is delivered to the previously mentioned thermal store by a low energy pump (this can be done by gravity if close enough) and heats the thermal store directly without a heat exchanger.

The solar system is also connected to the thermal store as an additional/back-up/quick recovery heat source. The photovoltaic solar panels also provide all the energy to power the home, while batteries charged by the panels store extra power for the evenings. Any excess energy from the solar is directed to the thermal store to act in effect as another “battery”, utilising the excess energy to generate hot water.

The gas water heater makes up the final component of the heating system, connected to the thermal store and providing back-up hot water for when the solar and wood-fired water heating systems are lacking. Together, all components of the heating system ensure consistent and responsive hot water and heating year-round.


All power generation and consumption need to be monitored carefully to make sure the home can have continuous power; and careful selection of energy efficient appliances, LED lighting, low-energy pumps and gas cooking was required at the very beginning of the planning process with the clients and architects.

The architects ensured the home has high insulation values, with R4 in the walls and R5 in the ceilings, and high quality windows and doors to minimise heat loss. The orientation of the home also maximises the sun available in summer and winter.


To further the sustainability of the home’s heating system, most of the rainwater from the roof is collected in an in-ground water tank to use for domestic and irrigation purposes. This helps minimise the use of the solar bore water pump.


If you’re interested in any of the systems described in this case study, reach out and we can discuss options to help you heat your own home!

Thermalux linea 20 wood boiler

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