Central heating, fuelled by mains gas, oil or LPG is the most common type of heating in the UK. A boiler heats water, which is piped round the building to heat radiators. It also heats water for washing and bathing.
Boilers
If you have an old gas or oil boiler, replacing it with an A-rated condensing boiler could save you over £300 per year in energy bills according to the Energy Saving Trust. There are two main types of boilers installed in the UK:
Combi (combination) boilers are the most common. With them you don’t need a separate hot water tank or cylinder, so they are a good space-efficient option. Combi boilers take cold water directly from the mains to heat and provide hot water when it’s needed for taps and central heating. They are efficient, because their flow rate acts as a restrictor on high use, but you may have less pressure if taking hot water from more than one tap at the same time, so they are less suitable for homes where more than one–person showers at a time.
Conventional boilers (also known as regular or vented boilers) come with a hot water storage cylinder (which is typically in the airing cupboard) and a feed and expansion cistern in the loft. They are often fed by a cold-water storage tank (also in the loft). They are suitable if your home needs to get hot water from multiple taps at the same time. One downside is that if the hot water runs out, you will have to wait for it to reheat the water. Another is that your boiler may be heating up hot water that isn’t needed (which is why a well-insulated cylinder is so important.
Both types of boilers can be condensing. which is much more efficient. All new gas boilers installed since 2005 should be condensing due to a change in the Building Regulations. If you are not sure whether or not yours is, look and see if your boiler has a plastic flue. If it does, it’s probably a condensing boiler.
Underfloor heating
Underfloor heating works like having a big radiator under the floor: hot water is passed through coils under the floor, which rises to heat the room. Because underfloor heating usually operates between 35-45 degrees C, it is well suited for connecting to heat pumps, which provide lower temperature water. Because underfloor heating is a form oflow-temperature heating, it is most suitable to buildings that are well insulated and with less air exchange. It is most effective left on for extended periods rather than heating at key times, so is ideal in environments with continual occupancy.
Underfloor heating works like having a big radiator under the floor: hot water is passed through coils under the floor, which rises to heat the room. Because underfloor heating usually operates between 35-45 degrees C, it is well suited for connecting to heat pumps, which provide lower temperature water. Because underfloor heating is a form of low-temperature heating, it is most suitable to buildings that are well insulated and with less air exchange. It is most effective left on for extended periods rather than heating at key times, so is ideal in environments with continual occupancy.
Passive solar design takes advantage of the sun’s warmth and stores and releases heat back into the home in the evening. This happens to some extent in every home, as sunlight passes through windows and is absorbed by walls. But there are steps you can take in design which will increase the passive solar gain. If your home has a large glazing area facing south you will need blinds or an alternative way to reduce the amount of sunlight coming into your home as it is likely to overheat without it.
Electric heating
Individual plug-in electric space heaters are suitable for heating a space sporadically. They have high running costs compared with gas. A regular dilemma for many people is whether it’s more efficient to put on the central heating, or just heat the room you’re using with an electric space heater.
With an efficient gas boiler, radiators with temperature controls and a well-insulated or small house, it tends to be more efficient to turn on the central heating rather than just heating one room. If not, it may be more efficient to get an electric or gas heater for the room where you spend a lot of time, but be wary of creating a situation where you are moving from one very warm room to a cool one as there are health risks in doing so and you are likely to get issues with damp and mould in unheated rooms.
Water Heating
The type of water heating system most suitable for your home depends on factors including the fuel and space available and how much hot water is needed. A family with a large home and several people who need to shower at the same time has different needs than a single person living in a small flat. Typically, a home with a gas or oil boiler will be used to deliver hot water as well as space heating.
A traditional shower (or mixer shower) mixes hot water from the boiler and cold water from the tap. Electric showers take cold water and heat it on-demand. Because they heat water as it is needed and tend to have a lower flow-rate, they can be more efficient. But if you are on mains gas, an electric shower may not be as economical, because gas is much cheaper than electricity.
Immersion heaters
In a home without a boiler, water can be heated using one or more immersion heaters, often one at the top and one at the bottom of the cylinder. This applies to homes with electric storage heaters. Usually, one of the immersion heaters will switch on during the night to take advantage of cheap electricity (provided you are on the right electricity tariff) and heat the whole cylinder and the other will be used for topping up hot water as needed. Knowing how your immersion heater works and making sure that you do not leave the peak rate heater on continually will help keep your energy bills lower.
Renewable energy
You may want to consider alternative forms of heating, especially if you are off the gas grid; biomass boilers and some heat pumps can be used to heat both your space and your water. Biomass boilers are suitable for those who have space for storage of wood pellet or logs and a thermal store; heat pumps are an option in well-insulated buildings, and particularly for those currently heating with electricity.
Solar thermal panels can also be used to provide hot water to your home (typically around 50% over the year), so you will still need a back-up in the form of a boiler or immersion heater.
Visit SuperHome’s pages on renewable energy for more information on these types of technology.
