Personal Finance

Martin Lewis warns of key thermostat mistake that people make when winter weather arrives | Personal Finance | Finance

The financial journalist gave some advice to listeners to his BBC podcast about how best to use timers and thermostats. As freezing temperatures have arrived in Britain this week, he spoke about a mistake people make when setting their heating because of the cold weather.

He said: “Many people, when it gets cold as it’s happening right now, they turn their thermostat up, with the idea that that will make them warmer.

“Well no it won’t. If your thermostat is set to the right temperature, it’s set to the right temperature.

“Yes, you’re going to have to wait for it to get up to that heat, but don’t start setting your thermostats higher just because it’s colder.

“The thermostat takes you to a certain temperature, that’s its entire raison d’etre. Timers and thermostats are very powerful tools.”

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He also said people often misunderstand the impact turning down the thermostat by just one degree can make on a household’s energy usage.

While admitting this example is not an exact science, the savings expert commented: “Say your thermostat is currently set at 21 degrees and you’re dropping it to 20 degrees, that sounds like it’s not very much. But of course, we’re just comparing it to zero degrees, which is an arbitrary figure.

“In reality, your house may only be heating from 16 degrees up to 21 degrees, and in that case dropping from 21 down to 20 is a fifth of the energy usage, it’s 20 percent of the energy usage. Which is why dropping by one degree can have a really big impact.”

The World Health Organisation recommends 18 degrees as a suitable home temperature for healthy people.


Mr Lewis encouraged listeners to set their thermostat at the temperature that best suits their needs, but also to experiment with turning down the heating if they can.

He said: “You need to set it at the rate that you feel is comfortable for you. Of course, older people and those with medical conditions will want it warmer than that.

“But my suggestion would be, try dropping one degree on your thermostat, see how it feels, and if you don’t notice much difference, that can be a big saving.”

Mr Lewis also told listeners about how they could slash their gas bills by nine percent, by turning down the setting on their boiler.

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He commented: “If you have a gas combi boiler, which is the type most homes have, the flow rate on most of those boilers are set too high as a default.

“The flow rate is the temperature of the water that circulates around the system. If it’s too high, the boiler isn’t operating to maximum efficiency.

“Changing your flow rate can cut gas bills by over nine percent and you won’t notice the change.”

He also mentioned The Money Saving Boiler Challenge, a project which is completely separate from Money Saving Expert, which Mr Lewis founded.

The challenge encourages Britons to turn down the flow temperature on their combi boiler to 60C or below, as this can “knock pounds off your heating bill each year and reduce energy waste from your home”.

Flow temperature refers to the temperature a boiler heats water to before it goes around the radiators of a property.

The Energy Price Guarantee came into effect at the start of October, capping the price of energy but still meaning bills rose significantly, to on average £2,500 a year, for typical households.

The cap relates to the unit price of energy so people in larger households, which use more energy than on average, may well have larger bills.

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