Frequently Asked Questions

Which brands of air conditioning equipment do you use?

We are at liberty to choose from all manufacturers, but we mainly use the following brands: Daikin, Hitachi, Fujitsu, Mitsubishi and Toshiba.

I’ve heard many stories about Legionnaire’s disease being spread by air conditioning, is this true?

Legionnaire’s disease is caused by legionella bacterium. The bacteria can be found in any type of water system, but are most prevalent in warm (25-40°c) un-treated water.

It is usually spread when water droplets containing the bacteria are dispersed into the air, as happens with cooling towers, shower heads, spa baths etc.

It is not associated with most modern forms of air conditioning as there is no warm stagnant water involved.

How often does my air conditioning need maintenance?

This depends on the amount of use it gets. For instance, a system in a busy restaurant would probably need more maintenance than a unit in a dentists’ surgery where there are minimal levels of dust.
We would recommend as a minimum one major visit a year, if the system is in a busy restaurant or club more frequent minor visits in the interim.

How does air conditioning work?

The modern system of air conditioning/refrigeration is based upon the Rankine cycle. This relies on a specific temperature/pressure relationship of refrigerant in certain states and the high amount of latent heat needed to change the state of the refrigerant.

In the refrigeration system the gas is compressed which raises its temperature. The gas is then condensed, in the process removing the latent heat. The liquid then passes though an expansion device, which lowers the pressure and therefore temperature. The liquid evaporates, taking in latent heat. The gas is then compressed and the cycle starts again. The basic cycle was described by Carnot as early as the 1820s, but was refined by Rankine (1820-1870).

Theoretically most “air conditioning” should be referred to as “comfort cooling” as the air is only cooled or heated, with no humidity control or extensive filtration of the air.

I don’t know anything about air conditioning – can you tell me about its history?

There was rudimentary refrigeration equipment around in the 1860’s and 70’s, but this equipment wasn’t ready for mass application and production. Early installations used ammonia or sulphur dioxide as refrigerant gas. Unfortunately both of these had their problems as they were toxic or flammable at certain concentrations.

The earliest use for air conditioning, rather than refrigeration, was in the textile industry in the early 1900’s to ensure the size of cloth was not distorted by varying humidity levels.

The discovery of CFCs (chloro-flouro-carbons) was made in 1930 by scientists at Frigidaire, the then white goods section of General Motors. Along with the rotary compressor this led to the use of much smaller equipment, and through-the-window units were introduced in the 1930’s.

Japanese companies, (Daikin, Hitachi, Toshiba, Mitsubishi) introduced the first mass produced split systems in the 1970’s. This type of system where the equipment is supplied in the form of an indoor and outdoor unit, with the inter-connecting wiring and pipework supplied on site is the most commonly used type of fixed air conditioning worldwide. Since the 1980’s and the advent of electronics and computerization this equipment has become more technologically advanced and energy efficient, with Toshiba introducing the first inverter technology in 1981.

VRF and VRV systems have been in use since the late 1990’s, these are becoming the industry standard for providing heating and cooling in office blocks nowadays due to their high energy efficiency.
The exception is the USA where rooftop packaged systems and centralised chiller plant are prevalent. This is mainly due to the restriction on imports of air conditioning units, which serves to protect their own manufacturers such as Trane, Lennox, York, Carrier.