Heating & Water Efficiency Types
The latest on energy-efficient boilers to save you energy and money, and the right controls to use as little energy as possible, whatever the age of your boiler. No boiler? Find out about controls for electric systems too.
Saving Money On Heating
Understanding your system
In a typical UK household, well over half the money spent on fuel bills goes towards providing heating and hot water. So in these times of ever increasing fuel costs, having an efficient and cost-effective heating system is vital – and it’s one of the main steps you can take to reduce your carbon dioxide emissions.
The first step to saving energy from heating is to understand your current system. Nearly all homes in the UK have either a central heating system – a boiler and radiators – or they use electric storage heaters.
Central heating – a boiler and radiators
This is the most common form of heating in the UK. A single boiler heats up water that is pumped through pipes to radiators throughout the house as well as providing hot water to the kitchen and bathroom taps.
Most boilers run on mains gas but, in areas where mains gas is not available, the boiler can run on oil, LPG (tank gas), coal or wood. Mains gas is usually the cheapest of these fuels, and it also has the lowest carbon dioxide emissions apart from wood. Some boilers also have an electric immersion heater as a back-up.
Gas, oil and LPG boilers may be combination (combi) boilers, in which case they heat the hot water as it is needed and don’t need to store it. Otherwise, the boiler heats up water and it is is stored in a hot water cylinder that then feeds the taps.
If you have a system like this, you have plenty of options for energy-saving improvements:
• Replace your boiler with a newer, more efficient model.
• Fit better controls for your space and water heating – and use them to make sure your boiler only provides heat where and when you want it
• Switch to a cheaper or lower carbon fuel or technology. Find out about renewable technologies for generating electricity and heat.
• Make any insulation and draught-proofing improvements that you can.
• Use chemical inhibitors to help maintain central heating system efficiency
Using chemical inhibitors in central heating systems can maintain their efficiency – helping to save money on heating bills and reduce your energy consumption.
Corrosion deposits in an older central heating system can cause a substantial reduction in the effectiveness of the radiators, and the system as a whole – up to a 15% reduction. The build-up of scale in heating circuits and on boiler components can cause a reduction in efficiency too. Using an effective chemical inhibitor can decrease the corrosion rate and prevent the build-up of sludge and scale – preventing system deterioration and helping to maintain efficiency. Typically, it can increase boiler efficiency by around 3%.
Condensing boiler or not?
Since 2005 virtually all gas boilers that have been fitted in the UK have been more efficient, condensing boilers. Condensing boilers have bigger heat exchangers that recover more heat from the burning gas, making them more efficient. You can tell if your boiler is a condensing boiler with a few simple checks:
• If the flue is made of plastic, you have a condensing boiler. If it is made of metal you probably haven’t.
• If your boiler has a plastic pipe coming out of the bottom of the boiler, through the wall and into a drain, then it is a condensing boiler.
• If you have a gas boiler and it was installed after 2005, then it is almost certainly a condensing boiler.
• If you have an oil boiler and it was installed after 2007, then it is almost certainly a condensing boiler.
• If you don’t already have an efficient condensing boiler, consider replacing your boiler with a newer, more efficient model.
Combi or regular?
Central heating boilers can be combination or regular. They heat the radiators in exactly the same way, but provide hot water for the taps in different ways:
• A combi (or combination) boiler provides hot water directly, whenever it is required, and does not need a hot water cylinder
• A regular boiler provides hot water when the programmer tells it to, and then stores it in a hot water cylinder until it is needed.
So if you do not have a hot water cylinder, you have a combi boiler.A regular boiler is actually more efficient than a combi at producing hot water in the first place, but some heat is inevitably lost from the hot water cylinder, so a combi may be more efficient overall.
Electric storage heaters
Most UK homes that don’t have a boiler and radiators have electric storage heaters. These heat up overnight using cheaper off-peak electricity, and then give out the heat during the day. Electric storage heating is more common in flats, in rented property, and in homes with no mains gas connection.
Electric storage heating is one of the most expensive heating options in the UK, and it also emits more carbon dioxide than most. It is also harder to control electric storage heaters than radiators, especially with older systems. If you have storage heaters, you will probably have a hot water cylinder heated by one or two immersion heaters. If you have a system like this, you have several options for improvements:
• Install new, more controllable storage heaters
• Fit thermostats and controls to make your existing system more efficient.
• Look into making insulation and draught-proofing improvements.
• Replace the whole lot with an efficient boiler system.
Radiators or storage heaters provide the main heating in the vast majority of houses in the UK. However, a number of different technologies are used instead, or as well, including underfloor heating, solid fuel stoves, range cookers, open fires, electric fires and gas fires.
Saving Money On Water
Did you know that much of your water use at home contributes to your energy bill? Each household in the UK uses on average around 360 litres each day. But about 21% of a typical gas heated household’s heating bill is from heating the water for showers, baths and hot water from the tap. This is on average about £140 per year.
Saving water can reduce your water bill (if you’re on a water meter), reduce your energy use and bills, reduce the impact on your local environment, and reduce carbon dioxide emissions by using less energy to pump, heat and treat the water.
When we use water, we are often using energy – mostly to heat the water. Generating energy produces carbon dioxide emissions – and carbon dioxide is one of the main greenhouse gases which causes climate change. Heating water for use in our homes makes up about 4% of the UK’s total carbon dioxide emissions.
No one likes to waste water. However, many of us don’t realise their water usage contributes to energy bills. Simple water use changes can save you money – find out now.
Water heated by a boiler
In most homes, the hot water is supplied by the main central heating boiler, either directly if it is a combi boiler, or from a hot water cylinder. Often there will be an electric immersion heater in the cylinder as well.
Tip – use the boiler to heat the water, even in the summer. The immersion heater will be more expensive, and should only be used as an emergency back-up.
Water heated by immersion
In some homes, particularly those with electric storage heaters, the water can only be heated by immersion heater. There may be two immersions, one in the top of the cylinder and one in the bottom. Usually the bottom heater comes on at night, and heats the whole cylinder using cheap off-peak electricity. The top heater is used to provide additional hot water during the day if required, using expensive peak rate electricity.
Five steps to saving money on your hot water bills
• Use less
• Insulate your hot water cylinder – a well fitted tank jacket could save you around £20 to £30 a year, more if you heat your water electrically. Insulating the hot water pipes will save more energy, and can help your taps to run hot more quickly. Find out more about tank and pipe insulation.
• Control – make sure you have the right controls, and have them set correctly to give you enough hot water when you want it, and not when you don’t. Find out more about boiler controls, and controls for immersion heaters.
• Fuel switching – gas is cheaper than electricity or oil, so consider switching if you can. Find out about improving or switching an electric system.
• Solar – once fitted, solar water heating could provide a good proportion of your hot water requirements with virtually no running costs.
Passive Flue Gas Heat Recovery Device (PFGHRD)
If you have a combi boiler, you may not be able to fit solar water heating, but you may be able to fit a Passive Flue Gas Heat Recovery Device (PFGHRD). This recovers additional heat from the boiler’s flue gases and uses it specifically to heat the hot water supply.
Replacing Your Boiler
Boilers account for around 55% of what you spend in a year on energy bills, so an efficient boiler makes a big difference. Replacing an old gas boiler with an A-rated high-efficiency condensing boiler and improving your heating controls will significantly cut your home’s carbon dioxide emissions – and could save you as much as £305 a year.
Why are new boilers more efficient?
Modern boilers are more efficient for several reasons, but their main advantage is that they are all condensing boilers. All well-maintained boilers burn their fuel very efficiently, but they inevitably lose some heat in the hot gases that escape up the flue. A condensing boiler has a bigger heat exchanger, so it recovers more heat, sends cooler gases up the flue and is more efficient.
Sometimes the flue gases get so cool that the water vapour in the gas condenses out (hence the name). When this happens, even more energy is recovered from the condensing vapour, and the efficiency gets higher still.
Installing a new boiler
If it is time to change your boiler, then the first thing is to decide what type of boiler you need.
The right fuel
If you have mains gas, then a gas boiler is usually the cheapest heating system for you.
If you currently have an oil, LPG or coal boiler, then it might be worth looking into the cost of getting gas supplied to your home. If there is no gas pipe near your home then this is not an option, but if it’s available just round the corner then it might be worth paying for a new connection to get cheaper fuel.
You could also consider a wood-fuelled or biomass boiler. These burn logs, pellets or chips, and are connected to your central heating and hot water system; some models can be automatically fed. Installation costs can be high, but if you replaced electric heating with a wood-burning system you could save as much as £1,050- £1,595 a year in a 4 bedroom detached home.
The right boiler
Most old gas and oil boilers are regular boilers – they have a separate hot water cylinder to store hot water, rather than providing it directly from the boiler. When you replace your boiler you have a choice of buying a new regular boiler, and keeping your hot water cylinder, or buying a combi boiler that doesn’t need a cylinder.
A regular boiler is actually more efficient than a combi at producing hot water in the first place, but then some heat is lost from the hot water cylinder, so a combi may be more efficient overall. The best option for you will depend on a number of factors:
• How much hot water do you use? A large family using lots of hot water could be better off with a regular boiler – a smaller household using less may be better off with a combi.
• Are you short of space? A combi boiler doesn’t need a hot water cylinder, and so needs less space.
• Are you thinking of installing solar water heating? Many combis are not compatible with solar water heating or cannot use it so effectively.
Once you’ve decided on the type of boiler, you then need to make sure that you choose the most efficient model and get it installed safely and legally.
Thermostats & Controls
The right heating controls will let you keep your home at a comfortable temperature without wasting fuel or heat – so you’ll reduce your carbon dioxide emissions and spend less on heating bills.
If you have an electric storage heating and hot water system, with storage heaters use the off-peak electricity to ‘charge up’ overnight and then release heat during the day, you’ll need a different set of controls. Find out more about electric heating and hot water controls.
If your home is heated by a system of water-filled pipes and radiators running from a boiler, you have a ‘wet’ central heating system, whether it is gas, LPG or oil-fired. Your full set of controls should ideally include a boiler thermostat, a timer or programmer, a room thermostat and thermostatic radiator valves
How much can you save?
Whatever the age of your boiler, the right controls will let you set your heating and hot water to come on and off when you need them, heat just the areas of your home you want, and decide how warm you want each area to be. Here are the average savings you could make in a typical three-bedroom semi-detached home, heated by gas:
• Installing and correctly using a room thermostat and thermostatic radiator valves could save £70-£150 and 310kg to 630kg carbon dioxide a year.
• Fit a hot water tank insulation jacket: £20 to £30 and 90kg – 130kg carbon dioxide a year.
You can also make savings by using your controls more effectively:
• Turn down your room thermostat by one degree: save around £75 and 310kg carbon dioxide a year.
You can upgrade or install heating controls without replacing your boiler, and it’s a particularly good idea to think about this if your controls are over 12 years old. Room thermostats, for example, are much more accurate than they used to be.
These prevent your home getting warmer than it needs to be: they will turn the heating on until the room reaches the temperature you have set, and then off until the temperature drops.
Room thermostats need a free flow of air to sense the temperature, so they must not be blocked by curtains or furniture, or put near heat sources.
Your room thermostat should be set to the lowest comfortable temperature – typically between 18°C and 21°C. Try turning your thermostat down a degree or two and seeing if you still feel comfortable. You don’t need to turn your thermostat up when it is colder outside: the house will heat up to the set temperature whatever the weather. It may take a little longer on colder days, so you might want to set your heating to come on earlier in the winter.
A programmable room thermostat combines time and temperature controls and allows you to set different temperatures for different times of the day. You can have different temperatures in individual rooms by installing thermostatic radiator valves (TRVs) on individual radiators
Thermostatic radiator valves (TRVs)
Thermostatic radiator valves do not control the boiler: they just reduce the flow of water through the radiator they are fitted to when the temperature goes above a certain setting. Set them to the level you want for the room: a lower setting uses less energy and so will save you money.
Please note: We would not recommend using radiator covers because thermostatic radiator valves (TRVs) sense the air temperature around them and control the flow rate depending on what level they’re set at. Having a cover over the radiator means that the TRV is enclosed, which is likely to make it think that the room temperature is higher than it actually is – because heat will be trapped between the radiator and the cover.
If you already have a radiator cover that cannot be removed, then it is still worth using TRVs to control the temperature as much as possible, although the radiator will be more effective at heating the room space without the cover. If you feel the radiator is not hot enough at a particular setting, turn up the TRV.
Save money by not overheating parts of your home that are unoccupied or need lower temperatures – bedrooms or rooms with lots of glazing, for example. You can have separate heating circuits with their own programmer and room thermostat (or programmable room thermostat) or set zones by using thermostatic radiator valves (TRVs).
If your hot water is stored in a cylinder, the thermostat will prevent it being hotter than it needs to be. Once the water has reached the temperature you have set, the heat supply from the boiler will be turned off.
Turning the thermostat higher will not make the water heat up any faster, and the water heating will not come on if a time switch or programmer has switched it off.
Cylinder thermostats are usually fitted between one quarter and one third of the way up the cylinder. They have temperature scales marked: you should set them at between 60ºC and 65ºC. This is hot enough to kill off harmful bacteria in the water, but it s also hot enough to scald. For extra safety consider installing a thermostatic mixing valve which will automatically ensure that hot water is at a safe temperature.
Your boiler will usually have a dial on it, marked in numbers or from Min to Max. This sets the temperature of the water that will be pumped from the boiler through the radiators to heat your home. The higher this is set, the quicker and more effectively the system will heat your home. In fact, if this is not set high enough, when it is very cold outside your home may not reach your desired temperature.
If you have a room thermostat and a boiler interlock, you can set the boiler thermostat quite high, letting the room controls do their job. But set it lower if there is anyone vulnerable in the household who might hurt themselves by coming into contact with very hot radiators or pipes.
Your boiler control thermostat should always be set to a higher temperature than the cylinder thermostat. In most boilers, a single boiler thermostat controls the temperature of water sent to both the cylinder and radiators, although in some they are separate.
Programmer or time control
This will automatically switch your heating off when you’re not at home, or when you can do without it, such as when you’re in bed.
Programmers allow you to set ‘on’ and ‘off’ time periods. Most models will let you set the central heating and domestic hot water to go on and off at different times. There may also be manual overrides. Check that the timer on the programmer is correct before you set your programmes. You may also need to adjust it when the clocks change.
Choose a cold evening and time how long it takes for your house to warm up from cold to a comfortable temperature – this is the warm-up time. Then turn the heating off completely and time how long it takes for the house to start to get uncomfortably cold – this is the cool-down time.
You can now set your timers including the warm up and cool down time. So, for example, you can make sure that the heating goes on with a warm-up time before you wake up and turns off before you leave the house. If you insulate your home, it will warm up more quickly and cool down more slowly, so you’ll save money on heating.
If you insulate your home, it will warm up more quickly and cool down more slowly, so you’ll save money on heating.
Set your water to heat up only when you need it: keeping it constantly hot uses energy. If your hot water cylinder or tank is well enough insulated, you may even find that the morning’s hot water stays hot enough to use in the evenings.
What we recommend
Here are some of the controls we recommend to help you effectively control your heating:
• automatic bypass valves
• cylinder thermostats
• full programmers
• programmable room thermostats
• room thermostats
• thermostatic radiator valves
Thermostats & Controls For Electrical Systems
Electricity is the most expensive and carbon-intensive heating fuel available in the UK. The preferred option for anyone with storage heaters is to replace them with a boiler or heat pump, with radiators or underfloor heating. This can cost a considerable amount to install but can save money in the long term.
You could switch to a conventional fuel like gas. A new gas boiler will typically cost around £2,300 plus the cost of the radiators, but you could cut the cost of your heating bill by nearly half and save around £305 a year.
If you don’t have a gas supply to your house but it is available nearby, you may be eligible for a grant towards the cost of having a connection put in. Otherwise you could install an oil boiler and fuel tank.
Or you could switch to a renewable heating system like a heat pump or wood boiler. This will cost you more than a conventional system but you could get payments from the government over the lifetime of the system
Controls for electric storage heaters
Electric storage heaters use off-peak electricity to ‘charge up’ overnight and then release heat during the day.
A standard electric storage heater has two controls, an Output setting and an Input setting. The Output setting will control how much heat the heater gives out (as long as there is stored heat available). The Input control determines how much electricity the heater will take from the grid during the coming night, and hence how much stored heat will be available the following day.
So you need to set the Output dial according to how much heat you want now, and the Input dial according to how much heat you think you will need tomorrow. If a heater runs out of heat in the evening while you still need it, or if the weather gets colder, you may need to turn the Input dial up. If the weather gets warmer, or the heater never runs out of heat in the evening, you can probably save money without getting cold by turning the Input dial down.
Turn the Output dial to zero before you go to bed or go out, so you’re not wasting energy overheating empty rooms. You can probably do this quite early, maybe an hour before you go to bed, as it will take a while for the heater and the room to cool down.
And when summer comes and you don’t need the heaters any more, turn them off at the wall, not just by turning the dials to zero. Remember you will need to turn them on again the day before you need the heating to come back on.
Just like a central heating room thermostat, this helps to keep your rooms at a comfortable temperature. When the air around the thermostat dips below a set temperature, the storage heaters will release heat until that temperature is reached.
Room thermostats need a free flow of air to sense the temperature, so they must not be blocked by curtains or furniture, or put near heat sources.
Your room thermostat should be set to the lowest comfortable temperature – typically between 18°C and 21°C. Try turning your thermostat down a degree or two and seeing if you still feel comfortable.
Your hot water is stored in a cylinder, and the thermostat prevents it being hotter than it needs to be. Once the water has reached the temperature you have set, the immersion heater will turn off.
Cylinder thermostats are usually fitted between one quarter and one third of the way up the cylinder. They have temperature scales marked: you should set them at between 60ºC and 65ºC. This is high to kill off harmful bacteria in the water, but also hot enough to scald, so mix hot water with cold for safe bathing and washing.
A separate hot water time switch will let you heat the right amount of water at the right time – and take advantage of off-peak Economy 7/10 tariffs. By signing up to one of these tariffs, and setting the timer to heat water at a cheaper, off-peak rate, you will use less electricity and save money.
Set your water to heat up only when you need it: keeping it constantly hot uses energy. The better insulated your tank, the longer your water will stay hot.
Most systems have a second, smaller heating element at the top of the immersion cylinder, activated by a boost switch. Use this to heat a small amount of water at expensive peak times during the day.