Why is my gas bill so high?
Gas is heating, and heating follows the weather. A winter bill four or five times the summer one is normal — which makes the useful question a narrower one.
First, the seasonal effect
In a gas-heated home, roughly 80% of gas goes on heating and hot water. A cold January can use four or five times the gas of a mild July, and a bill that arrives after a cold snap will reflect that.
So compare like with like. A January bill against last January, not against October. If you pay by fixed monthly direct debit, a large winter bill may simply be the account catching up with a balance built through the summer.
Is the reading estimated?
The same first check as electricity, and for the same reason. Gas estimates drift further than electricity ones because usage varies so much by season — a model that assumes an average month will be badly wrong in both directions.
Send an actual reading before anything else. See how to read a gas meter.
Check the conversion, not just the cost
Gas has an extra step where things can go wrong: your meter measures volume and your bill charges energy. If the meter type is recorded incorrectly — imperial read as metric or the reverse — the error is a factor of 2.83, which is unmistakable once you look for it.
Work it out yourself with the gas cost calculator, using the calorific value printed on your own bill so the answer is comparable.
Then the heating itself
Free changes, roughly in order of what they are worth:
- Match the schedule to when you are actually in. Heating an empty house is the largest avoidable cost in most homes, and programmers are often still set for a household that has changed.
- Check the room thermostat. Each degree is worth several percent of the heating bill. Turning it down one degree is worth more than most gadgets.
- Check the flow temperature on a condensing combi boiler.Many are left at 75–80°C when around 60°C lets the boiler condense and run more efficiently. This is the radiator dial on the boiler’s own control panel. It does not apply to a system with a hot water cylinder, to a heat pump, or to a non-condensing boiler, and the hot water setting should not be lowered where a cylinder is present. If you are unsure which you have, leave it and ask at the next service.
- Close doors to rooms you are not heating, and turn their radiator valves down rather than off entirely.
What not to attempt
Do not work on a boiler, a gas appliance or any gas fitting. Gas work by anyone who is not Gas Safe registered is a criminal offence, and the risks are carbon monoxide and explosion rather than a bad repair. Everything on this page is limited to controls a householder is meant to use.
If your boiler is short-cycling, making unfamiliar noises, or the pressure keeps dropping, that is an engineer’s job and it is also a bill issue — a boiler working badly costs more to run.