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23 March 2021

Top tips to reduce your heating bills

Expert tips on using heating controls and maintaining your heating system to reduce your energy bills.
person controlling heating with smart app
SM
Sam Morris

We all want our heating to keep our homes cosy and warm, but it would be lovely if it didn’t cost an arm and a leg. Your central heating system is likely to be the biggest contributor to your household bills. Which means there is potential for some big savings.

Follow our top tips to get the best from your heating system – from boiler and radiator maintenance to boiler controls - to find simple ways to cut your energy use and achieve cheaper energy bills.

How to cut your energy costs - reducing heating bills isn't the only way to save money.

Heating and hot water costs

Heating and hot water accounts for about 55% of a household's energy bills, according to the Energy Saving Trust (April 2020). 

With the average home's energy bill being about £1,287 per year*, that's a big chunk of money spent every year heating your home.

It's easy to see how small improvements to your heating efficiency can lead to serious pounds and pence saved.

Additionally, heating accounts for the highest proportion of UK household carbon emissions – higher than transport and aviation!

Data from Energy Saving Trust, based on household emissions in 2017

As we head towards a more sustainable net-zero future, reducing our energy use is a win-win: not only will it save us money, but help save the planet from the impact of climate change as well. 

Ground source heat pumps and Air source heat pumps - really reduce your carbon emissions by replacing your boiler with a low-carbon heating system


1. Update your boiler and heating controls

Old boilers can cost more to run than new ones – but given that buying a new boiler and having it installed can cost up to £4,000, replacing it is not always cost effective. 

If you decide that replacing your boiler would be too pricey but your heating controls are old, just replace those – newer heating controls are much more accurate.

Based on a typical three-bed semi-detached house, there is a potential saving of £75 a year by installing a thermostat, programmer and thermostatic radiator valves (Energy Saving Trust, May 2020).

Not only that, but it could reduce your home's carbon output by 320kg every year.

Types of heating controls

The type of heating control you need depends on the type of heating system you have. But these are the general types available:

  • Timer – turns your boiler on or off at set times
  • Programmer – lets you set different times and temperatures for different days of the week
  • Weather compensating thermostat – adjusts the boiler operation based on the outside temperature
  • Load compensating thermostat – adjusts the boiler operation based on the inside temperature
  • Room thermostat – measures how warm your room is and adjusts the boiler operation accordingly (room thermostats are load compensating thermostats)
  • Thermostatic radiator valves (TRVs) – allow you to adjust the temperature of individual radiators and turn them off completely
  • Smart thermostat heating system – allows you to control your heating remotely via an app. Some are even 'weather responsive' like the Google Nest learning and the Worcester Bosch EasyControl. This allows them to act as a weather compensating thermostat.

Smart heating systems, such as Nest and Hive, are the latest innovation in heating controls. British Gas, which manufactures Hive, claims it could save you up to £120 a year.

But these top estimates assume you are not already being smart about reducing your heating bills. So if, for example, you already turn off the heating when leaving your home, you're unlikely to save as much as the manufacturer's claim.

Are smart thermostats worth it? - find out what happened when we installed Nest and Hive


2. Clean your radiator system

Making sure that your system water (the water that lives in your pipes and radiators) is clean and free of sludge will mean that your heating system is more efficient.

It’s also good for the ongoing life of your boiler and central heating system. 

A clear sign that your system may be overly sludgy is if you have cold spots at the bottom on your radiators, or if some of your radiators take an age to heat up compared with others.

Which? has seen research carried out by Enertek International (an independent company offering innovative services to the gas, oil and renewable heating industry) that suggests a heavily sludged heating system can increase your bills by as much as 25%.

If you're getting a new boiler, a clean system is also essential to validate the manufacturer's warranty on your new boiler.

Ensure that your installer completes the Benchmark commissioning documentation to confirm that this has been done.

Best Buy Boilers - discover the top boilers from the best boiler brands

How to check your radiator system is clean

You can check how dirty your system water is yourself by simply bleeding a little into a container from your radiator valve. 

However, be aware that much of the dirt in the system will sit at the bottom, so bled-off water may appear to be quite clear, even in dirty systems.

Does my radiator system need a power flush?

Here are the different types of ways your system can be cleaned: 

  • Gravity flush: A gravity flush can be done yourself if you're a competent DIY enthusiast. It simply means draining the water in your radiator system and replacing it with new clean water.
  • Power flush: A power flush will be more effective at removing sludge from your system, but it does require specialist equipment and can be expensive. A power flush should cost around £250 for a five radiator system and an additional £30 for every additional radiator.
  • Chemical flush: A chemical flush is a lighter clean with a chemical that will help to more gently ease the muck out of the radiator. A chemical flush doesn't require high pressure equipment, so should be a bit cheaper than the full power flush treatment.

After either of these processes, a chemical inhibitor should be added to the system water to prevent further sludge build up. This should cost around £20 and will help to protect your system water. 

It's important to remember that if you ever add system water to top up the pressure of your boiler system, then more inhibitor will need to be added to keep the concentration at the correct level.

Products like magnetic filters, which cost from £90, can also be very effective at keeping your system water in a good state. They capture materials within a sealed system, that predominantly come from the radiators, and keep your system water clean.

Some boiler manufacturers, like Worcester Bosch, offer a longer warranty on some of their boiler ranges if installed with a filter.

In areas with particularly hard water, a water softening filter is a sensible precaution to prevent limescale build up on critical boiler parts - such as the hot water heat exchanger. 

Signs you need a new boiler - if your boiler is on the blink, see if it's time for an update


3. Check your radiators are balanced

You could have clean system water, but a shoddily balanced heating system will result in you spending more money heating up your home than you need to. 

Are your radiators balanced? The image above shows the impact of an unbalanced heating system on a typical household.

In an unbalanced system, when you set the thermostat to 20°C, the upstairs might actually reach 23°C. While downstairs, where most of us spend the majority of our day, will still be too cold.

If you turn the thermostat up, until downstairs reaches a comfortable temperature, then upstairs is overheated, resulting in a thermostat that’s set at too high a temperature, leading to higher bills.

Turning down your thermostat down by just one degree can save you £60 - 80 a year on your heating, according to the Energy Saving Trust.

If you are having a new boiler installed, your system will need to be re-balanced. After the installation, you should insist that your heating engineer provides proof that your system has been balanced before paying for the installation.

Ask to see the engineer's benchmark agreement, or simply run the heating for a few hours to check that your system is properly balanced.

How to get the best boiler installation - tips on what to ask your heating engineer


4. Put your boiler on the correct settings

You only really need to have your boiler on its highest setting in the very depths of winter. Otherwise your boiler is needlessly heating water up to a very high temperature and wasting energy.

It could also mean that your condensing boiler doesn't even condense. The easiest way to make sure your boiler is condensing is to not set the temperature of the boiler too high. A water temperature of 70°C on the boiler should ensure that it condenses.

However, if you have a dirty or poorly balanced system, then this will also impact on the return temperature of the water to your boiler, and its ability to condense.

Is your boiler actually condensing?

Condensing boilers recover heat that would usually be lost from combustion gases, by condensing water vapour within the gas. This releases heat energy which is then transferred into the cooler, returned water from your radiator system.

All modern boilers, whether they're combi boilers, system boilers or heat-only boilers, are condensing boilers. If you're not sure if you have a condensing boiler or not, check to see if your boiler has a condensation drain pipe, like the one above, in addition to the flue gas pipe. If there's no condensation pipe, you don't have a condensing boiler.

Condensing boilers are at least 10% more efficient than old style boilers, so can save you substantial amounts of money each year on your heating bills.

Critically, condensing boilers only condense if the return water is at around 55°C or lower. If it's at a higher temperature than this, then your boiler is not condensing.

Somewhat depressingly, due to poor installations, there are thousands of condensing boilers installed every year that do not condense. So they do not deliver the promised efficiency gains.

If you want to know whether your condensing boiler is condensing, you can check the temperature of the water return flow pipe (or inflow pipe) with a digital thermometer.

Consult your boiler's guide to identify the inflow and outflow pipes, and simply measure their temperatures with your digital thermometer.

A healthy heating system will have about a 20°C difference in temperature.

Best and worst boiler brands - check before you change your boiler


5. Programme or time your heating

A timer allows you to schedule when your boiler turns on and off over a 24-hour period, so you don't have to do it manually yourself. A programmer gives you even more options, allowing you to set different times and temperatures throughout the week.

If you are buying a new programmer, look for one that lets you set different temperatures for each part of the day. Then customise the pattern for each day of the week.

When you're setting up your heating schedule, don't forget to keep it switched off at times when you might be home and not need the heating on. Such as during the night.

Consider setting it to switch the heating off 20 minutes before you usually go out, as there will still be residual heat in your home.

It's a good idea to choose a model that also lets you override your normal pattern, so you can easily switch off your heating if you decide to head out for the evening or plan a few days away from home. This allows you to change your heating pattern without completely reprogramming the whole week.

Going one step further than this are smart thermostats. As with a timer, you can programme your heating ahead. But with a smart thermostat, you can also override the timer and turn your heating off from your phone.

So if you're running late getting home from work, you won't waste money on energy by warming up an empty house.

How to choose the best energy company - make sure you're getting the best deal


6. Get the best from your thermostats

It may seem obvious, but turning down the heating in rooms will save you money.

Even if you turn it down by just 1°C, a typical home can save around £60 and 310kg of carbon dioxide a year, according to the Energy Saving Trust (April 2020).

Thermostat temperature tips

  • Set the room thermostat to 18°C and then turn it up by one degree each day until you find a temperature you're comfortable with. Note that the temperature shouldn't drop below 16°C for elderly people and those with impaired mobility.
  • Room thermostats need a free flow of air to sense the temperature accurately – they must not be covered by curtains or blocked by furniture. Nearby electric fires, televisions or lamps could also stop them from working properly.
  • Many room thermostats are for one room only, and will turn your boiler off when the room it's sited in reaches the set temperature. For this reason, it's best to install your thermostat in a room that you use all the time.

Boiler controls and thermostats - learn more about how you can control your heating


7. Zone your heating

Instead of just having one room thermostat, you can have separate heating circuits, each with their own room thermostat or programmer. This allows you to zone the temperatures in different areas of your house.

If you have a smart thermostat, you can use smart radiator valves to create heating zones in different rooms as well.

Setting lower temperatures for parts of your home that you use infrequently – such as a spare bedroom - or to only heat at certain times of the day, like an office, will save energy and money.

Best Buy smart thermostats - discover the models that performed best in our lab tests


8. Set your thermostatic radiator valves low

As with your room thermostat, you should set the thermostatic radiator valves (TRV) in each room at a low level, then gradually turn them up until the room's left at a comfortable temperature.

Turning a TRV to a higher setting will not make the room heat up any faster – that depends on the boiler size and setting, and the radiator size. All it will do is keep heating the room until it’s at the temperature designated by the TRV.

Despite their name, radiators actually work by convection. This means cold air enters at the bottom, is drawn through the radiator and hot air leaves through the top.

You can reduce your heating costs by ensuring each radiator in your home is able to circulate heat properly. For example, moving furniture away, not using cabinets to disguise them, and making sure they're not covered by curtains.

You can also get smart radiator valves that you can adjust from your phone.


9. Consider installing a low-carbon heating system

From mid-2030’s the government plans to phase out the installation of fossil fuel gas boilers. From this date newly installed heating systems will need to be low-carbon or able to be converted to use clean fuel.

However, this transition will result in cleaner heating, and potentially huge savings on energy bills.

The initial costs of installing low-carbon heating systems, such as heat pumps, are generally higher than new boilers, but there is currently financial support for installing renewable heating systems such as the Green Homes Grant.

So if you have the money for the initial installation you could make huge savings in the long run and start a more sustainable lifestyle today.

Renewable energy guide - learn about the technology that will be heating our homes in the future


* Department for Business Energy & Industrial Strategy - based on an average annual electricity bill of £705 (standard electricity, fixed consumption levels of 3,600kWh) and £582 for an average annual gas bill (fixed consumption levels of 13,600kWh)


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