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Heating and hot water

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Understanding your system

In a typical UK household, more than half the money spent on fuel bills goes towards providing heating and hot water. As fuel costs rise, having an efficient and cost effective heating system is vital, and it’s one of the main steps you can take to reducing your carbon dioxide emissions.

It’s important to understand your current heating system. Nearly all homes in the UK have either a central heating system – a boiler and radiators - or they use electric storage heaters. Some homes will also make use of individual heaters that are not part of the main central heating system. 

What is central heating?

This is the most common form of heating in the UK. A single boiler heats up water that is pumped through pipes to radiators throughout the house as well as providing hot water to the kitchen and bathroom taps.

Most boilers run on mains gas, but in areas where mains gas is not available, the boiler can run on oil, LPG (tank gas), coal or wood. Mains gas is usually the cheapest, and it has the lowest carbon dioxide emissions, apart from wood. Some boilers also have an electric immersion heater as a back-up.

If you have a central heating system, you may consider these energy-saving improvements:

  • Replace your boiler with a newer, more efficient model.
  • Fit better controls and use them to make sure your boiler only provides heat where and when you want it.
  • Switch to a cheaper or lower carbon fuel or technology. Find out about renewable technologies for generating electricity and heat.
  • Make any insulation and draught-proofing improvements that you can. 
  • Use chemical inhibitors to help maintain central heating system efficiency.

What type of boiler do I have?

Since 2005 virtually all gas boilers that have been fitted in the UK are more efficient, condensing boilers. Condensing boilers have bigger heat exchangers that recover more heat from the burning gas, making them more efficient. Your boiler will be a condensing boiler if the following points are true:

  • The flue is made of plastic. If it is made of metal it’s unlikely to be a condensing boiler.
  • The boiler has a plastic pipe coming out of the bottom, through the wall and into a drain.
  • It was installed after 2005 (if it’s a gas boiler).
  • It was installed after 2007 (if it’s an oil boiler).

Combi or regular boiler?

Combi boilers

A combi (or combination) boiler provides hot water directly, whenever it is required, and does not need a hot water cylinder. Gas, oil and LPG boilers may be combination.

Regular boilers

A regular boiler provides hot water when the programmer tells it to, and then stores it in a hot water cylinder until it is needed.

A regular boiler is more efficient than a combi at producing hot water, but some heat is inevitably lost from the hot water cylinder, so a combi may be more efficient overall.

What is electric heating? 

Most UK homes that don’t have a boiler and radiators have electric storage heaters. These heat up overnight using cheaper off-peak electricity, and give out the heat during the day. If you have storage heaters, you will probably have a hot water cylinder heated by one or two immersion heaters.

Electric storage heating is more common in flats, rented property, and in homes with no mains gas connection. It is one of the most expensive heating options in the UK, and it emits more carbon dioxide than most systems although in the future there are plans to de-carbonise the national grid reducing future electricity carbon dioxide emissions. It is also harder to control electric storage heaters than radiators, especially with older systems.

If you have a system like this, you may consider these energy saving improvements:

  • Install new, more controllable storage heaters.
  • Fit thermostats and controls to make your existing system more efficient.
  • Consider making insulation and draught-proofing improvements.
  • Replace your system with an efficient boiler system.

What is secondary heating?

Many households use individual heaters, such as portable electric heaters or fixed gas fires, in addition to their central heating. This is called 'secondary heating'. Modern central heating systems are usually more efficient than individual heaters, but it can make sense to use an individual heater to heat one space for a limited time. This can help avoid over heating spaces that do not need to be heated, or are used infrequently. Secondary heating is typically provided by one or more of the following:

  • Portable electric heaters such as oil filled, convection, panel or fan heaters
  • Portable gas heaters that run on bottled gas or paraffin
  • Portable halogen heaters
  • Wood burning or solid fuel stoves
  • Open fires
  • Range cookers
  • Traditional gas fires
  • Wall-mounted gas heaters

Smaller portable heaters, such as fan and halogen heaters, can be useful if only a small room or area needs heating for a short period of time. 

Where central heating does not heat the room enough, or there is no central heating in the room, electric convection, oil-filled or panel heaters might be a suitable option for providing the required level of heat. Electric heating is 100% efficient but electricity is expensive and carbon-intensive. If you do use an electric heater make sure it is only on when it is needed.

Wood or other solid fuel burning stoves can provide adequate heating for a single room and are much more efficient than open fires and less carbon intensive. 

Open fires often provide a nice atmosphere to a room but they are very inefficient. Most of the heat from open fires goes up the chimney rather than heating your room. When your fire is not being used it will most likely be a source of draughts in your home, so make sure you know how to draught proof it. 

Portable gas heaters run on butane (bottled gas) or paraffin (heating oil). These types of heaters require good ventilation as they release combustion gasses and water vapour that can build up in unventilated rooms potentially making damp problems worse. 

Non-standard heating systems

Radiators or storage heaters provide heating in the vast majority of houses in the UK. However, a number of alternative technologies can be used, or in addition to, including underfloor heating, solid fuel stoves, range cookers, open fires, electric fires and gas fires.

Finding an installer

If you want to get a wood burning stove, the installation must comply with Building Regulations. HETAS is a Government-recognised body which approves biomass appliances and services. You can use the HETAS register to find a trained installer.

If you are installing or replacing a fixed (wall-mounted or otherwise) gas heater than you will need to use a Gas Safe Register installer

Portable heaters can be bought from DIY or home furnishing shops and do not need to be installed by a professional. You can just take them home and use them when you need them.

More information

Financial support

Find out more about grants and support and what's available in England, Scotland, Wales and Northern Ireland.

Read our guide

Take control of your heating

Read our blog for tips on making the most of your heating systems.

Read our blog

Based in Scotland?

Find out more about schemes available to help you heat your home.

Home Energy Scotland