Does lowering your boiler flow temperature to 60°C really cut your gas bill?

Yes, for many homes with a condensing combi boiler, turning the flow temperature down to about 60°C can cut gas use, and it costs nothing. The evidence says up to 9% in a lab test, and the real-world saving is probably smaller. It is also not right for every home, so check the cautions below before you touch the dial.

I'll explain what the setting is, what the research found, what it might be worth in pounds at today's gas price, and who should leave it alone.

What is boiler flow temperature?

Flow temperature is how hot the water leaving your boiler is when it heads to the radiators. It is separate from the room thermostat, which only tells the boiler when to switch on and off.

According to EDF's guidance, boilers are usually set to around 75°C to 80°C at installation, which is too high for most combi boilers to run at maximum efficiency. At lower temperatures the boiler spends more time in condensing mode, where it recaptures heat that would otherwise go up the flue.

What does the evidence say?

EDF's page reports research from the Salford Energy House:

• Dropping from 80°C to 60°C cut gas use by up to 9%.
• Dropping from 80°C to 55°C cut it by up to 12%.
• Once the room reached 21°C, the room temperature was the same at 60°C, 55°C and 50°C.
• The trade-off was speed: heat-up time went from 23 to 37 minutes at 60°C.

The same page says Nesta estimates an average household could save around £65 a year, based on September 2023 energy prices, and gives a lower figure from the Energy Saving Trust of about 4% for a drop to 60°C. It also says results depend on the home.

There is a caution here. Nesta's own trial found no statistically significant difference in daily gas use for households that received a one-off email advising 60°C, compared with a control group. Advice alone did not clearly change what people did. So treat 9% as the top of the range, and 4% as a sensible planning figure.

What it might save you: a worked example

On 25 October 2026, the Flexible Octopus gas rate in London was about 8.1p per kWh including VAT, from the Octopus Energy API. Your region will be close, and your bill has your exact rate.

I've applied the 4% and 9% figures above to three sizes of home. The gas use figures are my assumptions for illustration, not measurements.

Gas used for heating in a year	Heating cost at 8.1p	Saving at 4%	Saving at 9%
6,000kWh (small flat)	about £489	about £20	about £44
10,000kWh (typical house)	about £815	about £33	about £73
14,000kWh (larger or leakier home)	about £1,140	about £46	about £103

A saving of roughly £20 to £100 for a few minutes with the manual is a fair return. It will not change your life, but it is free, and you can reverse it. EDF's page notes the setting can be changed back at any time.

Who should not do this

This is the part to read before you touch anything.

• Vulnerable households. EDF says that if anyone in your household is more vulnerable to the cold, for example an older person or someone with an underlying health condition, please don't set your flow temperature below 60°C. A hotter flow also heats the house faster.
• Homes with a hot water cylinder. EDF says you need a condensing combi boiler to change the flow temperature safely yourself. For system boilers or homes with a hot water cylinder, get a qualified professional to check first. Stored water should stay at 60°C or higher to reduce the risk of Legionella bacteria, and lowering the flow temperature on a cylinder system could let it fall too low.
• Anyone unsure. If you can't find the setting, check the boiler manual or ask a Gas Safe registered engineer. Don't force it.

How to try it

1. Confirm you have a condensing combi boiler (no hot water cylinder). If not, stop here.
2. Find the heating flow temperature setting in your manual. Where it sits varies by make and model.
3. Lower it to 60°C. EDF suggests slightly lower is possible in a well-insulated home, but finding the right level may take trial and error.
4. Live with it for a week or two. Radiators will feel slightly cooler to the touch. That is expected.
5. If the house struggles to reach the thermostat temperature, nudge it back up a few degrees.

Do not change your hot water temperature in the same go. Keep it to one change, so you know what caused any difference.

Does it stack with other fixes?

Yes, and the pattern is the same as other cheap jobs. I covered a similar sum in does turning your thermostat down by 1°C really save money. A lower flow temperature works on how efficiently the boiler makes heat. Draught-proofing and a lower thermostat setting work on how much heat you need. They add up rather than overlap.

To see what each unit of heat costs you at your own prices and compare it with electric heating, put your numbers into the Gas or electric? tool.

The short version

• Flow temperature is how hot the water leaving the boiler is, and many boilers ship set to 75°C to 80°C.
• Lowering a condensing combi boiler to about 60°C cut gas use by up to 9% in a lab test, though Nesta's own trial found no clear effect from advice alone.
• At 8.1p per kWh, a typical house using 10,000kWh might save roughly £33 to £73 a year (my illustration).
• Don't do it if anyone is vulnerable to the cold, and get an engineer to check if you have a hot water cylinder.

This week, find your boiler manual and see whether the setting is easy to reach. If it is, try 60°C and give it a fortnight.