Your next move could slash or swell your bill.
The row over whether to leave the heating on all day or run it in timed bursts is back. MoneySavingExpert, drawing on advice from the Energy Saving Trust, British Gas and engineers, has offered a clear steer — with a few smart exceptions that matter to your home.
What the MoneySavingExpert verdict means for your bill
For most households, leaving the heating on all day costs more. Heat leaks out steadily, and you pay to replace it. Timed heating that warms the home only when needed usually wins on pounds and pence.
Most homes save money by heating only when needed. Continuous heating increases heat loss and pushes bills up.
That said, some setups buck the rule. Modern condensing boilers and heat pumps often run more efficiently at lower, steady temperatures. If you spend most days at home and your property holds heat well, a constant 18–19°C can compete — or even come out cheaper — than frequent on/off bursts.
The case for timed heating
Timed schedules suit busy households and draughtier homes. You reduce the hours you pay for heat, and you limit the time your house leaks warmth into the winter air.
- Out most days or evenings: heat the house before you arrive, then let it drop when you leave.
- Lightweight walls (e.g., plasterboard on studs): rooms heat quickly, so you gain little from background warmth.
- Older windows and gaps: cut the hours of heat loss rather than feeding it all day.
- Use a programmable thermostat and thermostatic radiator valves (TRVs) to avoid heating rooms you don’t use.
Set schedules around your life: preheat before you wake or return, then let rooms cool when no one’s there.
When “low and slow” can actually win
Some systems prefer a steady pace. Heat pumps deliver their best efficiency when running continuously at lower flow temperatures. Condensing boilers recover more heat from exhaust gases when return water stays cool, which happens with gentle, longer burns.
- Modern condensing boiler (typically post-2005): aim for a lower flow temperature (about 50–55°C) and longer run times.
- Heat pump: target around 18–19°C and let weather compensation fine-tune the flow temperature.
- Well-insulated homes: cavity walls, good loft insulation, and underfloor heating make background warmth effective.
- Home all day: constant comfort at 18–19°C can use less than blasting up from cold.
Aim for a steady 18–19°C instead of yo-yo heating. Don’t crank the thermostat to 24°C to “catch up”.
The physics in plain English
Heat loss rises with the temperature difference between indoors and out, and with time. Keep the house warm for longer, and you leak more heat. That’s why timing often pays. But thermal mass complicates things. Heavy walls and floors soak up heat and release it slowly, which favours steady running. Lightweight rooms warm fast, so timed bursts make sense.
Quick chooser: which approach fits your home?
| Home or system | Likely cheaper approach | Why |
|---|---|---|
| Out most weekdays | Timed bursts | You cut paid hours of heat loss |
| Heat pump with good insulation | Low and slow | Best efficiency at low, steady temps |
| Condensing boiler, radiators, TRVs | Either — test both | Condensing works well at low flow; usage patterns matter |
| Lightweight internal walls | Timed bursts | Rooms warm quickly, little gain from background heat |
| Underfloor heating | Low and slow | High thermal mass likes steady output |
Try it at home: a two‑week experiment
Because every property loses heat differently, run your own test and let your meter decide.
The cheapest method in your house is the one that uses fewer kWh for the same comfort during similar weather.
How the pounds can shift
Illustration, not a promise: a typical gas‑heated semi might use 7,000–9,000 kWh for space heating over winter. If running the system all day raises use by 10–15%, that’s an extra 700–1,350 kWh. At around 7p per kWh for gas, you’re looking at roughly £49–£95 on the season’s bill. Some homes will see less, draughty homes can see more.
Heat pumps change the sums. A steady schedule can improve the coefficient of performance (COP). If careful “low and slow” trims 8–12% off heating use, and your heat pump consumes, say, 3,000 kWh over winter, you might save 240–360 kWh. With electricity at roughly 27p per kWh, that’s about £65–£97. Your insulation, flow temperature and room set‑points drive the outcome.
Cut waste regardless of strategy
- Lower boiler flow temperature to 50–55°C and balance radiators so rooms heat evenly.
- Fit and use TRVs: keep bedrooms cooler, spare rooms lower, living areas at target.
- Schedule sensibly: pre‑heat before you wake or return; avoid heating empty rooms.
- Seal draughts around doors, loft hatches and skirting. Keep trickle vents open for fresh air.
- Close curtains at dusk and tuck them behind radiators; don’t cover thermostats.
- Bleed radiators and service boilers or heat pumps before the deep cold arrives.
- Use a dehumidifier if rooms feel clammy. Lower humidity can improve comfort at a lower thermostat setting.
Condensation, damp and mould: what heating has to do with it
Each time a cold home meets warm, moist air, water condenses on chilly surfaces. Repeated cycles can feed damp. A background 18–19°C helps keep surfaces above the dew point, especially with good insulation. Ventilate kitchens and bathrooms, run extract fans long enough to clear steam, and aim for 40–60% indoor humidity. If you spot persistent moisture on external walls, consider insulation, not just more heat.
Warmth plus ventilation beats damp. Keep surfaces above the dew point and give moist air a way out.
Heat pump pointers
Let the controls do the hard work. Enable weather compensation, keep flow temperatures modest (often 35–45°C for underfloor, higher for small radiators), and avoid frequent on/off cycles. Night‑time set‑backs of 1–2°C usually work better than switching off. Oversized radiators or underfloor zones help the pump sip energy rather than gulp it.
Boiler tweaks that pay back
Condensing boilers gain efficiency when return water sits under roughly 55°C. Start with a 50–55°C flow temperature, run longer cycles, and only raise it if rooms lag behind in cold snaps. Balance the system so distant rooms get their share. Keep hot water cylinder temperatures high enough for safety, but separate them from space heating controls.
Renters and shared homes
If you can’t alter the system, control the bits you can. Use TRVs to zone rooms, add draught excluders that don’t mark paintwork, and set a firm household schedule. Radiator reflector panels cost little and reduce losses into external walls. Keep a simple meter log so housemates can see how habits shift kWh, not just argue about time slots.
A practical way to choose
If you’re at home most of the week, well insulated, and you run either a heat pump or a modern condensing boiler, trial a steady 18–19°C with low flow temperatures. If you’re out a lot, rooms heat fast, or the house leaks warmth, schedule timed bursts around your day. In both cases, trim wasted kWh with draught‑proofing, smart controls and balanced radiators.
One final nudge: measure. Two comparable weeks, matched comfort, and a simple kWh tally will tell you which camp your home belongs to — and by how much. That result beats any rule of thumb on social media.
£300 saving sounds a bit clickbaity‑ish. The maths in the piece suggests more like £50–£100 for many gas homes and ~£65–£97 for heat pumps. Am I missing a scenario where typical usage swings enough to hit £300?