Warm water central heating / Diesel, Gas and Heatpumps

Warm water central heating systems use water to distribute heat thoroughly and evenly around the home. Water transfers energy at a much higher rate than air. making these systems very efficient.

Combusting boilers burn a fuel–gas, diesel, or wood pellets/logs—and transfer energy into
water. They are ideally used to heat radiators, which usually require high temperatures.
In New Zealand, gas and diesel-fired boilers are the most common types. There is little difference between gas- and diesel-fired boilers in terms of performance, safety, and technical or spatial requirements  Both are highly efficient and clean burning, and designed with absolute safety in mind. The choice between gas and diesel is usually based on the comparative cost and the availability of the two forms of fuel.

Another type of heat source is a heat pump (also described above under COP efficiency measurement). Heat pumps are an extremely energy efficient form of space heating and
cooling. In New Zealand, most heat pumps are installed to provide heating—cooling Ins been a secondary function.

Air-to-air heat Pumps (the most common type) use refrigerant to absorb heat from one space and transfer it to another via a heat exchanger (often a in or coil). Optimum efficiency is achieved at outdoor temperatures above 6-7°C. Some models man still provide heating in temperatures as low as -15°C.