Does Turning Down Radiators Save Gas & Money?

It may be tempting to turn off your radiators in unused rooms.

After all, it would seem logical that by doing so, you’ll save money, right?

Well not necessarily. It turns out that there may be a better approach.

Let’s dive in!

Turning Off Unused Radiators Could Cost More - Here’s Why

It’s true that turning off radiators in unused rooms will likely save energy.

However, it may not reduce your heating bills and might actually increase them!

Why? Because your energy consumption and heating bills don’t always match up as you’d expect.

With all that said, it will depend on when your boiler was manufactured.

On the other hand, if, like most households, you have a modern condensing boiler (or even a heat pump), then it’s a different story.

This is primarily because condensing boilers work far more efficiently at lower flow temperatures.

Flow temperature means the temperature of the water feature in the flow pipe of a heating system or a separate area of a central heating system. 

If you had just one or a few radiators on at once and a high flow temperature, those radiators that are on would be especially hot as would be the fumes being released outside through your boiler flue.

Therefore, you could instead use a lower flow temperature and the energy contained in those hot fumes could instead be used to heat additional radiators.

Put simply, a lower flow temperature = more efficiency = lower heating costs.

Do radiator covers block heat? Check our guide and more energy-saving tips. 

Maintaining or Lowering Your Heating Costs by Using All Radiators

As mentioned, to keep your heating costs the same (or potentially even lower them), you should ensure radiators are used throughout your property and use a lower flow temperature.

Again, the lower the flow temperature, the more efficient your heating system will be.

Please note that for this section we’ll be focusing on keeping radiators on in unused homes if you have a condensing boiler.

PS If you have a heat pump, skip to the next section.

Ideal Boiler Flow Temperature

But how low should it be?

Well, this would depend on what is safe for your home, but essentially you want your flow temperature to be as low as is safely possible.

There is a range of considerations to take into account when determining what this temperature would be such as the type of property you live in and the time of year. 

Here are the ideal flow temperatures on average: *

*If anyone is unwell or otherwise vulnerable in your household, you may need to go higher than the ideal temperatures listed above. If in doubt, consult a professional. Ultimately, your thermostat room temperature is more important for health and well-being. Please see our guide on ideal thermostat temperatures for more details.

How to Achieve This?

Firstly, it’s important to note that there are many smart modulating thermostats on the market that can set the ideal flow temperature for you automatically.

However, otherwise, you’d need to adjust your boiler’s flow temperature. This would depend on what type of boiler you have. It may come with dials, dials and digital displays, or digital displays with buttons.

Whatever the case, you should follow the manufacturer’s instructions to a T if you’d like to adjust the flow temperature. Please take all safety concerns into account.

Another point worth considering is that while you should keep radiators on throughout your property (when you want to heat your home), you could turn down the thermostatic radiator valve or TRV in unused rooms by approximately half a digit.

If in any doubt, check the manufacturer’s guide or consult a professional.

You may potentially be able to set your TRV to a lower level, but it would depend on:

• Your household’s internal wall insulation.

• External household wall insulation.

• How frequently do you leave your property’s internal doors open?

Again, if in doubt, check the manual or make an inquiry with a qualified heating engineer for further information. 

But What Does This Have to Do with Keeping My Radiators On?

You may be a little perplexed as to why keeping radiators on (when wanting to heat your home) helps with this.

Well, this essentially comes down to the fact that maximizing radiator surface area helps with keeping your flow temperature down and increasing efficiency.

With a combination of maximizing radiator surface area and lowering your boiler’s flow temperature, your boiler can utilize more energy from the combustion process (which can then be used to heat rooms via your radiators), while directing less heat to exit through your flue.

Using this approach, your radiators will not be as hot as the ones used would otherwise be, yet nonetheless, heat your rooms as much as is needed.

One way or another, you can expect to at least maintain your heating bills as they are.

So, sure, using less heat energy with a lower radiator surface area seems beneficial at first.

However, with a lower radiator surface area and higher flow temperature, you will still see reduced efficiency.

This could (at the very least) cancel out any gains from turning off radiators in unused rooms.

Turning down your boiler flow temperature could also save you up to 8% on your heating bill, check our new guide on whether to turn the radiators off in unused rooms for another quick and free energy-saving hack. 

What if I Have a Heat Pump?

If you have a heat pump, lowering your flow temperature can be even more beneficial for energy efficiency (and thus maintaining/reducing your heating bills) than would be the case with a condensing boiler.

In the case of a heat pump, it should modulate by itself (thus achieving the optimal flow temperature). If not, consult a professional.