A Ground Source Heating Unit uses energy from the ground that remains rather constant, even in colder areas in New Zealand.
This energy from the ground is transferred from the earth to the water/ glycol mix that runs through pipes that are buried under the ground. They can be buried within trenches or boreholes drilled down into the ground. This pre-heated fluid runs to and through a Heatpump Unit that exchanges the energy to the heating systems that will then be used directly for potable hot water and space heating/cooling.
A Ground Source Heatpump has pipes that can also be placed in water such as a lake or river if this is available nearby the dwelling to be built.
This Ground Source Unit and the boreholes sizing and depth is all part of the calculation that takes place as part of the Heat Retention Calculation has been carried out.
There are many types of gas boilers. They run from reticulated or LPG bottles to heat water that is then used to give both potable hot water and hot water to run through a heating system. The conventional or system boilers have to be used in conjunction with a cylinder to store the hot water in.
The Combination Boiler provides hot water for potable and also hot water for any hydronic heating requirements. The Gas Boiler size is determined by the Heat Retention Calculation and the requirements of the usage.
The Combination Boiler is designed to capture and recover the energy that is normally discharged into the atmosphere. When working at its top efficiency, the water vapour produced by the burning of gas condenses back into liquid water. The boiler uses a heat exchanger so that the incoming water cools the exhaust forcing condensation of the water vapour it contains; this has the effect of preheating the water.
Diesel boilers burn Diesel to heat the hot water that then is used for heating and potable hot water. The choice of diesel boiler usually comes down to personal choice but also the availability of fuel to the dwelling location. The diesel boiler size is determined by the Heat Retention Calculation and the type of demand that is needed.
There are now Condensing Diesel Boilers, which offer a better fuel efficiency in their usage. They have great control safety and performance features. The diesel storage tanks are usually of a twin skinned nature to ensure no diesel leaks, to capture any leaks even if there is one.