Air Conditioning – A Complete Guide

Everything You Need to Know About Air Conditioning

We are used to having air conditioning in our cars but more and more people are installing air conditioning in their homes. The concept of air conditioning has been around for centuries and the Egyptians employed a crude form of it when they hung reeds in the window openings and had water trickling down them which evaporated as the air blew through the window and cooled the room, but it would have also made the room more humid. Even the ancient Romans employed a form of air conditioning when they circulated water from the aqueducts through the walls of their homes.

An air conditioner today will make use of the same principles in that it is designed to alter the air temperature as well as the humidity of a room. This can be done either by cooling, using a simple refrigeration cycle or by evaporation, or alternatively by heating a room, depending upon its needs at the time. A system that will provide heating, ventilation and air conditioning is referred to as ‘HVAC’.

Air conditioning unit internal unit with heat and cooling function

Air conditioning unit internal unit with heat and cooling function

Refrigeration cycle

An air conditioner works by taking advantage of simple but remarkable physical law: when a liquid converts to gas (known as phase conversion), it absorbs heat. Special chemical compounds, known as refrigerants and which have the ability to change at relatively low temperatures, are forced to evaporate and condense many times over within a closed system of coils. The air conditioner moves warm air across the cold, refrigerant filled coils by means of fans and the refrigerant then absorb the heat as it changes to a gas.

The refrigerant, in its gaseous state, moves on through the system and is changed back to a liquid by putting it under pressure. This creates unwanted heat which is disposed of outdoors. The liquid cools and is sent through the system again to create an elegant cycle. Perhaps think of an air conditioner as a fridge but without the insulated box. With that in mind you will understand the need to keep windows and doors closed when using an air conditioner.

Besides carrying out the basic job of cooling the air, an air conditioner will also monitor and regulate the air temperature so that it does not make the room too cold, and it does this by means of a thermostat. And it will also function as a dehumidifier- (removing excess moisture from the Air)

Larger air conditioners work a little differently in that the system is often linked to the heating system of a house and the unit venting the heat is placed in a housing unit outside the property. In larger buildings, such as hospitals or hotels, the exterior unit is often placed on the roof.

Air conditioning celing unit

Air conditioning celing unit

Features on an air conditioner

  • Adjustable thermostat
  • Timer
  • Washable pre-filters (help to reduce smells and remove dust etc)
  • Mode settings (cool, dehumidify, fan or heat)
  • Energy efficiency (an A rating will save the most money)
  • BTU rating (the higher the rating the larger volume of air can be cooled)

There are several types of air conditioning units available depending upon your needs.

Costs mentioned c2012

Portable

Also referred to as a monoblock system, this type of unit can be moved from room to room and is the cheapest system to buy. It is simply a case of plug in and go. It’s good to remember that it will only cool small areas and may not be as efficient as a larger system and it can be expensive to run.

Cost: £80 – £150

Portable stand alone air conditioning unit bulky and unsightly

Portable stand alone air conditioning unit bulky and unsightly

Wall, ceiling or window unit

With this type of unit all of the components are fitted into one box. The unit is placed so that the cooling part of the unit is on the inside and the heat extraction part is on the outside of the building. This will only cool the room it is installed in.

Cost: start at £500 plus the cost of installation.

Air conditioning window unit more common in the USA

Air conditioning window unit more common in the USA

 

This type of unit that both heats and cools is ideal for conservatories that tend to be cold in winter and to warm in summer

This type of unit that both heats and cools is ideal for conservatories that tend to be cold in winter and to hot in summer

Split air conditioner

With a split air conditioner you will be able to cool one or two rooms in a home. The compressor is located outside. Fan units are located inside and copper refrigerant pipes are connected between the units. Having the compressor externally fitted mean these units are quieter.

Cost: A typical 1 Room installation will cost approximately £700 plus the cost of installation.

Typical air conditioning unit showing both the internal and external parts

Typical air conditioning unit showing both the internal and external parts

Multi-split air conditioner

This is a similar system to the split air conditioner, but with the ability to install more units, possibly up to four if installed with a more powerful compressor. They are typically used in commercial units. They can require more maintenance to work properly.

Cost: depending on how many rooms and the size of the compressor.

Central or fixed air conditioning unit

This unit is often installed in a purpose made room and supplies cool air through a Ducting system to each room in the building. It has the ability to be controlled remotely and can also be set to control the environments of each room separately. This system is quiet and efficient and can be the ideal solution for larger businesses. A retrofit can be very disruptive and systems are usually installed during the construction of a building.

Cost: individual quotes will be required for large systems such as these. As with all contracts, it is important to compare at least three quotes. It may also be advisable to hire the services a company who are registered with a trade association.

Ducted air conditioning tends to be used more in larger buildings

Ducted air conditioning tends to be used more in larger buildings

  • Heating & Ventilation Contractor’s Association (HVCA)
  • Air Conditioning and Refrigeration Industry Board (ACRIB)
  • Associated Air Conditioning and Refrigeration Contractors’ (ARC)