Wanaka location, 160sq/m floor size, 45sq/m attic, 34sq/m garage, 1 permanent occupant

Our client is a architectural designer and recently built her own home in Wanaka. A sustainable, environmentally friendly design was the key for the entire house build, which was to incorporate central heating and energy into one integrated system. The client had specified  a Stanley Comeragh wood range/boiler (similar to an AGA), as a feature in the kitchen as a functional part of the heating system, so the design followed from that specification. We also did the plumbing and drainage for this home, completing our total package service. 

> 500L Rotex Thermal Store - Wetback, Solar Thermal and Electric Elements
> Radiators x 5
Wood Range with 13.8kw Wetback System
> Solar Thermal Panels - 3 x Solimpeks ALS 2.5 Panels
> Heatmiser Neostat Thermostat
> 2kw Solar PV System - 8 x 250W Micro Inverter Panels
> Wood Fire

The central heating and domestic hot water system revolves around the Rotex. The Rotex is a 500L thermal store which collects the energy from various sources and disperses the heated water to the central heating (radiators) and domestic hot water. The system energy sources are;

  1. Wetback from Stanley Comeragh Stove;

  2. Solar Thermal Collectors x 3;

  3. Electric Element with 2kw PV Solar.

The Stanley Comeragh Boiler will produce hot water when the fire is on via the wetback. It will contribute considerably towards the heating of the Rotex.

The radiators act as a ‘heat dump’ for the Rotex, so if the fire is on and the Rotex tank gets above 70°c and the hot water is not being used for domestic purposes, the central heating pump will pump water to the radiators, which will come on as per the settings on the TRV’s. The radiators are controlled individually, by the thermostatic radiator valves (TRV’s) located on each radiator. The radiators are adjusted in temperature or turned off completely by the valves. If the radiators are turned off completely (e.g. throughout summer months), the central heating pump circulates the hot water for the central heating system through the bypass, rather than to the radiators.

The solar panels also contribute to the heating of the Rotex during sunlight hours. The solar thermal panels work by collecting heat directly from the thermal panels and transferring it to the hot water cylinder through a flow and return. As the solar thermal panels may bring the Rotex over 70°c during sunnier months, the radiators will need to be turned off at the individual thermostats to ensure they don’t come on.

The Rotex also has an electric heating element which will draw energy from the PV solar or from the grid to heat water for tank if the other heat sources have not generated enough heat to bring it up to 60°c. If the Rotex is already at the required temperature, any excess power generated by the panels will be exported back to the grid and show as a credit on the clients power bill.

The LTDC controller, located in the plantroom controls the heating system parameters, e.g. monitoring the Rotex temperature and determining how the hot water is used. 


Unknown at this point, still a new system. 

> Technician maintenance - this is a very low maintenance system, however we recommend a technician checks the overall system operation pre-winter, this costs approximately $200 + GST and includes topping up inhibitor, balancing radiators and checking system pressure. Solar Thermal panels need virtually no maintenance (a glycol check every 5 years is recommended) and Solar PV requires no maintenance. 
> Client maintenance - the pressure in the system needs to be kept topped up for the system to operate. Occasionally, this may drop and need to be topped up. This is a 10 minute task and we provide our clients with an manual specific to their system with instructions on how to do this.

Download information sheet on the Rotex Sanicube Thermal Store.


Download brochure on Heatmiser range or visit website:


Download brochure on Stanley Comeragh Wood Range