Cooling and heating in an air conditioning system is accomplished by circulating a refrigerant with a compressor. This is the basic working principle, whether we use a typical electric heat pump (EHP) or a gas heat pump (GHP). The difference lies in the point of whether we use an electric motor or a gas engine to drive the compressor in the outdoor unit, which is called the heart of the air conditioning system.

The nature of matter is such that when a liquid is turned into gas, it absorbs heat from its surroundings and conversely when a gas is concentrated and turned into a liquid, it generates heat. Using this characteristic, we use a compressor to circulate a refrigerant, running it repeatedly through gasification and liquefaction cycles.

The natural gas heat pump is the newest, most technologically advanced heating and cooling equipment available for homes today, with an easy-to-use, fully- programmable. It delivers superior comfort, the highest efficiency and the lowest operating cost of any installation for heating and cooling system currently on the market. In addition, engine heat is recovered to increase comfort and efficiency.

Introduced in Japan in 1987, using the normal car engine as the main components. Instead of its usual function, this engine will only drive the air conditioning compressors, coupled to it.

For the Rinnai GHP, it is powered by a Toyota Camry 2.0 litre engine. This engine will drive 4 compressors, which rated 5hp each.

Therefore, at full load, this unit is capable to produce 20hp of cooling capacity. From one up to four compressors units are operated according to the air conditioning load. With this feature, the engine Revolution Per Minutes (RPM) will slowly turn to a slower RPM and therefore, the gas consumption will also be reduced.

Comparing with the conventional electrical heat pump, the condenser cooling fan is running at fixed speed whilst the GHP condenser cooling fan will only operate based on the amount of heat to be rejected. With this feature, power consumption also will be less and increased the overall efficiency of this system.

This unit can be connected to maximum 16 connections of Indoor Units, such as the Ceiling Cassette and Fan Coil Unit type. With its Individual and Central Unit user friendly control panel, user can choose to cooled the whole floor, or only sections of it. With this, there will be no need for cooling at unwanted area or space and reduced energy used.

Since the cooling system is the largest single consumers of energy in building, this unit (20 hp) consumes only 1.8 kW of power at full load. Compared to normal EHP (20 hp), that consumes 15 kW of power, in which by using the GHP will reduce the maximum demand of the electrical load.

Fast response is another advantage of this system. By a push of a button, we can operate it and the cooling requirement will be achieved almost instantaneously. At full load, the maximum engine RPM is 2700 and with a good sound proof insulation, the GHP unit is only emits 58 dB.

As a summary, with this GHP unit, significant energy saving, financial and environmental benefits can be achieved. Maintenance cost is low with extended maintenance interval of 5 years or 10,000 hours of operation.