Choosing your New Air Conditioning or Comfort Cooling Heat Pump System

How does it work?

A fridge or freezer is an appliance which removes heat from one area (where the food products are stored) and discharges this unwanted heat to another area (usually into the surrounding air at the back of the appliance).

The “refrigeration circuit” consists of a freezer section which has very cold refrigerant gas passing through it, a compressor (that’s the big black metal thing near the floor at the back) which drives the refrigerant through the pipes, and a condenser (a series of tubes at the back, which are quite warm to touch. The condenser tubes are actually discharging unwanted heat into the surrounding air. So heat transfer is occurring from inside the fridge or freeze out in to the room.

An air conditioning system works on the same principle and in fact effectively a larger version of the fridge/freezer, which removes heat from one area (a room inside the building) and discharges it through its condenser to outside the building into the ambient air. This heat transfer in operation with heat being moved from inside the room to outside through the refrigerant gas cycling around the sealed refrigerant circuit between the indoor fan coil unit and the outdoor condenser unit.

The heat pump systems operate on a reverse cycle principle. When the air conditioning system is running in cooling mode, it uses the refrigeration cycle to transfer heat from the indoor unit, through the refrigeration pipe work circuit, using a refrigerant gas such as R407c or R410a as a medium and effectively dumps the heat outside into the ambient, air using the outdoor unit heat exchanger. In heat pump mode this cycle effectively reverses & it can absorb heat from the ambient atmosphere & distribute it inside a building using the indoor fan coil units. Effectively when the air conditioning systems is set in heating mode, the indoor unit becomes the outdoor unit and the outdoor unit becomes the indoor unit during the heat pump heating operation.

In order to make it practical to install an air conditioning system in a building, the “refrigerant circuit of an air conditioner is divided into two parts,The INDOOR fan coil unit (wall mounted / ceiling mounted / floor mounted) which is similar to a fan heater with cooling tubes (the evaporator) which is the indoor heat exchanger with a fan behind it. It also has switches, thermostat, fan adjustment and on / off.

The Condenser Unit (outdoor unit) which is a box with another heat exchanger with a fan behind it, to disperse the heat carried from the inside heat exchanger through the refrigerant gas. It also has a large compressor to continuously pump the refrigerant gas around the sealed system. If it is a heat pump system there will also be a 3 way reversing valve, which switches the operation of the systems between cooling and heating, depending on what mode and temperature setting the system has been set to by the end user / operator.

The indoor units come in all shapes and sizes, some designed to fit on a wall, there are floor mounted ones or ceiling ones, with options to have them mounted into a ceiling or below a ceiling, ceiling mounted, some are hidden above a ceiling with air ducts connected, some half/in/half out of the ceiling

Heat Pumps

The indoor unit and the outdoor unit (which includes the compressor), are powered by electricity. As a guide, an air conditioner which has a cooling performance of 7KW, will consume about 2KW of electricity, when operating continuously

A heat pump system, like an air conditioning system, has an indoor unit/interconnecting pipes/outdoor unit, but it also has a reversing valve which pumps the refrigerant the other way around the circuit. This “reverse cycle” operation makes the outdoor unit cool the surrounding air, and the indoor unit discharge its heat into the room. Whilst this may appear very elaborate, there are two very good reasons for having the heat pump option:

Most rooms which require cooling, may also require heating.

A heat pump system capable of providing 7KW of heating in the room, consumes only 2KW of electricity – very cost effective on running costs. This means it is 2/7, or 28% of the running costs of an electric heater (this varies according to type of system and manufacturer).

Operation & Controls

When the air conditioner is turned on, the thermostat which is fitted to the indoor unit will determine the temperature of the room. If the room is too hot, the compressor will be started, and the “refrigerant circuit” will produce cooling within the room. When the room temperature is at the desired level, the thermostat will be satisfied, and turn off the compressor.

If the system is also a heat pump, it will automatically control the heating process in a similar manner.

Most systems which are manufactured provide heating as well as cooling, because the price difference of a cooling only system is minimal.

The above description of the workings of an air conditioning & heat pump system is very basic.

For a better descriptions of the types of units, how they can be installed, and the types of controls, can be viewed on our website You can also call us and request sales / product brochures on 024 7632 0300 (Coventry office) / 0121 695 9418 (Birmingham office) / 01604 269540 (Northampton office).

We can offer advice to our customers on air conditioning systems which can be made all over the world, main brands such as Daikin, Mitsubishi, Hitachi, Toshiba, Samsung, Fujitsu, Panasonic usually cater for the regions that they supply to and adjust their design parameters to ensure that the system they have provided will be as efficient as possible when it is working in a particular region round the world. Some less well known brands do not offer this service and design systems on a nominal basis and this means that one fits all and these will not be as efficient and can be problematic in extreme summer & winter conditions.

It is important to choose a good brand and the right type of system to meet your requirement, which should be designed and selected correctly. Chillaire offers a free no obligation, survey & design quotation service.

Air Conditioning systems will go wrong if they are not installed correctly. Chillaire has certified / qualified, design / sales engineers and technical engineer’s with the highest standards of installation quality.

Make sure the installer, whether it is Chillaire or any other can provide references, and has a good reputation.

It is imperative the installer uses ‘refrigeration quality’ copper pipes for connecting the indoor and outdoor units. The pipes must be kept free of moisture, and dirt. The pipes must be properly evacuated, using a vacuum pump, before the service valves in the units are opened.

The pipes must be jointed using proper tools, and if they are required to have brazed joints, the joints pressure tested on completion with dry nitrogen.

Refrigerant gas is usually required to be added to the system, which is from a pressurised cylinder. The new ozone friendly refrigerants require careful handing, and the additional amount of refrigerant must be calculated accurately, and weighed in to the system using electronic scales.

The system should be commissioned and tested properly by a qualified / experienced engineer.

Air Conditioning - Heating - Ventilation