Greenstar 2000 System
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.
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.
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.
The type of heating control you need depends on the type of heating system you have. But these are the general types available:
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.
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.
You can check how dirty your system water is yourself by simply bleeding a little into a container from your radiator valve.
Here are the different types of ways your system can be cleaned:
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.
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.
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.
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.
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.
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 £55 and 300kg of carbon dioxide a year, according to the Energy Saving Trust.
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.
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.
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.
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 .
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.