A simple change to boilers could save household energy, without affecting their heat
The majority of condensing boilers in the UK do not operate as efficiently as they should. They burn more gas, create more emissions and cost households more money than they need.
But households can easily improve their boiler’s efficiency by lowering its flow temperature – the temperature at which boilers heat the water that is sent to our radiators. This simple change could reduce household energy consumption by 6-8%without affecting the warmth of our homes and without the need for a visit by an engineer.
How can I lower my flow temperature?
Nesta has developed a simple tool to guide you through the flow reduction process for your type of boiler. It also includes advice on other changes you can make to your heating system to complement lower flow temperatures.
Why does it work?
Condensing boilers must be set to have a flow temperature of 55°C or less to operate in their efficient condensing mode. This efficiency will continue to increase as the flow temperature is lowered. For example, the the efficiency with a flow temperature of 50°C will be around 90% whereas at 40°C it will be closer to 95%.
When the boiler is operating in condensing mode, it can recover any heat remaining in the water after it has passed through the radiators. This means the boiler doesn’t have to work as hard or burn as much gas to heat the water again, improving its efficiency. There is also a small secondary saving as less energy is needed to heat the water to a lower temperature.
However, the vast majority of boilers are currently installed to have a flow temperature between 60 and 80°C, which prevents the boiler from even entering condensing mode. This means that most households could easily improve the performance of their boiler by adjusting the flow temperature to 55°C or lower.
Won’t my house be cooler?
While lower flow temperatures mean your radiators may not be as warm to the touch, your home temperature won’t be colder.
Lowering your boiler’s flow temperature is not about changing the temperature on the thermostat. It’s about allowing your boiler to heat your home more energy-efficiently and economically. As long as your thermostat is still set to the same target temperature, your boiler will continue to send hot water through your radiators until the thermostat detects that the room has reached the target temperature.
Cooler radiators mean your home could take a little longer to warm up, especially if your heating has been off for a few hours. This means you may need to set your heater to start a little earlier, or run longer than usual, to compensate for this. The savings from more efficient boiler operation will offset this increased heating time in almost all cases.
Why are the boilers not installed with the correct flow temperature?
There are several reasons why boilers are usually configured with higher flow temperatures. First, some installers have not been properly trained in the installation of modern high-efficiency boilers. Boiler manuals also often suggest using higher flow temperatures and many naturally use this as a guide when setting up the boiler.
However, even engineers who have the knowledge may be reluctant to do so to avoid complaints, recalls and bad reviews. This is because households, who often expect radiators to be hot, might think their boiler is not working properly if they had cooler radiators due to lower flow temperatures.
Similarly, some very poorly insulated homes may not be suitable for lower flow temperatures. Even if it’s a small number of homes, engineers can feel safer installing boilers in a uniform, but inefficient way, to ensure that the installation will provide enough heat and comfort no matter what. or the type of property. This is also why boiler manuals may suggest using high flow temperatures.
Other benefits
While the obvious benefit of lower flow temperatures is the immediate reduction in household fossil fuel use, emissions and costs, there are other benefits as well.
If UK households are more familiar with the style of heating associated with lower flow temperatures, this could prepare the country for a switch to low-carbon heat pumps, which also work with lower flow temperatures. lower. This is important because the transition from fossil fuel home heating to green electricity heat pumps will be an essential step in the decarbonization of homes over the coming decades.
Similarly, for people wishing to install a heat pump, testing low temperature heating with their boiler could give them the assurance that they would still be comfortable if their home was heated by a heat pump. It could also indicate if they need to make any modifications to their home in preparation for installing a heat pump.
Finally, using a boiler more efficiently can extend its life. Not only will this reduce resource demand and save households money, but it could also mean that many of us will be able to continue using the same boiler until it is possible to switch to an alternative. low-carbon heating. If households can avoid buying a new boiler that locks them into another 15 years of fossil fuel use, they will be better able to switch to a heat pump in the short term.
References
Heating to Net Zero: HHIC Systems Group White Paper
Heat Geek: Condensation Theory – How Condensing Boilers Improve Efficiency?