Heating
Central heating systems and heating controls together with secondary heating and ventilation can all contribute to our comfort and well-being but they have significant economic and environmental costs.
Central Heating Systems
To provide space heating and hot water, most homes have a central heating system or electric storage heaters with a hot water cylinder heated by an electric immersion heater.
Central heating consists of a boiler which provides hot water and heats radiators or underfloor heating pipes. A traditional (or regular) boiler, which has a feed/expansion tank in the loft, heats the water in a hot water cylinder and provides low pressure water to the radiators. A system boiler still requires a hot water cylinder but does not need a feed/expansion tank in the loft. They are economical to run and can usually be combined with solar water heating systems.
A combination or ‘combi’ boiler does not require a hot water cylinder or a feed/expansion tank in the loft. Combination boilers are usually ideal for smaller properties because they heat water directly from the mains. As there is no stored hot water, the system can be very cost-effective and energy efficient when compared with older systems.
The most popular heating fuels are: mains gas; electricity; oil; liquid petroleum gas (LPG); coal and coal-based solid fuels, and wood (biomass). Mains gas is the most popular heating fuel in the UK as it is usually the cheapest option. It is the cleanest of the fossil fuels but it does produce carbon dioxide when it is burned, so it is not an environmentally-friendly heating fuel.
Gas-fired boilers should only be installed and maintained by Gas Safe registered engineers.
For some heating installations, it is necessary to provide adequate ventilation and carbon-monoxide detectors due to the health risks associated with burning fossil fuels.
Electricity is often used to provide hot water and space heating for properties that are not on the gas network. The use of electrical immersion heaters and storage heaters can be relatively expensive, even when using the cheaper Economy 7 and 10 tariffs. Electric heat pumps are much more efficient but they generally use electricity at the standard tariff rate.
Following their successful use on the continent, infra-red panel heaters are now often being promoted in preference to individual convector heaters.
Although electricity is usually very efficient at the point of use, it has been associated with high levels of carbon emissions because of the heat that is wasted at the power stations where it is generated. However, electricity generated by renewable sources like solar PV hydroelectricity and wind farms is changing this, and companies like Good Energy claim to be a 100% renewable electricity supplier.
The Which? Guide to Home Heating Systems gives useful advice on the different fuels and heating systems.
More information on biomass and heat pumps is also provided on our website.
Biomass boilers, solar water heating and certain heat pumps may be eligible for the Government’s Domestic Renewable Heat Incentive. The money is paid through the Domestic RHI scheme.
Secondary Heating
Secondary heating (individual heaters) can be useful for heating rooms where there is no central heating – or where the central heating is insufficient or turned off. Secondary heating is usually less efficient than central heating. Stoves that burn wood or solid fuel are much more efficient than open fires. OFTEC can provide advice on self-certifying engineers who can install this type of stove – and other types of heating for properties that are not on the mains gas network.
Heating Controls
Modern heating controls can make a big difference to the amount of energy used - and the associated fuel bill. The type of heating control depends on the type of heating system, but there are five general types:
- The timer turns the boiler on or off at set times.
- The room thermostat measures the room temperature and adjusts the boiler accordingly.
- The programmer sets the operating times and temperatures for different days of the week
- The thermostatic radiator valves (TRVs) are set to adjust the temperature of individual radiators so that they are turned off when the desired temperature is reached.
- Smart thermostat control systems, such as Nest, Honeywell and Hive control the heating systems remotely. Some of the systems have been reviewed by Which?
Ventilation
Ventilation is necessary to enable fresh air to replace stale humid air and to provide air for some fuel-burning appliances. Buildings have traditionally been ventilated through windows, vents and draughts (where air is leaking through gaps in the building fabric). Adequate ventilation is vital for the health of the building’s occupants, but excessive ventilation can lead to discomfort and unnecessary heat loss which is costly in both financial and CO2 terms.
For new buildings, these issues are addressed by the Building Regulations where the emphasis is on designing buildings with controllable ventilation to improve energy efficiency. Because ventilation is required for some heat-producing appliances and it affects the thermal efficiency of a building, there are a number of approved documents relating to ventilation, but the main document is Approved Document F of the Building Regulations.
There are a number of choices for existing buildings. These include:
- a) individual extract fans for the kitchen and bathroom with trickle ventilators in other rooms;
- b) positive input ventilation systems;
- c) passive stack systems;
- d) heat recovery ventilation systems, and
- e) whole house ventilation systems with or without heat recovery.
For advanced systems, the incoming fresh air can be heated by solar panels which also heat the water in the hot water cylinder.
It is important to achieve reasonable comfort levels in the winter months but overheating in the summer months should also be considered when a new system is being proposed.
Consideration should also be given to purge (i.e. rapid) ventilation and the extraction of cooking smells. The heating, cooling and ventilation aspects of a building should be considered together, ideally with specialist help. Whichever solution is chosen, it should not be allowed to compromise the ventilation requirements of fuel-burning devices and parts of the structure like roof spaces and voids beneath suspended ground floors. In some areas, radon may also need to be considered.