Central Heating Boilers
Soaring energy prices in the UK, and the cost of heating in particular, are raising awareness amongst home-owners of the need to make their homes more efficient to reduce energy consumption.
Central heating and hot water heating account for well over half the money a typical household spends on energy, and therefore it is essential to have an efficient heating system.
There are several different types of fuel which can be used to power central heating, and a variety of different boilers to suit.
A Typical Central Heating Boiler.
Most new boilers are condensing boilers, which are much more efficient; and building regulations now demand that condensing boilers are fitted in all new installations for most types of fuel.
If you are replacing an existing central heating boiler, you can narrow down your choices by fuel type; but if you are installing central heating into a property for the first time, you must decide on the type of system you are going to use before selecting a boiler.
Which fuel?
The most common fuel in use in the UK is gas. It is usually the cheapest fuel to use for central heating, and with the exception of wood, is the most environmentally-friendly.
If you don’t have a mains gas supply, it may be worth checking the cost of connecting it to your property; if there is a supply nearby, it may prove cheaper in the long run to pay for a connection rather than use a different fuel.
Some four million homes in the UK are not connected to mains gas, and there are several different types of fuel available for these properties. Wood chips or pellets are one of the cheapest forms of fuel, and are also very environmentally friendly.
The amount of carbon emitted by the burning of the wood is equivalent to the amount absorbed during its lifetime. If one tree is planted for every tree used for heating, wood is a sustainable form of energy.
Oil and LPG tank gas are other options which can be stored on-site and used to power the central heating. Oil is more expensive than gas, and less environmentally-friendly, however since 2007 it has been mandatory to use condensing boilers for all new oil-fired systems.
Oil condensing boilers are highly efficient, and this helps to reduce the difference in both carbon emissions and cost.
More recently, electric central heating boilers have also become available, which can run a standard wet central heating system using electricity alone. Although electric boilers are highly efficient in terms of heat production per unit of energy, electricity as a fuel is still much more expensive than other types.
Which type of boiler?
For gas systems it has been required by building regulations that a condensing boiler is used in new installations since 2005 and for oil systems since 2007.
Condensing boilers are more energy efficient than conventional boilers as they have a larger heat exchanger, and extract more heat from the burning of the fuel. As cooler gases are expelled to the flue some of them condense, and energy is also drawn from the vapour as it condenses.
Combination (combi) boilers are another alternative that can be used with most fuels and are usually the most economical. Combination boilers heat domestic hot water on demand, rather than heating it in a storage tank. As well as being more efficient, this also frees up space where the hot water tank would have stood.
Electric ‘flow’ boilers work slightly differently to gas or oil burning boilers. They heat the water in the central heating circuit directly by running it through a chamber containing a heating element. These can be used with a standard central heating system, and are more or less silent in operation.
Advice is available to help you find a dependable central heating installer.
Installing a new boiler
Choosing the right boiler for your property is very important. In the past installers would often purposely oversize a boiler to ensure there is always more than enough heat.
In practice, this actually means the boiler runs at part load, and therefore is not operating at maximum efficiency.
Speak to you installer about selecting one which is the right size for your size of property.
A condensing boiler heats your hot water by running a coil of pipe, which is connected to the central heating circuit, through a hot water cylinder.
Heating the water indirectly like this is more efficient than heating it with a combination boiler, but heat loss from the cylinder makes the combi more efficient overall.
If you have a large family that uses a lot of hot water, a condensing boiler might be best; a smaller property with fewer people may find that a combi boiler is cheaper.
It’s also worth noting that combi boilers are not currently compatible with solar power, so if you are planning to install solar at a later date a condensing boiler may be the better choice.
Finding a good installer
The energy saving trust offers an advice line which can help you find good installers in your area – 0800 512 012, while you can also check the following websites for lists of registered installers:
- www.competentperson.co.uk
- www.snipef.org
- www.centralheating.co.uk
Any contractor installing a gas or LPG central heating system must be gas safe registered, and their details can be sourced on the gas safe website:
- www.gassaferegister.co.uk
There is no official certification required to install an oil-fired central heating system, but it is advisable to use an installer who is registered to the Oil Firing Technical Association (OFTEC):
- www.oftec.co.uk
Take quotes from at least three different local companies before choosing an installer. You can verify their credentials by checking customer references; also make sure they have a local office and have been in business for several years.
Domestic Central Heating Boilers – Summary
Central heating boilers use more than half of the energy we consume in our homes. Whether you are replacing an existing boiler or installing a new one, selecting the right type of boiler for the size of your property and the lifestyle you lead, will help to achieve the maximum savings on heating bills.
