‘I’m a heating expert – people don’t know what the numbers on their radiator knobs mean’

Most people will have knobs on the side of their radiators which have small numbers on them.

The cylindrical knobs are usually numbered one to five and are known as thermostatic radiator valves (TRVs).

Many people think the numbers on the knobs relate to the temperature of the radiator, however, this isn’t the case. The numbers actually work by responding to the temperature of the room they are in.

With this in mind, Ryan Harrison from energyadvicehelpline.org has shared how to use TRVs correctly so you can save money on your energy bills over the cold winter months.

He explained: “TRVs are common on modern radiators and they work by limiting the amount of hot water that runs into them.

“People assume the numbers equate to how warm you want your radiator – for example, if you’re feeling chilly you might turn your control to five.

“But they actually work by responding to the temperature of the room they are in. When the room reaches the required temperature as set on the valve, they restrict the amount of hot water going into your radiators and this stops them from getting any warmer.

“Zero means the radiator is shut off, while the rest roughly go up in 5°C increments. The exception is the snowflake symbol, which is roughly 7°C.

“The rest are: 1. 10°C, 2. 15°C, 3. 20°C, 4. 25°C and 5. 30°C.”

Ryan said homeowners can benefit from this most by treating radiators in each room differently according to their use.

He said: “TRVs are all about giving the homeowner greater control so they are not spending money on heating up rooms when they don’t need to.

“For example, rarely-used spare bedrooms don’t need to have their radiators set to five. You might be able to set them at one instead.

“Living rooms might be set at two or three, which will allow the space to warm up to a comfortable temperature without your boiler working in overdrive.

“It’s important to remember that little changes such as this can make big savings over the course of the year, which is really important as we head into the colder months and the cost of living is putting even more pressure on people’s finances.”