With fuel prices staying higher than their historical average, it’s become increasingly important to consider boiler efficiency. But what is boiler efficiency and what determines it?
What does boiler efficiency refer to?
You may have seen advertisements for boilers claiming 90% efficiency or more, but what does this really mean? Gas, oil and LPG boilers burn their respective fuels to generate heat. Unfortunately, not all of this heat ends up heating your home, because some of it escapes through the flue. Boiler efficiency basically refers to the portion of this heat that is actually used to heat your home. For example, when a boiler is working at 90% efficiency, only 10% of the heat from combusting fuel is wasted.
Boiler efficiency is an important aspect of home heating efficiency, together with good insulation to reduce the rate at which a home loses heat. A number of factors influence how efficient a boiler is, such as its design, the technology it uses and its age and condition.
Technologies that improve the efficiency of modern boilers
The boilers of many years ago were made to different standards with lower efficiency. For example, a G-rated boiler is less than 70% efficient, meaning that about a third of energy is going straight out of the flue. Fortunately, modern boilers take advantage of technology to reduce the amount of heat lost.
One of the big changes in recent years is the introduction of condensing boilers. These achieve greater efficiency by taking the hot exhaust gases that would normally be released out of the building through the flue. These are passed instead over a heat exchanger to pre-heat water as it returns from the radiators. This in turn means that the burner has less work to do, so less gas is consumed. As hot gases pass over the heat exchanger, the water vapour cools and condenses into droplets that safely drain away through a condensate pipe.
The condensation process is dependent on the temperature of the return flow, however. Lowering the flow temperature on your boiler can improve efficiency, but with cooler radiators, your home may take a little longer to heat up. Modulation technology can also help here. Boilers used to have just one power level and simply turn on and off when needed, leading to frequent pauses in milder conditions followed by bursts of hot water. Modulation enables boilers to adapt more intelligently to a range of environmental circumstances.
When the temperature outside is higher and the home needs less heating, a modulating boiler works at a reduced power for longer periods over fewer cycles. This reduces the number of stops and starts, as well as the thermal shock involved, meaning that components are exposed to less stress and tend to last longer. The system also automatically runs at a lower temperature when it can, which helps condensing boilers to run more efficiently. This also tends to minimise noises like creaks in the system due to pipes expanding.
Age and condition
The age of a boiler can affect its efficiency in a couple of ways: First, very old boilers were built to different designs and may lack the recent technology improvements mentioned above. There’s a good case for simply replacing such boilers, because it can give a substantial efficiency boost. Parts may also not be available for older boilers, so a breakdown could mean a new boiler will be needed anyway.
Second, it’s inevitable that the components of a boiler will deteriorate over time. For example, burners may fail to achieve full combustion or heat exchangers may become coated with limescale or soot. Both these phenomena hinder the operation of the boiler, meaning more gas needs to be consumed to compensate.
Annual servicing is vital to limit this degradation and maintain a boiler’s efficiency for as long as possible. For example, a qualified engineer will typically clean the internal components and ensure complete combustion as part of a service. An annual service is also important for ensuring safety, and some reliability issues may be identified before they become a real problem, potentially preventing a breakdown in the middle of winter.
Xgas can send heating engineers to Wrexham and other nearby locations like Chester and Ellesmere Port to improve the energy efficiency of your heating system. Xgas offers pay-monthly care plans that include an annual service in addition to breakdown assistance. Financing options are also available to spread the cost of installing a modern efficient boiler should it be needed. Get in contact to learn about these and other services.