How to Reduce Your Gas Bill: Practical UK Tips

For most households running a gas combi, system or heat-only boiler, the central heating and hot water account for the lion's share of energy use. The good news is that several of the changes that make the biggest difference are free or low-cost, and you can do them yourself today. Below we've grouped the most effective tips, from a quick tweak on your boiler to longer-term insulation work.

1. Lower your boiler's flow temperature

This is the single most overlooked saving. Many condensing combi boilers leave the factory with the central-heating flow temperature set far higher than it needs to be — often around 75–80°C. At that temperature the boiler rarely enters condensing mode, where it recovers extra heat from the flue gases and runs most efficiently.

Turning the heating flow temperature down to roughly 50–60°C lets a condensing boiler condense properly, which can noticeably improve efficiency. Your home takes a little longer to warm up, so it suits people who heat over longer periods rather than short bursts. This is a homeowner-safe adjustment made on the boiler's controls — it is not gas work. For a full walkthrough, see our guide to boiler flow temperature.

Important: lower the heating flow temperature only. Leave the hot water temperature high enough to stay safe against bacteria — never drop it to lukewarm.

2. Set the thermostat sensibly and use TRVs

Every degree on the room thermostat adds up over a heating season. Set it to a comfortable but not excessive temperature — many people are comfortable around 18–21°C — and resist the urge to crank it higher to "warm up faster". A thermostat is a target, not an accelerator; turning it to 28°C doesn't heat the room any quicker, it just runs the boiler for longer.

• Use TRVs (thermostatic radiator valves) to turn radiators down in rooms you use less, like spare bedrooms.
• Zone your home if you can, so you're not heating the whole house to the same level all day.
• Only heat rooms you actually use — closing internal doors helps keep heat where you want it.

3. Use smart controls and a timer

A programmer or smart thermostat lets you heat the home around your routine instead of leaving the heating on constantly. Schedule it to come on shortly before you wake and before you get home, and to wind down before bed. Smart thermostats add features like learning schedules, geolocation (turning heating off when the house is empty) and app control, which make it easier to avoid heating an empty home.

4. Service your boiler

An annual service by a Gas Safe registered engineer keeps the boiler running efficiently and safely, and catches small faults before they become expensive breakdowns. A poorly maintained boiler can burn more gas to deliver the same heat. To understand what's involved and what it typically costs, read our guide to boiler service cost.

5. Draught-proof and insulate

You can lower the flow temperature and tune the thermostat all you like, but if the heat leaks straight out, you're paying to warm the street. Draught-proofing and insulation reduce how much heat you need to produce in the first place.

• Draught-proof doors, windows, letterboxes and unused chimneys with cheap strips and brushes.
• Loft insulation to the recommended depth is one of the most cost-effective upgrades for many homes.
• Hot water cylinder jacket (for heat-only and system setups) keeps stored water warmer for longer.
• Bleed your radiators if the tops are cold while the bottoms are warm — trapped air stops them heating fully. This is a safe DIY job.

6. Keep the system healthy

A few simple, homeowner-safe checks keep your system running as it should:

• Check the pressure on the gauge — typically around 1–1.5 bar when cold, rising toward 2 bar when hot. If it's low, you can usually top it up via the filling loop (check your manual first).
• In winter, a frozen external condensate pipe is a common cause of a boiler cutting out; thawing it gently with warm (not boiling) water often gets things going again.

If you see error codes, leaks, or smell gas, stop and call a professional — never attempt DIY on the gas valve, pipework, flue, sealed circuit, pressure relief valve or boiler casing. For any gas emergency or if you suspect a leak, call the National Gas Emergency line on 0800 111 999 and book a Gas Safe registered engineer.

Quick comparison: effort vs payback

Change	Cost	DIY-safe?
Lower heating flow temperature	Free	Yes
Set thermostat & TRVs sensibly	Free	Yes
Bleed radiators	Free	Yes
Draught-proofing	Low	Yes
Smart thermostat	Moderate	Yes (or fitter)
Annual boiler service	Moderate	Gas Safe engineer only
Loft insulation	Moderate	Often DIY

Where boiler cover fits in

Reducing your gas bill is about efficiency; boiler cover is about protecting yourself from the cost of a breakdown. The two work together — many cover plans include an annual service, which keeps the boiler efficient and helps you avoid surprise repair bills. If you're weighing it up, our explainer on whether boiler cover is worth it walks through the trade-offs.

This article is general information, not financial or technical advice. We compare a selected panel of providers, not the whole market, and may earn a commission if you buy through our links.