1. Introduce the concept

What's required?

Explain what flow temperatures are, how they relate to heating the home and why there may be efficiency savings to be made. To professionals, this can seem straightforward but users generally have low awareness of flow temperatures.

When offering advice you should start by:

  • concisely explaining the technical reason for lowering the flow temperature
  • explaining the financial and environmental benefits
  • reassuring users that their comfort will not be affected.

You may wish to emphasise these differently depending on the audience.

Why do it?

Nesta’s work has found that households often receive conflicting advice on the best and most cost-effective way to heat their home, and often lack the confidence to make changes themselves. The advice to lower boiler flow temperatures can seem counterintuitive, so it is important that they are told it will not lead to lower home temperatures overall.

By being transparent about the reasons behind this action we can build more confidence in making the change. Doing this early on in the process also builds users’ confidence in changing wider heating habits. This will ultimately help users to understand that comfort isn’t affected as a result of lowering flow temperatures.

How to do it

Key points and assets to help build your service.

  • Help people to understand why boilers aren’t running efficiently

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    It’s important to emphasise that combi boilers can be made to run more efficiently and that this could save gas.

    Key points to consider:

    • Combi boilers reach the highest levels of efficiency when the water that heats the radiators returns to the boiler below 55 degrees.
    • Most boilers in the UK are set at temperatures above this, with the average temperature of water to radiators being around 70 degrees.
    • When a combi boiler’s flow temperature is set to 60 degrees it will be condensing. This allows for the boilers to run more efficiently and burn less gas.

    Useful resources

    • Make it clear what is meant by flow temperature

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      Boiler flow temperature isn’t widely understood. Outline what it is and what role it plays in heating the home.

      Key points to consider:

      • Boiler flow temperature is the temperature of the water that is sent to radiators by the boiler.
      • The water is heated by the boiler using gas and, as it travels around the system through the radiators and back to the boiler, it cools down.
      • It does not affect the water coming from the taps or showers.
      • It is separate from the temperature shown on the thermostat, which is the air temperature in a room, not the temperature of the radiators.
      • Combi boilers are only condensing and begin to reach optimum efficiency when the water that has gone through the radiators and is returning to the boiler is 55 degrees or less.

    • Illustrate the potential savings and benefits

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      Different users might be motivated to turn down their flow temperatures for different reasons, so it might be useful to stress different benefits depending on your audience.

      Key points to consider:

      • Changing settings on combi boilers could reduce the amount of energy used to heat homes.
      • By reducing the flow temperature, users could save up to 9% on their gas bill.
      • This equates to a saving of around £112 a year in energy bills for a typical household.
      • If 10 million UK homes reset the boiler flow temperature to 60 degrees or below, those households would cut £1 billion from their energy bills and save 1.7m tonnes of carbon emissions; the equivalent of almost 6 million transatlantic flights.

    • Reassure that comfort won’t be affected

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      Users are understandably concerned about making changes that may affect their household comfort or health.

      Key points to consider:

      • Lowering the boiler flow temperature won’t necessarily lead to lowering the temperature of the house.
      • There may be a need to tweak other settings in the home to ensure comfort is maintained.
      • These changes could lead to the boiler running for slightly longer than before, but it should still save money overall N.B. further guidance on this is provided in step 4, provide wider heating advice.

    • Explain that it’s quick and easy to do

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      Households may have reservations about changing settings on their boiler. It can often be seen as a complex technology that should only be operated by trained professionals.

      Key points to consider:

      • Changing the boiler settings is something that can be done by anyone, including householders. It is recommended by boiler manufacturers and energy companies.
      • It is a quick change that should take no more than a few minutes.
      • Users may have to tweak the settings further to find the right balance between heat and energy/money saving.
      • The changes are not permanent, and they can very easily be reverted to a higher temperature or back to the original settings.
      • Settings can be changed during the year if necessary, for example, by turning the flow temperatures up during the coldest periods. Remind users to reduce the flow temperature again afterwards.