Buying guide to air conditioning

An air conditioner is basically a small version of a fridge without the insulated box. A fridge only cools the space inside it, but an air conditioner can cool a room or even a whole house.

When the unit is switched on, air is passed through the unit and over the cold evaporator coil. There it's cooled and some of the moisture that makes the air feel sticky is removed. The cooled air is blown back into the room to give you that fresh feeling.

While that's all happening, air is also used to cool the coil - this is vented through a window or wall via the exhaust hose that comes with air conditioning units. The cooling process also produces water. That's why air conditioning units have water tanks that are simply removed and emptied. Or they might have external drain facilities - these allow water to run away continuously through a thin secondary pipe.

All Homebase air conditioning units have a minimum cooling setting of 16^oC or 18^oC and a maximum setting of 32^oC or 35^oC. An internal thermostat controls the selected room temperature.

To make your air conditioning unit work efficiently, check that the hose expels the hot air to the outside and not back inside the room. Keeping the room well-sealed by closing doors and windows also ensures you get the best out of the unit. Closing blinds and curtains will reduce the heat from sunshine through windows and doors. For a cool, restful night, run the air conditioner in the day and turn off just before you go to sleep.

Adjustable thermostat

This allows you to control the temperature of the room where the unit is operating.

1-12 or 1-24 hour timer

Use the timer to select a specific operating period. After this the machine switches itself off.

Washable pre filters

Washable pre filters and odour-eating carbon filters help reduce smells. The washable ones filter the air and remove dust, dirt or hairs that could damage the machine if they get in. These filters are easy to remove and can be washed clean.

Mode settings

Some machines have three or four settings to either cool, dehumidify, fan or heat the air.

Energy efficiency

Check the rating. All air conditioners are graded from A to G for energy efficiency, with A grade the best, so saving you money.

All air conditioning units carry a British Thermal Unit (BTU) rating, which is a good guide to how much cooling a machine is capable of. The higher the BTU rating the larger the volume of air a machine can cool.

The BTU rating also gives you a good idea of running costs. A 9,000 BTU machine costs about 9p an hour to run and a 12,000 BTU machine costs 12p an hour, and so on. If you ran a 9,000 BTU machine continuously for a week it would cost around £15.

For an air conditioner to work, you have to get the heat out of the room or it can't cool it. The hose is to expel hot air, not moisture as in a tumble dryer.

Refrigerant air conditioners dehumidify - remove moisture from the air - as they cool it. This is unavoidable but can actually help allergy and asthma sufferers, as lower humidity helps prevent dust mites and other pests from breeding.

Homebase air conditioners need minimal assembly. Simply attach the flexible hot air hose outlet to the back of the unit and place the other end out of the room you're cooling - this is typically done through a window or door. Some machines come with an adapter kit that reduces the amount a window needs to be open to only about 6cm.

Plug the air conditioner into a normal 13A socket and switch on. When the unit needs emptying the full water indicator will come on. Some units have an external drain system for continuous use and you don't have to empty them.

We can bring your appliance to your home at a time that suits you - all from just £5.95.

Delivery information

To make moving your air conditioner as easy as possible, all Homebase units come with wheels and a handle for easy transport from room to room. If you need to cool both upstairs and downstairs, it may be worth buying a second unit as air conditioners can weigh as much as 35kg. That makes it a challenge to shift them up and down stairs.