I’m a boiler engineer – what the numbers on radiator knobs really mean and how to cut energy bills


TEMPERATURES have dropped and energy bills have risen – but one simple way to cut bills is to know your way around a radiator knob.

The heating is obviously a large drain on our finances, so knowing the best way to use our radiators cost-efficiently is hugely beneficial.

Boiler expert Mark Ronald shares his heating tips

It may seem obvious, but according to London-based Hometree engineer Mark Ronald, many people forget to turn down the thermostatic radiator valves in any spaces that are unused.

He said: “It is cheaper to only heat the rooms that you need to.

“You can do this by turning down the thermostatic radiator valves in any spaces that are unused.

“It is also important you turn your heating off or down when you are out of the house.”

Using a thermostatic radiator value (TVR) correctly could potentially half you bill, claim experts.

It means you can limit or turn off the flow of hot water in your radiator.

This can help reduce the amount of gas a boiler needs to burn to heat up water in your central heating system.

What do the numbers really mean

The numbers correspond to the temperature in the room, not the temperature of the radiator.

The whole point of a TRV is to detect the temperature of a room and then control how much hot water is let into the radiator.

So if the room is cold, the TRV will sense this and allow more hot water into the radiator to heat up the room quickly.

The number settings on the TRV roughly correspond to the room temperatures below:

  • 0 = 0°C (off)
  • ✱ = 7°C (usually shown as a snowflake or full stop symbol)
  • 1 = 10°C
  • 2 = 15°C
  • 3 = 20°C
  • 4 = 25°C
  • 5 = 30°C

In winter months, households should set TRVs to 2 or 3 in smaller rooms.

And on leaving your heating on all day on a low setting or turning on and off, Mark said: “My advice is always the best way to not waste heat is to ensure you set a schedule on a programmable thermostat.”

“This will set your heating back to a much lower temperature at times you’re out, therefore not costing you money.

“But it makes sure your pipes are protected from freezing if temperatures plummet, as that will add a problem you really don’t want to have!”.

How to save on energy bills

There are more tricks you can do to try and keep energy bill costs down.

To start, one easy thing you can do is change the setting on your thermostat.

Energy experts have revealed the exact temperature to set it at so that you can save cash and keep warm throughout the winter.

When it comes to your thermostat, the Energy Saving Trust recommends you should set it to the “lowest comfortable temperature”.

For the majority of us, this is between 18 and 21 degrees Celsius.

Just by turning down the temp by a single degree you could save as much as £100 a year.

Draught excluders can save you around £30 a year the Energy Saving Trust has previously said.

We’ve spotted them on sale at Amazon for £7.99 before, but of course you should always shop around for better offers.

And you don’t even have to buy one – you can make them for free by filling a large piece of fabric with old clothes or rice.

Switching off so-called “vampire devices”, which drain energy when left on standby or used inefficiently, could save you on your bills as well.

Tips like closing your curtains in the evening also do wonders.

Did you miss our previous article…