There's one dial on most combi boilers that's quietly costing households money every single day. It takes two minutes to fix, costs nothing, and your house still gets just as warm.
What is boiler flow temperature?
Flow temperature is how hot your boiler heats the water that goes round your radiators. It's not the same as your thermostat, which sets how warm you want the room.
Most combi boilers come out of the box set to 70 or 80°C, and most people never touch it again.
Why a lower setting saves money
A combi boiler is designed to work best at 60°C or below. At that temperature it goes into what's called "condensing mode", where it recovers heat from its own exhaust gases that would otherwise go straight out the flue.
Set higher, it can't do that, so it burns more gas for the same warmth. The charity Nesta, which runs the Money Saving Boiler Challenge, found that turning it down can cut gas use by around 10%.
The only difference you'll notice is that rooms take a wee bit longer to warm up.
How to turn it down
- Find the controls on the front of your boiler. Most have two dials or two sets of buttons.
- Look for the one with the radiator symbol. Leave the one with the tap symbol alone, as that's your hot water.
- Turn the radiator dial down to 60°C. If your house still feels comfortable after a few days, you can try going a bit lower.
- If you're not sure which is which, check your boiler's manual, or ask your engineer at your next service.
Combi boilers only. If you've got a hot water tank (cylinder), don't change anything without speaking to a Gas Safe engineer first, because the water in the tank needs to stay hot enough to be safe.
Turning the dial down cuts how much gas you use. The other half is paying less for the energy itself, and that's where Utility Warehouse comes in. If you've not heard of them, here's the Utility Warehouse history: 30 years from a pub chat to 1.4 million customers.
MoneySavingExpert's latest prediction is that the Energy Price Cap could rise by around 23% from 1 January 2027, on top of the 4% rise in October. Ofgem confirms the actual figure by 25 November, but wholesale gas prices are already pointing the wrong way.
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Source: MoneySavingExpert Price Cap prediction (average of EDF, British Gas and E.ON Next forecasts, updated September 2026). Figures may change when Ofgem confirms the January cap.
Common questions
Will my house still get warm?
Yes. Your thermostat still decides how warm the room gets. At a lower flow temperature the boiler just gets there a little more gently, so it takes a bit longer.
Does it affect my hot water?
No. On a combi, the radiator dial and the hot water dial are separate. You're only changing the radiator one.
What if my home feels cold at 60°C?
Nudge it back up to 65°C. In very cold snaps some homes, especially older ones with small radiators, need a bit more. Even a small reduction still saves gas.
Helping UK Families spend less on their household bills
I'm Alexander Moody, an independent Utility Warehouse Authorised Partner based in Glasgow.
I help households across the UK bring their Gas, Electricity, Broadband, Mobile & Insurance together with one trusted supplier: one bill, one provider, and usually a lower total cost.
There's no pressure and no hard sell. I'll look at what you pay now, show you honestly whether Utility Warehouse would work out cheaper, and leave the decision with you.