Centralised heating systems:
– Centralised supplementary heating to 80 deg C.

Where a particular site suits a centralised heating system, and the peak heating demand of the existing system requires 80 deg C water, we integrate a thermal storage into the system, to take advantage of low electricity pricing overnight. This approach avoids the need to upgrade the existing heating system by adding additional radiators or fan-coils and allows the transient peak heating period demand to be met through supply of 80 deg C heated water. With heating demand during the day decreasing as ambient temperature increases, the supply of 80 deg C water temperature can be reduced, followed by direct heating with heat-pump water heating at 55-60 deg C. The control and use of the thermal store, where required is automated. During shoulder seasons, the heat-pump would directly supply the heating load, without the need for supplementary heating. Outside of peak heating demand periods, the thermal store is used to reduce heating startup times. 

Centralised heating systems:
– Supplementary heating with fan coils.

Where a particular site suits a centralised heating system, and there is ready access to ceiling space in the heated spaces, it is proposed to provide supplementary heating using ducted fan coils to meet peak heating demand. This approach maximises the efficiency of the heat-pumps, and allows greater control of the indoor temperature through control of the output of the fan coil.

This approach was successfully demonstrated during the boiler replacement project at a Northland hospital, with a variable primary flow heat-pump water connected to the existing flow / return header.

Distributed heating systems:
– Supplementary heating with fan coils.

Generally when transitioning from a centralised heating system to a distributed system, the water temperature supplied to the heating loop can be reduced to account for the reduction in distribution losses within the system, as the heating source is considerably closer to the point of demand. This approach also allows heating supply to be more directly matched with the load, for the zone being heated.

This approach has been demonstrated successfully a second hospital boiler replacement project, and has the advantage of not degrading the energy efficiency of the overall system by requiring an elevated operating temperature that is only required to meet the design heating condition.

Electric Boilers and Thermal Stores.

Where specific site limitations prevent the use of heat-pump water heaters, we are able to design and supply electric boilers. These boilers are available at up to 410 kW capacity, and have been widely used throughout New Zealand for many years. Our preference however, is to make use of heat-pump water heating technology where possible for the greater efficiency of these systems when used within their operating limits.
We also recognise the benefits of the integration of thermal stores into a water heating system to provide both a store of higher temperature water, and to avoid electricity consumption during peak demand periods where the electricity tariffs are elevated. We can integrate a range of thermal stores into our design