Energy saving boiler challenge: Here’s how it can save you money

Boiler technician working in home.
The energy saving boiler challenge is about making a simple tweak to your boiler to lower the cost of your energy bills (Image credit: Getty Images)

An energy saving boiler challenge is encouraging households to make a simple boiler change this winter and save 9% on your gas bill. 

Nesta, a UK innovation charity, has set up the challenge to help the millions of households in the UK that own combi boilers. The challenge involves lowering your boiler’s flow temperature to ensure it is working efficiently. 

A typical annual household bill is now £2,500 following the government’s Energy Price Guarantee kicking in this month, amid soaring energy price rises, and this is one of many energy saving tips that could have an impact on your energy bills.

Here’s how to get involved in the challenge and learn why lowering your boiler’s flow temperature could have such a big impact. 

What is the energy saving boiler challenge?

How the challenge works

Learn more about Nesta’s Money Saving Boiler Challenge by clicking ‘turn down your boiler today’ on their page. You will need to own a combi boiler in order to lower the flow temperature.

Temperatures are dropping and while the risk of blackouts remains unlikely according to National Grid, the electricity system operator for the UK has confirmed it is preparing for possible energy shortages this winter. 

To help households use less energy than they need to, Nesta is advocating combi boiler owners to lower the flow temperature to 60°C to ensure their boiler runs as efficiently as possible.  

“The average household could currently save around £112 per year on their heating bill by lowering their boiler flow temperature. But many people aren’t aware they can change their boiler settings,” Nesta says.  

Nesta, which is in partnership with energy suppliers such as EDF, Octopus Energy, E.ON Next and Energy UK, claims that if 10 million households with a combi boiler lower their flow temperature to 60°C then this will cut £1bn from UK energy bills and save 1.7 million tonnes of carbon. 

Earlier this year Nesta launched a one-year research project investigating the impact of lowering flow temperatures to 54°C or lower, which will conclude in January 2023.

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)

How does lowering the flow temperature work?

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

The message of the campaign was 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 to your radiators. 

Heating engineers and plumbers who joined the campaign reported 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.

Combi boilers work best when their flow temperature is set to 60°C, Nesta says, because they are more readily able to condense water vapour and recover latent heat from this vapourisation, which would otherwise have been lost up the flue. This should not have any comfort issues for homeowners, either. 

David Stanley, Technical Operations Manager at Intergas Boilers, says: “You should set the flow temperature according to the system design; ideally you need the system return temperature to be lower than the flue gas temperature dew point.

Combi Boiler your ultimate guide

Combi boilers work best when their flow temperature is set to 60°C, Nesta says (Image credit: Getty Images)

“By setting the flow temperature too high you reduce the chances of the return water being lower than the dew point. It’s preferable to set the flow temperature as low as possible without compromising the comfort level within the property.”

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.

How to lower a boiler's flow temperature yourself

You will need to own a combi boiler in order to lower the flow temperature, and it is not recommended to reduce your boiler flow temperature if you have a water tank.

You can follow Nesta’s step-by-step guide on its Money Saving Boiler Challenge page to do this yourself. Alternatively you can check your boiler manual to learn how to correctly change the flow temperature. 

If you are at all unsure, don't just twist any knobs on your boiler, contact an engineer or a plumber or someone who does know a bit about boilers to help locate the right knob or button

How else can you boost your heating efficiency?

Nathan James Van Gambling, an engineer and host of the BetaTalk podcast who has advocated for the #KillaKilowatt campaign, 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.
Jack Woodfield
News Editor

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.