Set the heating clock back before Sunday 25 October

This page is the clock on the programmer, the room thermostat or the dial beside the boiler. It is the job for the fortnight before the change, and for Sunday breakfast after it. A boiler that will not light at all belongs on the will-not-fire page. The first overnight fire of the autumn, the pressure and the radiators belong on the heating-on page. The radiator dial on the boiler case belongs on the flow-temperature page. A carbon monoxide alarm belongs on the alarm page. If that alarm is already sounding, leave the house. Twisting a heating clock does not clear gas.

England, Scotland, Wales and Northern Ireland change together. The Royal Observatory Greenwich gives the same moment: 2am on Sunday 25 October 2026. Your phone will move on its own. The white plastic pipe outside the boiler, the garden tap and the oil tank do not care what the programmer thinks the hour is. Those checks stay on their own pages.

When the clocks move, and which way

GOV.UK’s page “When do the clocks change?”, last updated on 24 November 2025, states the rule in one sentence: in the UK the clocks go forward one hour at 1am on the last Sunday in March, and back one hour at 2am on the last Sunday in October. Its table gives 2026 as 29 March forward and 25 October back. The hour ahead of Greenwich Mean Time is British Summer Time. When the clocks go back, the UK is on Greenwich Mean Time.

At 2am British Summer Time on that Sunday, the civil clock returns to 1am. A programmer that does not follow is then one hour ahead of the phone. A programme stored as “on at 06:30” still fires when the programmer reads 06:30. The phone, now on Greenwich Mean Time, reads 05:30. The same shift hits the off time. A slot stored as 06:30 to 08:30 runs, on the phone, from 05:30 to 07:30. An evening slot stored as 16:00 to 21:30 runs from 15:00 to 20:30. The house heats earlier than the times you remember, and it also stops earlier.

That is the October direction. The cold-house story people repeat belongs to March, when the clocks go forward and a stuck programmer fires an hour late. Copying the March fix in October sends the heating the wrong way. You want the display to equal the phone after 2am on 25 October. If the display is later than the phone, you have moved it too far, or an automatic setting has already moved it and you have moved it again.

Hot water on a twin-channel programmer uses that same clock. A cylinder slot stored for 06:00 programmer time starts at 05:00 on the phone until you correct it. Fix the clock once. Leave the stored on and off times where you wanted them in real life. Rewriting the schedule to “make up for” a wrong clock, and then correcting the clock as well, shifts the house by two hours.

Which control you actually have

The badge on the wall decides the job. The boiler brand often does not. A Worcester boiler can wear a Drayton programmer. A heat pump with a weekly schedule is the same sort of clock; the heat-pump survey page is a different visit. An oil boiler’s programmer is still a clock. Changing the displayed hour is a homeowner check. Opening the case, moving a receiver or wiring a new programmer is work for someone qualified on that fuel. The Gas Safe note says when the register applies to gas work. It does not apply to reading a time.

Worcester’s Comfort I path, on that clock page, is the one to follow if that badge is on the wall. Hold the menu button for three seconds, turn the knob to settings (the spanner), enter, then time and date. Check the day, month and year. Turn the knob until DST shows, and leave ON selected if you want the automatic change. Comfort II and Comfort+ II use a menu hold of more than three seconds, then Settings and Time/date, and the same DST choice. Those steps set the permission to change. They are not a second clock you then wind backwards on Saturday.

A dial on an immersion heater is a second clock, often in the airing cupboard. If the cylinder is heated by the boiler programmer, leave the immersion dial. If the immersion is what heats the water, give that dial the same Sunday comparison. The electricity meter’s off-peak clock belongs to the supplier. Leave the meter sealed. A wrong heating hour is not a reason to open the meter cupboard.

What an hour early does to the house

Use one morning and one evening you already live with. Suppose the stored programme is heating from 06:30 to 08:30 and from 16:30 to 22:00, and the programmer is still on summer time after the change.

• The phone says 05:30 when the programmer says 06:30. The heating starts while you are still asleep.
• The phone says 07:30 when the programmer says 08:30. The heating stops. If you are still in the kitchen at 08:00 phone time, the radiators are already on the way down.
• The phone says 15:30 when the programmer says 16:30. The evening slot starts before you are home.
• The phone says 21:00 when the programmer says 22:00. The house starts to cool an hour before the evening you planned.

The waste is the early hour, not a mystery fault in the boiler. You pay to heat an empty stretch at the start of each slot, and you sit in a cooling room at the end. Turning the flow temperature up to “get the heat back” fights a different page. The flow dial does not move the clock. Bleeding a radiator because one evening felt short fights the bleed page, which is for a room that stays cold while the others heat. If every room follows the shifted times together, the clock is the common cause.

People in the groups named on the NHS page Keep warm, keep well feel that early off-time first: anyone aged 65 and over, babies and children under 5, people with a long-term health condition, pregnant women, and anyone who cannot heat the rooms they use. For those households, Sunday morning is the deadline, not the following weekend. A plug-in heater can cover one room while you correct the clock. Its limits are on the heater page.

What to do before Sunday

Saturday 24 October is still British Summer Time until 2am. A display that matches your phone on Saturday is a correct display. The useful work before bed is identification, not a new time.

1. Stand at the programmer with your phone. If the two times match, the clock is set for today. Photograph the badge and the screen, including any DST, DLS, BST or AUTO mark.
2. If the handbook or the on-screen line offers daylight saving, set that line to on, and check the date is 2026 and the month is October. Stop there if the hour already matches the phone.
3. If the control is a mechanical dial, leave it on Saturday. You will turn it on Sunday, when the phone has already gone back.
4. Read the heating and hot-water mode. Auto, Once, Twice, On and Off are programme choices. Changing Auto to On holds the heating without fixing the hour. Put the mode back if you only meant to inspect it.
5. Write down the morning and evening slots you actually want on Greenwich Mean Time. You will compare Sunday’s behaviour with that note, not with a guess.

You do not need to be awake at 2am. The extra hour is the one the civil clock inserts. A manual programmer will be an hour ahead from that moment until you correct it, which for a typical overnight off period means the error shows up at the first morning slot. Breakfast is soon enough, unless someone needs the rooms held to a strict hour through the night. In that case, correct a mechanical dial when you are up for the night, and only after the phone itself has gone back.

Sunday morning: match the display to the phone

Do this in daylight, with the phone’s automatic time zone left on. Aeroplane mode can freeze a phone on the old hour. Use a second phone if you are unsure, or the time on GOV.UK after you refresh the page.

1. Read the phone, then the programmer. If they show the same hour and minute, within a minute or two, the control has moved or it was already right. Leave it.
2. If the programmer is one hour ahead of the phone, set the programmer back by that hour so the two agree. On a dial, turn it until the time mark equals the phone. On a digital set, change the hour only, using the maker’s clock-set steps, and leave the on/off programme as it was.
3. If the programmer is one hour behind the phone, you have already corrected a control that was going to correct itself, or DST fired and someone also wound it back. Set it forward until it matches the phone, and leave DST on so March does not repeat the miss.
4. Look at the hot-water channel. It should now share the corrected clock. Do not give it a different hour to “compensate”.
5. Through the rest of Sunday, watch one on-time and one off-time against your written slots. If they match the phone, the job is finished.

A display that jumps back to midnight, or to 12:00 flashing, after you set it has lost its backup. Set it once more so Sunday is habitable. If the same blank or reset is there on Monday, the controller battery or the supply to the clock is the fault. That is a phone call, not a third attempt at the menu. If the handbook shows a battery tray on the controller you can open without tools, fit the same type the tray shows. If the clock lives inside the boiler case, stop at the case.

When the clock is not the fault

Stop the clock sequence when the display already matches the phone and the house is still wrong. Another hour on the dial will not finish these.

• You smell gas, or the carbon monoxide alarm sounds. Leave, avoid switches, and use the emergency line. In England, Scotland and Wales that is the Gas Emergency Service on 0800 111 999. In Northern Ireland, nidirect and the Utility Regulator give the gas emergency line as 0800 002 001. Do not look up a directory number first.
• The display matches the phone, the mode is Auto, and the boiler still ignores the slots. That is the will-not-fire page: thermostat calling for heat, power, pressure, lockout. A wireless thermostat that has lost its receiver looks like a wrong clock and is not one.
• The screen is blank, the buttons do nothing, or the time will not stay set after a battery you were allowed to change. Open plumbing and heating and read them the badge.
• You rent, and the control is in a locked cupboard or behind a panel you are not supposed to remove. Report the phone time and the display time. Waiting on a wrong hour through a cold week is the landlord’s repair, which you have now described.
• The only problem is a single cold radiator while the clock is right. Use the bleed page, and the pressure page if the gauge is on the floor.

On a call that really is the clock, say the badge, whether DST or automatic time switchover is on, and that the display sits an hour off the phone after 25 October or will not hold a time you set. Ask them to price a controller fault, a replacement programmer, or a diagnosis, and whether the figure includes VAT. A listing that shows Gas Safe is showing a field already on the card. It is not a badge this site sells, and it is not a check that the person is on the register today. You still ask for the licence number when the job goes inside a gas appliance.

City lists are the same directory with a place attached, for example plumbing in Manchester or plumbing in Glasgow. You use the number on the card. The contact-details page only shows how that call works. Nobody here forwards the job, and a guide is not a quote. A programmer that needs a new clock does not, by itself, mean a new boiler or a grant. Pounds for a replacement boiler, and schemes such as the Boiler Upgrade Scheme, live on the cost notes and the grant notes.

The other button people press the same weekend

The clock change is also when fire services ask households to press a smoke alarm. It is a separate button from the programmer. Royal Berkshire Fire and Rescue Service, on 1 October 2026, said fire alarms failed to operate properly in 25 percent of domestic fires in England between April 2025 and March 2026, more than 5,000 failures, and asked people to press the test button weekly, with at least one smoke alarm on every level. The Fire Kills campaign tells tenants to test at least once a month, and says landlords provide the alarms and repair them once told they are faulty. Press each test button until it sounds, including any heat alarm in the kitchen. A carbon monoxide alarm beside the boiler is the other test, on the alarm page, because the heating season is when that sensor earns its place. A silent test button is a battery, a replacement alarm, or a word to the landlord. It is not a heating-clock fault.

Questions that decide the next step

Do heating programmers change themselves on 25 October?

Some do. GOV.UK says the clocks go back one hour at 2am on Sunday 25 October 2026. Worcester Bosch says Comfort controls with DST switched on, and controls that take the time from the internet, move by themselves. A mechanical dial never does. Compare the display with your phone on Sunday morning before you change anything.

Should I set the heating clock back on Saturday night?

Leave it until Sunday morning. On Saturday the country is still on British Summer Time, so a correct clock already matches your phone. If daylight saving is switched on, a manual change on Saturday is then followed by a second automatic change at 2am, and the programme runs an hour late all winter.

The house is cold at the usual time. Is the clock wrong?

After this October change, a clock left on summer time fires an hour early, so the house is more likely to be warm too soon and then cool an hour before you expected. A cold house at the old on-time points at the programmer mode, the room thermostat, the pressure or a lockout. Use the will-not-fire check before you book a clock visit.