Image of a woman adjusting the settings on her boiler

Boiler flow temperature

Want to reduce your energy use by up to 9%?

All you need to do is change the boiler flow temperature on your combi gas boiler to 60ºc or below and start saving today.

What is a boiler flow temperature?

Combi boilers have a “flow temperature” – this is the boiler water temperature before it gets released to the radiators around your home. The higher your flow temperature is set, the more gas you use.

Your flow temperature may be set too high if:

You have a combi boiler that’s been fitted in the last five years
Your home heats up very quickly once you put the heating on
Your radiators get very hot to the touch

Most new combi boiler settings have the flow temperature set by default between 70ºc and 80ºc. But the most economical settings for a combi boiler is 60ºc or below. By turning the flow temperature down to 60ºc, your thermostat temperature will stay the same, it’ll just take a little longer and use less gas in the process–reducing your energy use by up to 9%*.

If you have a heat only or system boiler we don’t recommend turning your boiler’s flow temperature down yourself, as there could be a risk of legionella bacteria growing in your cylinder. Please contact a plumber or boiler engineer for advice before making any changes to your settings.

How to change your boiler flow temperature

Image of a couple preparing food in their kitchen

Save up to £112* on your annual energy bill with one simple step

Start saving today without having to turn down your heating or change the temperature of your home.

You don't need a plumber or engineer, you can adjust it yourself, with one easy change you can reduce your boiler flow temperature to 60ºc or below.

By reducing your flow temperature you'll be doing your bit to reduce your carbon emissions too.

Our friends at Nesta* have created a useful online tool to help you get started. They'll ask you questions to locate your boiler type and give you step by step instructions on how to lower your boiler flow.

If you’re unsure and don’t want to make the change yourself, please contact your local boiler engineer/plumber who’ll be able to help you.

If you have a health condition, we advise you to seek further advice before considering reducing the flow temperature of your boiler.