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Save up to 8% on Your Energy Bills by Making A Simple Change to Your Boiler

Killakilowatt boiler campaign launches
(Image credit: Getty Images)

An energy-saving hack could help some homeowners save up to 8% on their heating bills, simply by lowering the flow temperature on your boiler.

Energy price rises will impact millions of homeowners from 1 April, when average bills increase by 54%, so cutting costs where possible could be vital for homeowners.

Nesta, a UK innovation charity, has launched a one-year research project which will investigate the impact of lowering flow temperatures to 54°C or lower so condensing combi boilers operate more efficiently. 

"This could reduce energy use, and bills, by 6-8% per household, without affecting the warmth of the home," Nesta says.

Nesta's project will finish in January 2023 by which time it hopes to learn how best to encourage people to turn down their boiler’s flow temperature, understand the situations in which it may not be practical, and develop an intervention to lower household emissions that can be scaled across the UK.

How Does Lowering the Flow Temperature Work?

The message to lower your boiler's temperature isn't new. In 2020, a campaign called #KillaKilowatt was launched by engineer Michael Walsh, founder of Walsh and Son Ltd, who believes making simple changes to the way our boilers work could have an important benefit.

The leading message of the campaign is simple: drop the temperature flow on your condensing combi boiler (a boiler that produces your heating and hot water) to 60°C. This refers to the temperature of the water flowing out of the boiler.

Doing this will essentially help your boiler to achieve higher efficiency. It does this because at 60°C your boiler is more readily able to condense water vapour and recover latent heat from this vapourisation, which would otherwise have been lost up the flue. 

In October 2021, a report by the Heating and Hot Water Council found that lowering flow temperatures on condensing combi boilers could save homeowners around 6-8% on their gas bill.

This should not have any comfort issues for homeowners, Walsh says, and within a few weeks you should end up making a significant saving of 5200 million kW a year if 1kW is taken from every household.

Heating engineers and plumbers who joined the campaign report that most factory-made boilers have the temperature flow set around 75°C, which means the return temperatures are too high to condense as efficiently.

Condensing modes for boilers

Most boilers out of the box have their flow set around 75 degrees, which means their return temperatures are too high to condense efficiently (Image credit: Nathan James Van Gambling)

It Can Prepare Households For Renewables

Top Tip

You should contact an engineer or a plumber to help you lower your temperature flow if you are unsure how to do it yourself

Heating accounts for 47% of all energy consumption in the UK, 55% of which is used by domestic homes, and currently over 80% of domestic heating is provided by natural gas boilers, according to National Grid.

This is why the government is targeting for 600,000 heat pumps to be installed into UK homes per year by 2028. Heat pumps are one of the most effective ways of reducing emissions from our homes, but they can be inexpensive to install. A gas boiler ban could impact boiler owners from 2035, but until then making this boiler can have significant short-term benefits. 

Nathan James Van Gambling, an engineer and host of the BetaTalk podcast who has advocated for the #KillaKilowatt campaign, says that air source heat pumps, ground source heat pumps and other renewable technology have not reached a level of affordability that would lead to the average homeowner to purchase a new system. 

“The cost of low-carbon heat pumps can be off-putting, and installation can seem invasive. But even smaller measures can start, and you can soon see a decrease in your bills. This is a first-step process. Once you’ve seen the benefits then the next step to go even further is to think about getting renewable technology.” 

In June, changes to Part L of the Building Regulations will boost the efficiency of gas systems. One of the most significant changes due to be introduced will be the requirement for lower flow temperatures of 55°C or lower, to improve efficiency and reduce carbon emissions. 

Nesta says this could help to prepare UK homes for the move to renewable heat sources like heat pumps, which operate at lower flow temperatures of between 35-45°C. 

How Else Can You Boost Your Heating Efficiency?

Van Gambling recommends the following straightforward steps to assessing how efficiently your heating system is working:

  • Review your boiler’s weather compensation - this is a communication system between your boiler and an outside temperature sensor which tells the boiler to adjust the temperature of radiators to ensure you are not wasting heat, however, not all boilers have this system
  • Balance your radiators - you can learn how to balance your radiators on a DIY basis, which helps to make sure there’s an even distribution of heated water making its way to each of the radiators in your house.

The Boiler Upgrade Scheme Launches in April

From 1 April, the Boiler Upgrade Scheme will enable homeowners to apply for vouchers to lower the cost of installing heat pumps and biomass boilers. 

The £450m policy will offer grants of £5,000 for homeowners to have air source heat pumps installed, and £6,000 for ground source heat pumps. Although only 90,000 homes are expected to benefit.

The government is expected to operate a first-come, first-served basis to those who meet the eligibility criteria.  

Jack has worked in journalism for 11 years and is the News Editor for Homebuilding & Renovating, a role he has had since 2019. He strives to break the most relevant and beneficial stories for self builders, extenders and renovators, including the latest news on the construction materials shortage and hydrogen heating. In 2021 he appeared on BBC's The World at One to discuss the government's planning reforms. 


He enjoys testing new tools and gadgets, and having bought his first home in 2013, he has renovated every room and recently finished a garden renovation.