Turn down your boiler flow temperature

Adjust your boiler's flow temperature to save money and cut waste, without needing any tools or drilling.

BF-01Find your boiler manual and check the boiler typeLook up your boiler model online or find the paper manual if you kept it. Most UK homes have a combi boiler, which heats water on demand. Some older homes have a system or regular boiler with a separate hot water cylinder. The steps to change flow temperature are similar, but the menu names differ between brands, so knowing your exact model saves guesswork.

BF-02Locate the flow temperature controlOpen the boiler's front panel or control display. Look for a dial or menu labelled 'CH' or 'heating flow temperature' — it is usually separate from the hot water temperature dial. On combi boilers this is often a simple rotary dial marked with a radiator symbol. On smart thermostats, the flow temperature setting is usually in an installer or advanced menu.

BF-03Write down the current setting before you change anythingNote the existing flow temperature number, or the dial position, on a scrap of paper or your phone. This lets you put it back exactly as it was if the new setting doesn't suit your home. Most combi boilers arrive from the factory set around 70-80°C for heating, which is higher than most homes need.

1 each · Notepad and pen

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BF-04Turn down the central heating flow temperatureReduce the CH flow temperature to around 55-60°C if you have a combi boiler, or lower still (down to 50°C) if your radiators are large enough to still heat the room. Turn the dial or adjust the menu setting in small steps rather than all at once. A lower flow temperature makes a condensing boiler run more efficiently, which can lower your gas bill.

BF-05Check the hot water temperature setting stays separateConfirm the hot water (DHW) temperature is still set to around 55-60°C or higher, separate from the heating flow temperature you just changed. This keeps your hot water genuinely hot at the tap and helps stop bacteria building up in the system. Don't turn hot water down as far as you turned the heating flow down.

BF-06Test the heating and check every room warms upTurn the heating on and let it run for at least an hour. Walk round the house and check each radiator gets warm and each room reaches a comfortable temperature within a reasonable time. If a room with a small radiator stays cold, that radiator may need to run at a slightly higher flow temperature, or it may need a bigger radiator eventually.

BF-07Fine-tune over the next few daysLive with the new setting for two or three days before deciding it's too low. Boilers that run at a lower flow temperature take slightly longer to heat a room, so give the system time rather than judging it after ten minutes. Nudge the temperature up a few degrees at a time if any room isn't reaching a comfortable heat.

BF-08Know when to call a Gas Safe registered engineer insteadThe flow temperature dial or menu on the boiler's control panel is designed for the homeowner to use, so adjusting it yourself is fine. Never open the boiler casing or touch any part of the gas or flue components yourself. By law, any work on the gas parts of a boiler must be carried out by a Gas Safe registered engineer.

RULES

KNOW THE RULES

The Gas Safety (Installation and Use) Regulations require anyone working on gas appliances or gas pipework in the UK to be Gas Safe registered. This does not apply to adjusting the boiler's user-facing controls, only to internal gas or flue work.

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