Cooling Only or Heating and Cooling? Which Air Conditioning Unit Should You Choose?

Why do some split systems heat and cool while others only cool?

Every split system uses the same basic parts: an indoor unit, an outdoor unit with a compressor, and refrigerant pipework connecting the two. A cooling only unit is built to move heat in one direction, from the room to the outside. A heating and cooling unit, often called reverse cycle, adds the components and controls needed to run that process backwards.

Cooling only models tend to appear in commercial settings such as server rooms, kitchens or shops with constant heat gains, where heating is never wanted. In homes, reverse cycle units are the norm.

How does a heat pump heat and cool the same room?

Most split air conditioners are air to air heat pumps. They move heat rather than make it. In cooling mode, refrigerant absorbs heat from the room at the indoor unit and carries it to the outdoor unit, which releases it outside. That is why the outdoor fan blows warm air on a summer day.

In heating mode, a component called a reversing valve switches the direction the refrigerant flows. The outdoor unit now absorbs heat from the outside air, and the indoor unit releases it into the room. Outdoor air still contains usable heat on a cold day, so the system can keep heating even when it feels cold outside.

Are cooling only units cheaper or more efficient?

Slightly, in some cases. Without the reversing valve and the extra controls for heating mode, a cooling only unit can cost a little less to buy and can be marginally more efficient at pure cooling. For a room that will genuinely never need heat, that can be a sensible choice.

For most homes the saving is small compared with what you give up. If you later want winter heating from the same room, a cooling only unit cannot provide it, and you would be paying to heat that room another way.

Does heating with air conditioning make sense for my Kent home?

Often, yes. Kent winters get properly cold, particularly in exposed and coastal parts of East Kent, and many people end up topping up a chilly room, extension or home office with a plug in electric heater. That is an expensive way to heat. A fan heater, oil filled radiator or convector turns electricity into heat at roughly 1:1, so one unit of electricity gives about one unit of heat.

A heat pump typically delivers around 2 to 3 units of heat for each unit of electricity, depending on the model, the outdoor temperature and how the system is set up. It is moving heat that already exists outdoors rather than generating all of it from electricity. For the same warmth in the same room, that usually means using noticeably less electricity than a plug in heater.

What that means for your bills depends on your tariff, how many hours you use it and how well the room holds heat. Our guide to air conditioning running costs and winter heating shows how to work out an estimate from your own unit rate, and how to compare heating with a heat pump against gas.

What happens on the coldest days?

A heat pump's heating output and efficiency fall as the outdoor temperature drops, because there is less heat in the outside air to collect. In freezing, damp weather the outdoor unit also runs short defrost cycles, which briefly pause heating. The exact performance depends on the model, so check the manufacturer's heating data at low outdoor temperatures if the system will be your main heat source in that room.

On the coldest few days of the year, a backup source of heat may still be useful, especially in a poorly insulated room. For most of the Kent heating season, which is mostly cool and damp rather than severely cold, a heat pump is usually the better choice for both running cost and comfort.

Which type should I choose?

• Choose heating and cooling if the room is used year round, if you currently use a plug in heater there, or if you would like the option of winter heating later. Bedrooms, living rooms, extensions, garden rooms and home offices usually fall into this group.
• Consider cooling only if the space produces heat all year and will never need warming, such as some equipment rooms or busy commercial kitchens, and the upfront saving matters to you.
• If heating is a priority, size the system for winter heat loss as well as summer cooling. A unit chosen only for summer may struggle to warm the room on a cold evening. Our sizing guide explains what affects the right capacity.

The systems we quote for homes are air to air heat pumps, so they heat as well as cool. Our home air conditioning page covers the rooms they suit best and what to expect from installation.

Frequently asked questions

Can a heat pump air conditioner replace my central heating?

For a single room or a few rooms it can provide the main heating, but whole home replacement needs a proper heat loss assessment. Ordinary split systems also do not heat tap or shower water, so a boiler or another hot water source would still be needed.

Is a reverse cycle unit noisier when heating?

Not as a rule. Sound depends on the model and fan speed. In cold weather you may hear the outdoor unit change sound during a defrost cycle, which is normal.

Can I add heating to a cooling only unit later?

No. Heating relies on components built into the unit, so you would need a reverse cycle system instead. It is worth deciding before installation.

Get an estimated price for your room

If you would like heating and cooling for a room in your Kent home or business, get an estimated installed price online. Answer a few questions about the room and property, and your final price is confirmed after an installation check. For more background, the Energy Saving Trust explains air to air heat pumps.