FREQUENTLY ASKED QUESTIONS
We have taken the questions we’re asked most frequently at our Call Centre and answered them here for quick and easy reference.
FAQ Categories
- All Questions 54
- Boiler Installation 7
- Boiler operation and maintenance 12
- Boiler Types 7
- Gas safety 1
- General 4
- Heat Pumps 15
- Money Saving 4
- Troubleshooting 6
What size boiler do I need?
As house types and heating systems can vary, it’s always best to seek the advice of a qualified professional when choosing a new boiler. A home survey by a Gas Safe registered engineer is recommended to make sure your new purchase suits you home, your needs and your budget. However, you may want an idea of boiler size options beforehand and to understand which factors to consider when choosing the right one.
The first thing to know is that boiler size relates to its output rating, not the physical size of the unit. In product descriptions you will see outputs referred to as kilowatts or ‘kW’ units which will tell you how much power a boiler can provide to your heating and hot water system.
You will then need to work out your household demands on your heating system and a useful starting point is to consider your property in the following context:
Number of radiators
Number of bathrooms
Number of people
Gas and water supply sizes
This will give you a good starting point on which boiler would best suit your needs and help you avoid the getting the wrong size. An over-sized boiler may be too powerful, leading to performance issues and wasted energy; and one that is too small may not heat your home properly.
For combi boilers, the higher the kW output, the greater the hot water they can provide. A rough rule of thumb would be a 24-28kW combi will supply a single bathroom, a 30-35kW combi will serve a bathroom and ensuite, and 35kW+ combi could serve a two bathroom property.
Is a 30kW boiler a good mid-range output and how can I make accurate comparisons between boiler makes and boiler technologies?
How long does it take to fit a boiler?
This can depend on the extent of the work but here is a rough guide:
If you are simply having a like-for-like replacement boiler installed, then your engineer will usually have all the work wrapped up within one working day.
Should the work be a little more complex, for example if the old pipework is not fully compatible with your new boiler, you should expect the job to take one and a half to two days.
Scenarios that involve moving a boiler much further away from the current position, fitting a different type of boiler or power flushing your heating system will require more time and you will find the process could take up to three days.
It is also advisable to make a little time with the engineer when the installation work is done and dusted so they can take you through the new boiler controls.
If you speak with your qualified Gas Safe registered engineer there will be no nasty surprises as they will provide a time scale before starting the work, so you will know exactly what to expect.
Where should my combi boiler be installed?
Are there restrictions as to where boilers can be sited?
For easier installation and minimal disruption, it is usually best for a new boiler to be sited in the same position as the old one; which often tends to be in or near kitchens and utility rooms. That is not to say boilers cannot be moved to another room if the pipework is correct can be re-connected easily, the flue is in the right position and there is access for maintenance and servicing. However, practical considerations and stringent building regulations will apply, as this guidance explains.
Garage or shed – as these areas can get very cold additional frost protection is critical to combat the risk of pipework freezing.
Loft – a permissible location if the boiler is easily accessible for maintenance and servicing. The downside is that hot water may take longer to reach taps and the flue installation may be more costly due to roof access, etc.
Bedroom – all boilers make some noise and this may bother light sleepers.
Bathroom – a popular location as drainage and waste pipes already exist. However, wiring and gas safety regulations may limit the number of ‘safe zones’ the boiler can go in.
Always consult a qualified Gas Safe registered engineer who will provide expert advice on the best solution for your boiler position and the associated pipework, flue and drainage.
Do boilers require ventilation when installed in a compartment such as a cupboard?
It is common for boilers to be installed inside a cupboard to hide unsightly pipes and fittings. There has even been widespread coverage of a study conducted by Npower that revealed a staggering 57% of people would want £5,000 knocked off the asking price of a property if it had an exposed boiler. The survey also showed that 68% of Brits would be put off buying a property altogether if the boiler is visible.
However, when boilers are concealed in a cupboard it often leads to questions about whether air vents are required. To be clear, Alpha boilers do not require air vents for cooling when installed in a cupboard, provided the minimum clearances shown in the installation instructions are met.
What is the maximum equivalent length of a boilers flue?
Depending on the boiler model and the type of flue, the maximum length could be between 8m and 14m total, less any deductions for use of bends. The specific allowance for bends is 1.3 metres of flue length for each 90-degree bend and 0.9 metres of flue length for each 45-degree bend. The total maximum equivalent flue length is always shown in the boiler instruction manual of every model.
If a flue exceeds the maximum length, then the boiler may not function as it should and could result in serious damage to the boiler, for example, if the ignition is delayed and the combustion is affected.
What do I need to know about boiler flues?
Can 90-degree bends be used on vertical flue systems?
Yes, 90-degree bends can be fitted with our condensing boilers if the correct allowance is made on the maximum flue length. We recommend a 1.3 metre reduction for each 90-degree bend and a 0.9 metre reduction for each 45-degree bend.
If it is necessary to use a 90-degree bend in a vertical flue system, the flue above it should be sloped towards the boiler to ensure that all condensate is allowed to drain from the flue. The slope must be a minimum of 25-30 mm per metre.
A flue is a pipe or duct that carries away your boiler’s exhaust gases and safely releases them from your home and into the atmosphere. These exhaust gases are produced when your boiler burns fuel and must be safely directed.
Does the system need an automatic by-pass valve?
It is essential for the healthcare of a boiler for an automatic bypass valve to be fitted as part of the heating system. A bypass is required to ensure a constant minimum flow rate through the heat exchanger and to dissipate heat on pump overrun. All modern boilers are ‘low water content’ and require a constant flow through them to prevent overheating.
This is particularly important if your heating system includes a large number of Thermostatic Radiator Valves (TRVs) as flow rate is reduced when TRVs start to close or are shut off completely. In this situation the automatic bypass valve will start to open to maintain the required water flow through the boiler. Using an Automatic Bypass Valve is also likely to reduce noise in systems caused by excess water velocities.
Alpha combination boilers already incorporate an automatic by-pass valve and for regular (heat-only) and system boilers your qualified Gas Safe registered engineer will be able to advise what is needed for your system to meet current Building Regulations.
Will turning my water off affect my boiler?
This is a common question as people fear turning off the water will damage their boiler in the mistaken belief that it might overheat, much like a boiling kettle without any water in it.
This is not the case as the water that comes out of your taps is not the same water that passes through your boiler. The water being heated by your boiler is in a closed loop being continually heated, cooled and circulated to warm up your radiators and exchange heat to your tap water.
By turning off the water you will only be cutting off the supply to your taps and, if your heating system has them, to the cistern tanks and storage cylinders.
Combi boilers will continue to provide heating, if required; but with the mains water supply turned off the combi will simply not function for hot water.
If you have a conventional (heat-only) boiler or a system boiler and you turn off the water, it will carry on heating up the radiators. You might even get a little hot water out of the cylinder, but that will quickly cease without any pressure or new water entering the system.
If you wish to turn off your boiler when you go on holiday, consider your decision carefully. While it is safe to do so in Summer, it is recommended that you keep your boiler switched on in Winter when temperatures can get quite low, in order to provide frost protection.
How do I adjust the temperature when the water is too hot?
If the temperature of your hot water is too high for your liking it is relatively simple to adjust it.
It is quick and easy to adjust the temperature on a combi boiler. Locate the digital control panel or temperature dial on the front your boiler and make your adjustments for the hot water (which will not affect the central heating temperature). The result will be instant.
It is a little more involved for conventional (heat-only) or system boilers as you will need to locate the thermostat and adjuster on your storage cylinder. Once the adjustment is made, you will have to wait a few hours to notice the change as your cylinder will be insulated and so take time to cool down.
However, it is not advisable to set it lower than 60°C as that is the minimum temperature required to kill most bacteria in your stored hot water.
The same principles apply when turning the water temperature up but if it is set any higher than 65°C there is an increased risk of scalding.
Should I turn my boiler off at night?
There is no clear-cut answer to this question as there are pros and cons depending on your situation, but efficiency issues tip the balance in favour of not turning your boiler off at night.
Turning a boiler off at night means it must fire up again every morning which tends to use more energy than just leaving the boiler on overnight, especially if the temperature in your home has dropped quite dramatically. As an example, if your boiler is turned off and the temperature drops below 10°C overnight, your boiler will use more energy bringing it back up to 18-20°C in the morning than if it was just left ticking over with the thermostat at 15°C.
A more effective way of saving energy is to set your thermostat to the lowest temperature you are comfortable with so that your boiler only starts itself up when the temperature drops to that specific level.
Do Alpha boilers have a pump overrun feature?
Yes, for safety purposes Alpha boilers are designed to run for a short period after the boiler has switched off. This is to circulate the water so any residual heat can be dissipated around the heating system thus eliminating the risk of the water boiling in the heat exchanger and causing damage.
The pump overrun function lasts for up to 3 minutes in Alpha boilers which is sufficient for the cooling process to take place.
Do Alpha boilers have built-in frost protection?
Yes, Alpha boilers incorporate a built-in frost thermostat. This automatically turns on the boiler and pump if the water in the boiler falls below a temperature of 5°C, provided the electrical supply is on. This function ensures that the boiler will continue to operate until the water temperature in the system boiler reaches approximately 40°C.
This feature is particularly important if your boiler is installed in a garage or loft as will be at a greater risk of freezing.
It is important to be aware that the boiler will ignite when the frost setting is activated so you may see this reflected in your heating bill. However, without frost protection you could be risking a much larger repair bill further down the line if damage is caused.
Can I fill a system with softened water?
It is not recommended that the heating system is filled with chemically softened water (i.e. typically salt based softeners).
The water used to fill a central heating system should always be kept as neutral and un-reactive as possible to protect parts such as aluminium heat exchangers within older boilers, and mild steel radiators which are common in most UK houses. To achieve this only water from a dedicated mains water feed should be used, with corrosion inhibitor chemicals typically added and tested annually.
If you have a water softener system, it should be turned off or put into ‘bypass’ mode when filling the heating system to obviate any issues. Alternatively, the filling loop feed can be connected upstream of the water softener.
The only scenario where softened water is a benefit is when it comes to a combi boiler’s hot water side (which is quite separate to the heating system). This is because softened water helps to keep the hot water heat exchanger clean, whereas calcium-laden water, when heated, can produce scale which drastically reduces heat transfer effectiveness.
Do solar power systems work when the sun isn’t shining?
Yes, our SolarSmart solar thermal system works even on cloudy days because it uses diffused radiation as well as direct sunlight. This means that enough energy can be collected by your solar power system to supply almost all your hot water in Summer and about a third during the rest of the year.
Alpha SolarSmart can be used with any Alpha combi and unlike traditional solar thermal systems it requires no specialist equipment to install and maintain making it a popular option for installers and homeowners alike.
How often do I need to top up the pressure in my heating system?
On rare occasions you may find that your boiler has dropped (or increased) in pressure and this can cause your hot water and radiators to stop working. The good news is that you may be able to correct the problem yourself without having to call out an engineer.
For those who feel confident enough to attempt this we have provided step-by-step instructions for resolving low (and high) pressure issues. These can be found in our article dealing with boiler pressure.
We also have a video guide to topping up combi boiler pressure on our YouTube channel.
As well as safety tips, the guide explains pressure readings and provides clear instructions on every step of the re-pressuring process.
If you are unsure about undertaking these tasks, or if the problem is not remedied by the steps suggested, we recommend calling out a qualified Gas Safe registered engineer.
Why is system cleaning important?
Cleaning a central heating system removes contaminants which would otherwise form a harmful sludge in your heating system which will not only reduce the efficiency of the system, but also create noise and potentially reduce the useful life of your appliance.
There are a variety of contaminants that can build up including residue from compounds used during pipework installation, grease, oxides produced by corrosion, bacteria and, in hard water areas, limescale too.
If you are replacing your boiler then a system clean is essential prior to installation of the new appliance. If this is not carried out there is a serious risk that your new boiler will be contaminated with damaging sludge and debris that was present in old, uncleared pipework.
You may hear system cleaning referred to as “power flushing”, a method that uses a specialist pump during the cleaning process. However, mains pressure and pumped gravity cleaning methods are also acceptable.
How do I prevent or remedy a frozen condensate pipe?
When modern high efficiency boilers heat your home water vapour is created and a condensate pipe is needed to help drain the liquid away from the boiler. Condensate pipes can be situated either internally or externally but, if it is the latter, then it stands a far higher chance of freezing when the weather turns cold.
It is important to defrost a condensate pipe – or, better yet, prevent if from becoming frozen – so that your boiler continues to perform, and you are not faced with costly damage. And the good news is that a range of simple solutions are available.
Preventative measures include retro-fitting pipe insulation or installing an accessory such as the Alpha E-Tec Trace Heating Kit which enables the boiler to work in conjunction with an electric trace wire and outside weather probe to protect external condensate pipes during freezing temperatures.
In the unfortunate event your condensate pipe has frozen it is relatively straightforward to rectify the problem yourself by thawing the frozen blockage with warm water. Take a look at our handy frozen condensate pipes guide for more help.
What does the boiler condensate pipe do and what do I need to know about boiler condensate pipe regulations?
How often should I have my boiler serviced?
It is highly recommended that you have your appliance serviced by a qualified Gas Safe registered engineer once a year.
There are two types of maintenance checks, namely a safety inspection and a service. In a safety inspection the engineer will typically carry out a visual inspection of any gas appliances (i.e. boiler/gas hob/gas fire, etc.), check the air supply is adequate, the flue is functional and the boiler is burning gas correctly/efficiently, and that any safety devices are operating correctly. You could think of this as like an MOT for your car, it simply proves that it passes a safety inspection on that day. It’s worth noting that landlords are legally obliged to have a gas safety inspection on the gas appliances within a rental property at least every 12 months.
A boiler service is more thorough as the engineer will not only carry out safety tests but will also check internal components for wear and carry out cleaning and adjustments where necessary. Most boiler manufacturers state that a boiler service should be carried out at least every 12 months to maintain the boiler warranty.
If possible, Summer is a good time to have these checks as demands on your boiler will be lighter and repairs will cause less inconvenience than in Winter. However, if at any other time you notice signs that the boiler might not be functioning properly, you should have it checked right away.
For further information on this topic, please take a look at the importance of annual servicing.
Is my central heating system covered by the boiler’s guarantee?
It is always important to understand the scope and conditions of any warranty and, as a manufacturer, we believe we should make this information very clear. In the case of our manufacturer warranty for your boiler it applies solely to the appliance supplied, and not to the hot water or central heating system (i.e. taps, showers, radiators, pipework, radiator valves, etc.).
This means that if a fault on your central heating system is having a detrimental effect on the performance of your boiler, it will invalidate the boiler warranty. For example, if your central heating system is full of sludge caused by deposits from rust in your system and it makes its way into the components of your new boiler, the warranty will be void.
What is a condensing boiler?
A condensing boiler is the most efficient form of boiler available as it is able to capture heat from waste flue gases - which would otherwise be released into the atmosphere - and recycle it back into your heating system. This high efficiency is thanks to heat exchangers inside the boiler which, during the heat recovery process, rapidly cool the waste gases and ‘condense’ the water vapour into water droplets (or condensate), which is what gives the boilers their name.
This technology means that a condensing boiler can convert around 90% of the fuel it uses into heat, compared to around 60-70% for non-condensing boilers. In other words, a condensing boiler won’t have to work as hard or burn as much fuel to create heat, which will save you money. On top of this, minimising waste gas emissions makes condensing boilers safer for the environment.
In summary, you could say that the term ‘condensing’ refers to the way a boiler functions, rather than being a type of boiler such as a combination (combi), conventional or system model. But in today’s world, whichever modern high efficiency boiler you choose it will be condensing, allowing you to enjoy economical and environmental benefits.
Are gas fired boilers being phased out?
What is a high efficiency boiler?
High efficiency is the term given to condensing boilers which, thanks to their modern heat-exchange technology, efficiently recover high levels of heat energy from waste flue gases and recycle it back into your heating system. Condensing boilers are so efficient that they can convert around 90% of your boiler’s waste gases into usable heating.
High efficiency condensing boilers have superseded older-style conventional boilers which are non-condensing and are only considered ‘standard efficiency’. This is because they release a lot of waste gases into the atmosphere and only recover around 60-70% of the heat energy making them less efficient and more damaging for the environment. In fact, as a result of this, there have been changes in the law and it is now mandatory for all new boilers in domestic homes to be high efficiency condensing models.
How are high efficiency condensing boilers more efficient than standard efficiency boilers?
High efficiency condensing boilers are able to capture and use much of the heat that old non-condensing boilers waste and release into the atmosphere. Condensing boilers convert around 90% of fuel into useful heating, whereas old conventional boilers only convert around 60% and waste the rest. All new gas boilers in England and Wales must be condensing boilers.
What is a combination boiler?
What is a combination boiler?
A combi boiler is a single unit that provides a ‘combination’ of both hot water and space heating, and it is the most popular type of boiler in the UK. They heat hot water directly from the mains when you turn on a tap, which eliminates the need for a cold-water storage tank in the loft and a bulky hot water cylinder which would otherwise take up space. And, by not storing hot water in a tank, you only heat the water you use, thereby reducing your energy bills as well as your carbon footprint. Key features of a combination boiler:- Combi boilers heat up water on demand and do not require a bulky water tank or a hot water cylinder
- They are considered the best choice for small to medium size properties with average hot water demands
- Energy is not wasted by heating water that may not be used, thereby reducing your heating bills and your carbon footprint
- They are quick and easy to install
- They are the most popular type of boiler in the UK
What is a system boiler?
Just like conventional boilers, system boilers are ideal for multi-bathroom properties with high hot water demands but the key difference is that they take up less space.
You will still need a hot water storage cylinder to ensure the hot water is always readily available, but the feed and expansion (usually located in the loft) is replaced by an expansion vessel which will be housed in the boiler, along with the circulation pump and some of the valves. Having more components built into the boiler like this makes them easier to install than conventional boilers.
It’s worth considering that using an unvented hot water cylinder alongside a system boiler can provide good hot water delivery but comes with its own special installation requirements so you should always seek advice from a qualified tradesperson before choosing this option. However, if you have sufficient space and can meet the installation requirements, this could be just the solution for you.
What is a conventional boiler?
Also called ‘regular’ or ‘heat-only’ boilers, conventional boilers provide central heating and stored hot water and are very common in traditional heating systems throughout the UK. and are the ‘go-to’ choice for larger homes with a high demand for hot water. They enable your household to run hot water from several taps simultaneously without a significant drop in pressure. They are also a cost-effective solution if your property previously had an older heating and hot water system and existing pipework is still in place.
What is a heat-only gas boiler?
More space is needed for conventional boilers but, as they are most popular for larger properties, this is not usually a problem. Requiring three tanks, this system typically has:
A cold-water cistern to store cold water (typically in the loft)
A small feed and expansion cistern to maintain the water level of the heating system (usually next to the cold-water cistern)
An insulated cylinder to store hot water (most often located in an airing cupboard)
While conventional boilers offer many benefits, there are some downsides. They do tend to be more expensive to install and are also not quite as efficient as combi boilers as some heat is lost from the water in the storage cylinder. Also, once the hot water has run out, you will need to wait for it to heat up again before using the hot tap.
Should I replace my conventional boiler with a combi?
What is a hydrogen-ready boiler and do I need to get one?
If you want to reduce your carbon footprint and enhance the efficiency of your heating and hot water system, it may be that you have read about the potential of hydrogen boilers as an alternative to natural gas boilers.
Adding hydrogen to the natural gas that flows into our homes is one of several long-term options the Government is exploring as it looks at ways to decarbonise UK heating systems in line with its agenda for reaching net zero carbon emissions by 2050. One method is to blend 20% hydrogen gas into the natural gas. This could be safely transported through the pipes in our existing gas network, which would save the costs and time of building a new delivery system.
However, the boilers in our homes are designed to run on 100% natural gas. As a result, manufacturers such as Alpha Heating Innovation, are developing boilers which are hydrogen-ready so that they run on natural gas in the usual way but can safely utilise this blend of natural gas and hydrogen with a small adjustment by a Gas Safe engineer.
There has also been some discussion of eventually switching to a 100% use of hydrogen gas for heating and hot water production in homes. In reality, hydrogen is unlikely to be widely adopted into UK heating systems for many years, perhaps even a decade. And while Alpha support on-going research into this area we remain dedicated to meeting the demands of today’s customers whose homes need to be heated by domestic gas boilers.
Our advice to customers is that you don’t need to go out and buy a new hydrogen-ready boiler right now. But if you do decide to replace an older boiler in the next year to five years, then it is worth speaking to your installer about a hydrogen-ready option.
For further information on this topic please take a look at our article Hydrogen-ready boilers - planning ahead.
What is carbon monoxide poisoning?
You should get your boiler checked immediately if you notice any signs that may indicate carbon monoxide poisoning. Carbon monoxide is a highly poisonous gas that is responsible for killing around 50 people a year in the UK. As it can easily go undetected due to lack of colour, scent or taste, it is important to be aware of possible symptoms:
Headaches
Dizziness
Nausea and vomiting
Tiredness
Stomach pain
Shortness of breath and difficulty breathing
Confusion, fast and irregular heart rate and seizures
These symptoms can be mistaken for food poisoning, viral infections or the flu, but if the symptoms disappear when you leave your house, you should have your boiler checked. As a safety precaution, it is advisable to purchase an audible carbon monoxide alarm; available from most DIY stores and costing between £20-30.
Boilers installed and regularly serviced by a qualified Gas Safe registered engineer will be safe and reliable. However, if a boiler has been fitted badly or not properly maintained, there will be warning signs if it isn’t working properly:
Lazy yellow flames on your gas appliances rather than a crisp blue one
Pilot lights that frequently blow out
Excessive condensation on windows
Unusual dark marks or staining around or on gas appliances
For further information on this topic, please take a look at our articles on carbon moxoxide poisoning and gas safety awareness in the home.
How long does a boiler last?
The average lifespan of a boiler is 15 years and, if you keep it in top condition, it can last even longer.
The best way to look after your boiler is to have it serviced by a qualified Gas Safe registered engineer once a year. Summer is a good time for this as demands on your boiler will be lighter and any repairs will cause less inconvenience than in Winter. However, if at any other time you notice signs that the boiler might not be functioning properly, you should have it checked right away.
There are two types of maintenance checks, namely a safety inspection and a service. In a safety inspection the engineer will typically carry out a visual inspection of any gas appliances (i.e. boiler/gas hob/gas fire, etc.), check the air supply is adequate, the flue is functional and the boiler is burning gas correctly/efficiently, and that any safety devices are operating correctly. You could think of this as like an MOT for your car, it simply proves that it passes a safety inspection on that day. It’s worth noting that landlords are legally obliged to have a gas safety inspection on the gas appliances within a rental property at least every 12 months. A boiler service is more thorough as the engineer will not only carry out safety tests but will also check internal components for wear and carry out cleaning and adjustments where necessary. Most boiler manufacturers state that a boiler service should be carried out at least every 12 months to maintain the boiler warranty.
What does a gas boiler service involve, and why do I need one?
What should I do with my old boiler if I have a new one fitted?
It surprises some people to know that boilers are not generally considered domestic rubbish and may not be collected by the local authority if left at the kerbside with your standard household waste. Here are some options available:
The company or engineer who installs your new boiler – you can ask them to take your old boiler away. They won’t give you anything for it, but it is a hassle-free solution.
Local recycling centre – some centres have provision to dispose of metals and can recycle boiler components. Always check with your local authority first.
Local council ‘bulky waste collection’ service – do check first as every council has different rules but some will collect boilers from the boundary of your property for a set fee (ranging from £20-£40).
Scrap yards – the Government no longer offers a scrappage scheme, but your local scrap yard is worth contacting. As the metal can be recycled you could receive a small payment for an old boiler. Copper pipes also have value so, depending on the price of copper at the time, you could earn up to £70.
I am extending my home – will I need a new boiler for the new section of the house?
To ensure maximum efficiency, the capacity of your current boiler should have been carefully matched to the amount of floor space and number of bathrooms in your property at the time of installation.
Whether or not you need a new boiler for an extension will depend on the extent of your renovations. If you are, for example, simply adding one radiator for a new conservatory it is unlikely that you will need to need to replace your boiler. However, if you are extending your home quite significantly and, say, adding a bathroom, it is best practice consult a Gas Safe registered engineer to assess whether your existing boiler is correctly sized, and to discuss with you if any upgrades to the boiler, or gas and water supplies are required.
We suggest contacting a qualified Gas Safe registered engineer to find out if a new boiler is needed and to discuss your options. They can recommend the size and type of boiler that would meet your extra heating and hot water demands and deliver an energy-efficient and environment-friendly solution. They can also assess whether it would be beneficial to relocate your boiler to improve the efficiency of your heating system - although be sure to bear in mind the extra cost for works such as extending and re-routing the pipework, adding a new flue and carrying out redecoration in affected areas.
Will a heat pump save me money?
A heat pump is an energy efficient way to deliver heating and hot water to a home using electrical energy. On average, a heat pump uses 1 kilowatt of electricity to produce approximately 3 kilowatts of heat (exact efficiencies will depend on the size of the system and outdoor temperatures).
So, a heat pump is almost certainly more cost-effective to operate than an oil-based heating system, or a direct electric heating system such as storage heaters, fan heaters or underfloor mat type. For homes that are off the gas grid, an electric heat pump can therefore make a lot of sense in terms of lowering running costs.
UK energy costs in early 2022 mean that the unit rate of electricity is around four times more expensive per kilowatt hour than gas. This means that even though a heat pump is very efficient, in some cases it may be more expensive to operate than a modern gas boiler at this time. But the UK is looking to achieve net zero carbon emissions by 2050, so we are moving away from using natural gas. We are therefore likely to see gas prices rising in the next few years to a point where they overtake electricity prices. At that point, it would make sense to consider lowering energy bills by switching to an energy efficient heat pump.
One option is to consider making your own electricity. As an electric heating system, heat pumps can also be powered from solar panels (photovoltaics). Depending on heating and hot water needs, and the number of solar panels, this could be cost-effective to operate – although the initial costs of installation and suitability of the property would have to be considered.
Is my home suitable for a heat pump?
It’s important to ensure that your home is suitable for making use of a heat pump heating system. It is always best to discuss the options with a heating engineer, as they will also need to correctly size the system before installation.
The first thing to bear in mind about heat pump heating systems is that they operate at lower temperatures than gas boiler systems. A traditional boiler-and-radiator system generally runs at around 70oC to 80oC; a heat pump system recommended temperature is between 35oC to 55oC.
This means that for the heat pump to provide a comfortable indoor temperature, the house must be well insulated. Investing in loft insulation and modern windows and doors would be an important first step if your home does not have these already. You will find that these will go some way to lowering your heating bills, whatever system you use.
You may also have to consider that the lower running temperature of heat pump system might require replacing older radiators with new, larger and more effective models to ensure the system operates efficiently. And if you don’t currently have a hot water cylinder (for example, if you have a combi-boiler that heats water as you need it) then you would also probably have to have one fitted if the heat pump is providing hot water as well as heating. It is important to bear in mind that with an air-source heat pump heating system there is an outdoor unit. These are generally around 1m x 1m x 330mm. Having a garden or outside space is an advantage, but there are units that can fit onto walls or balconies in apartment blocks.
How large is a heat pump and where does it need to be placed in terms of planning, connections and aesthetics?
The outdoor unit of an air-to-water heat pump is around 1m x 1m by 330mm deep. Ideally, it should be placed close to the house with the required clearances to allow good airflow. A spot with few plants nearby is best, as these could block the airflow around the unit and reduce its performance.
The installation of a single air source heat pump on domestic premises is a ‘permitted development’, so it does not normally require planning permission, if the installation complies with the Microgeneration Certification Scheme Planning Standards (MCS 020). Also, the heat pump must also be used only for heating purposes.
The permitted development rule applies to the installation of a new or replacement air-source heat pump for a house or block of flats (where the block consists solely of flats and does not include commercial premises).
It is a good idea to check with your local planning authority to ensure that all these limits and requirements will be met
Are there different types of heat pump?
There are different types of heat pump. The most commonly-used in the UK today are air-source heat pumps which extract heat from the outdoor air. But it’s also possible for heat pumps to extract heat from the earth through a series of pipes laid underground. These are known as ground-source heat pumps. And heat can also be extracted from bodies of water such as rivers or lakes, and water-source heat pumps can be used to do this.
Heat pumps can also deliver heating in different ways. The heat extracted from air, earth or water can be delivered into a home via water or air. An air-to-water heat pump, for example, extracts heat from the air and transfers this to water which flows around the home in radiators or through an underfloor heating system. Alternatively, that heat can be transferred to air which is delivered by indoor units into the house. This would be known as an air-to-air heat pump.
Each method of extracting heat and delivering it has its benefits and drawbacks, so it’s very important to discuss a heat pump system with an expert installer to ensure you are making the best choice for your property and your heating needs. An installer will be able to describe the initial costs of a system and provide information on issues such as operating costs and maintenance requirements too.
What is a heat pump – and how does it work?
A heat pump is a device that takes low-temperature heat from a source such as the outdoor air and increases that heat in an energy-efficient way. This heat can then be transferred, for example, to water that circulates around radiators or an underfloor heating system.
A heat pump uses electricity to drive a compressor that raises the temperature of that source heat energy very efficiently – much like your refrigerator but in reverse. The exact efficiencies depend on size of the system and the outdoor / indoor temperature difference. But, on average, 1 kilowatt of electricity can produce approximately 3 kilowatts of heat. Heat pumps can also transfer heat from sources such as the ground (known as a ground-source heat pump) or water in nearby lakes or rivers (a water-source heat pump).
The most common heat pump found in UK homes today is the air-to-water type. This has an outdoor unit (about 1m wide by 1m tall and 350mm deep) that collects heat from the outdoor air and raises the temperature to heat water for your radiators or underfloor heating. The heat pump can also provide hot water to a cylinder in your home for use in showers and hot taps.
Because they’re electrically powered, heat pumps can make use of the UK’s wind-generated electricity, making them a low-carbon heating system. It is also possible to use electricity from solar panels (photovoltaics or ‘PVs’) which could be mounted on the roof of the house. Unlike a fossil fuel boiler, heat pumps produce zero carbon emissions at your home.
Are heat pumps noisy?
An air-to-water heat pump should not create a lot of noise, if it is operating normally and is correctly installed and maintained.
An air-to-water heat pump has an outdoor unit that contains a compressor which produces the heat for your home. As it operates, it will make some noise. On average, this is between 40 and 60 decibels (dB) which will depend on the size of the heat pump.
For comparison, the Alpha Heating Innovation E-Tec Plus combi boiler range has a sound level between 52dB and 55dB. A normal conversation at 1m away is around 60dB; a modern domestic fridge freezer operates between 40dB to 45dB.
Does a heat pump need regular and/or specialist maintenance?
A domestic air-to-water heat pump has a life expectancy between ten to twenty years. But it requires regular maintenance to ensure your system is working as efficiently as possible. We would recommend having an annual check on your system by a professional – just as you would for a gas boiler.
It’s very important to have your heat pump system designed and installed by a trained professional who understands how to size and set up your heat pump system. It is a good idea to speak to them about long-term servicing requirements.
In general, if you have an air-to-water heat pump it’s a good idea to check the outdoor unit once a month to make sure no leaves or debris have collected near the air inlet. Keeping things tidy will help the unit operate effectively over the long-term.
Do I have to keep the heating on all day if I have a heat pump system?
An air-to-water heat pump system operates at lower temperatures than a traditional gas boiler – 35oC to 55oC rather than 70oC to 80oC. But your system will be designed and installed to work effectively and efficiently with those lower temperatures.
The best approach is to use the timer and temperature controls that come with your heat pump system, just as you would with a gas boiler. This will ensure that your home is comfortably warm and energy efficient.
Unlike a gas boiler a heat pump will take longer to heat house from cold and use more energy making a sharp climb in temperature. So, low-temperature heating is better suited to work continuously, with a designed ‘set back’ temperature for times when the home is unoccupied or at night-time. A recommended set back is 2°C to 3°C.
For example, a temperature during the daytime of 21°C will keep the house and its occupants warm, then overnight or while the house is empty, this can be reduced to a temperature of 18°C to 19°C. It is an energy efficient approach that keeps the home comfortable.
Will a heat pump provide hot water as well as heating?
A heat pump heating system can provide hot water as well as heating for your home. This can be done with a hot water cylinder designed to work with your heat pump. This will be an unvented hot water cylinder that provides high pressure hot water. It is designed with a larger internal cylinder coil to allow for low temperature heat exchange, to make the most of the heat pump’s energy efficient technology.
If you currently have a combi-boiler, which doesn’t have a cylinder as part of your system, then you will need to have a cylinder installed with the heat pump. This will be fitted inside your home.
Will my heating controls work the same way with a heat pump system as they do with a gas boiler?
Modern heat pump systems are supplied with modern heating controls, so that you can set up and manage your heating and hot water exactly as you need them – to make sure that the house is warm when you’re getting up, and that there’s plenty of hot water for showers and baths when you need it.
It’s also possible to have smart heating controls for your heat pump, with wireless connectivity and a smartphone app. This means that you will be able to control your heating very accurately, using a recommended ‘set back’ temperature for optimum efficiency. Smart controls can be used to schedule times when the system will be in setback mode (for example when you’re out at work or at night-time). Scheduling of controls should be considered at design stage as your installer will be able to offer the best advice and help you set up your controls.
Do I have to get rid of my gas/LPG/oil boiler altogether if I install a heat pump?
It may seem that making the decision to install a heat pump means moving away from gas altogether. In fact, it is possible to use a heat pump alongside a gas (or LPG/oil) boiler.
This approach is a good idea for homeowners who would like to benefit from renewable energy with a heat pump, but who do not want to move away entirely from the convenience of a gas boiler. And if your home is off the gas grid, this approach is also suitable with an LPG or oil boiler.
For example, in a dual system, the heat pump could provide the heating, while the boiler produces hot water. An added advantage is that if you have a combi gas boiler, there would be no need to install a water cylinder in the home for hot water production (as there would be with a heat pump-only system).
Using a heat pump and boiler in tandem is also a useful option for homes that have a high heating demand. This could be because it’s a large house, or perhaps one that is difficult to insulate (if it’s an old building, for example). For this type of property, including a boiler in the system means that during times of peak demand, in cold weather for example, the boiler can boost the heating in your home – keeping it comfortable.
Another option to consider is that it’s possible to include solar photovoltaics (PVs) in this approach, as they can provide a proportion of the electricity for the heat pump element of system – reducing your home’s grid electricity consumption and energy costs, as well as reducing your carbon footprint further.
With the hybrid boiler/heat pump approach it’s vital to work with an installer who understands the requirements of this sort of system. They will ensure that it’s set up correctly for optimum performance.
If I change my old boiler for a new one, how much can I expect to save?
You can expect to save quite a lot of money as a new high efficiency boiler can reduce your energy bills by up to an £315* a year.
If your boiler is 10-15 years old and coming to the end of its service life or, if it is not that old but it is underperforming, you will be much better off replacing it with a high efficiency model. The last thing you want is for your boiler to have to work harder than necessary to heat your home and water and push up your heating bills. And although it may seem like a big investment you will benefit from energy savings in the long term, not to mention substantially reducing your household’s carbon emissions.
Heating alone accounts for approximately 60% of what we spend in a year on energy bills so having an efficient boiler is top priority if you want to get the best out of your system, especially in today’s world of rising energy costs.
*Estimated figures based on installing a new A-rated condensing boiler with a programmer, room thermostat and thermostatic radiator controls (TRVs) in a gas heated home from an older boiler with a programmer and room thermostat. Savings will vary depending on the size and thermal performance of your home. Source - Energy Saving Trust: March 2019.
How do I get the best boiler deal?
Where can I find out about grants for home heating?
The Government, energy suppliers and local authorities are committed to helping you save energy and reduce your impact on the environment. This help includes heating grants for homeowners - and some private renters - with low incomes. Through a government-backed scheme called the Energy Companies Obligation (ECO) you can get financial help with a gas boiler replacement and free loft and cavity wall insulation if you meet the criteria.
Previously known as the Affordable Warmth Obligation, the ECO began in December 2018 and will run until March 2022. Aimed at helping the most vulnerable customers and those living in fuel poverty, the scheme will install energy-efficiency measures in up to 900,000 eligible homes. The measures (such as new boilers and insulation) make homes cheaper to heat, as well as being more eco-friendly. All energy suppliers in the UK with more than 150,000 customers offer ECO funding.
To check if you are eligible and to find out how to claim, speak to your utilities provider or visit https://www.ofgem.gov.uk
Further information on this and other schemes available in England, Scotland, Wales and Northern Ireland can also be found on the Energy Saving Trust website which is an excellent resource for energy advice.
How much can I save by reducing my heating and water temperatures?
According to the UK’s energy regulator, Ofgem, the average household spends just over £1,200 a year on electricity and gas, and heating alone accounts for approximately 60% of this. Therefore, reducing your energy bills as much as possible while still keeping your home heated at a comfortable temperature is always desirable. And, by making a few tweaks to your daily lifestyle, it's possible to save money, for example by reducing heating and water temperatures.
Think about the room temperature that you normally set and reduce it by just 1°C – you won’t notice any difference and you can cut heating bills by up to £75 a year in a typical home, which is roughly the equivalent of a 10% reduction. Interestingly, the average temperature in a UK home is 20°C which is a full degree higher than climate change experts recommend.
You can re-set your water cylinder to a lower temperature, for example down to 60°C. (It is not advisable to set it lower than 60°C as that is the minimum temperature required to kill most pathogens in your water).
If you have thermostatic radiator valves, remember to turn them down or off in rooms that are not regular used.
How can I save money on my heating bill?
If you're wondering, "How can I save money on my heating bill?" we've put together some useful tips that can help make a noticeable difference. By using your heating system efficiently, improving your home’s insulation, and making a few small changes to your daily habits, you can significantly reduce your heating costs over time.
Start by setting your heating system to deliver the optimal temperature for your comfort, while ensuring you're only using the energy you need. There are various controls available to help with this, from simple plug-in mechanical timers to more advanced remote controls. For example, the Alpha Climatic remote control can help regulate your indoor temperatures by adjusting and limiting the flow temperature of your boiler, ensuring efficiency and comfort.
You might also want to try reducing your room temperature by just 1°C. While you may not notice a significant change in comfort, this small adjustment can save you up to £75 a year on your heating bill in an average home. If you have thermostatic radiator valves, make sure to turn them down or off in rooms that aren't in use, further cutting energy consumption.
Proper insulation can drastically reduce heat loss, particularly in areas like lofts and external walls. By keeping the warmth in and the cold out, your heating system won’t have to work as hard, helping you save money while maintaining a comfortable living environment.
For further information on this topic, please take a look at our practical heating tips.
What do I do if my radiators are cold?
One of the causes of a cold radiator is trapped air which stops warm water from circulating properly; and the tell-tale sign is that your radiator will be cold at the top and hot at the bottom. However, it is an issue you can easily fix yourself by simply bleeding your radiator, although it is a good idea to do this once a year anyway. Here is our how-to guide:
- If your radiators are cold, turn the heating off and wait for the system to cool down as the water inside radiators can be very hot
- Locate the bleed valve at the top of the radiator and put a towel or container under the valve to soak up any water that escapes
- Place your radiator bleed key in the screw and turn it anti-clockwise about a quarter of a turn, or until you hear the hissing sound of air coming out
- Let all the air escape, mopping up any water that seeps out, and tighten the valve again (but not too tightly)
- Turn your heating back on and your radiator will be warm all over, once again
Why has my hot water stopped?
This can be very stressful if it happens but before you call out a heating engineer you can check certain things that might explain why your hot water has stopped and you can take steps that could resolve the issue.
Firstly, find out if there is a localised plumbing issue in your area. If not, check if you have had a power cut which has caused the fuse box to trip, which is simple to fix. Do also check that the boiler is correctly switched on and whether it is displaying a fault code as you might be able to trouble-shoot the problem using our user manual.
If none of these steps help and a fault code is not showing you can still investigate matters a little further before calling out a qualified Gas Safe registered engineer. For example, you can check if the condensate waste pipe has frozen, whether the water pressure has dropped or if the storage cylinder temperature is set incorrectly.
We would also advise checking thoroughly around the boiler unit and pipework for any visible leaks as this scenario would require an urgent call out to a qualified Gas Safe registered engineer.
For more information visit Why has my hot water stopped?
What do the lights mean on the front of the boiler?
It can be frustrating when there are warning lights on the front of the boiler and you don’t know what they mean. That is why we have produced an online troubleshooter tool so you can instantly understand the fault type and find solutions to the problems.
To use the tool, select your boiler from the dropdown list which includes our current range and our most popular older models. You will then see a simulation of the coloured lights on the control panel for that model and a diagnosis for the type of light behaviours you are seeing ie. on, off or flashing.
In some cases, there are self-help steps that you can carry out. In other cases, a service call to a qualified Gas Safe Registered engineer may be necessary.
Remember, you can also obtain a replacement user guide for your appliance from the Document Downloads section on our website if you have misplaced your copy.
My system comes on during the night or in cold weather when not asked for?
If your heating system comes on during the night or in cold whether when not asked for, the most likely cause is that the minimum room temperature has been set too high which means the boiler will keep coming on to maintain the set temperature, especially as the general ambient temperature falls at night. Our recommendation is to set a low temperature between 8°-12°C.
You can also check the obvious things like whether the programmer or time switch have been inadvertently left on.
If you are still having problems, it is advisable to call a qualified Gas Safe registered engineer to look into the issue further.
My central heating does not work and my boiler is brand new?
When a boiler is installed on an existing central heating system, it is essential that the system is properly cleaned to remove any build-up of 'sludge' (which is generally iron oxides). The system should then be refilled and treated with a corrosion inhibitor or protector.
Failure to carry out this procedure (as specified in the Benchmark Central Heating Log Book) during installation may cause the new boiler to be contaminated by debris from the existing system. Because 'modern' boilers hold less water and are much smaller than their predecessors, they are more liable to be affected by debris in the system which can put heat exchangers, pumps or divertor valves at high risk. It is important to remember that your boiler guarantee can be deemed void if the debris from the old central heating system damages your new boiler.
What do I do when the A and B lights on the boiler are flashing alternately?
If the A and B lights on the boiler are flashing alternately this means that the system pressure is too low and you may see the pressure gauge indicating that it is below 1 bar and outside the green area.
To re-pressurise the system you will need to follow these steps:
- Find a filling loop (metal braded flexible hose) on the underside or underneath the boiler with one or two tap connections at either end of the filling loop.
- Open the tap or taps a quarter of a turn which will allow water to refill the system (which you will be able to hear as it happens). You will then see the pressure gauge rise back up into the green area between 1 and 1.5 bar pressure.
- Once the pressure gauge is in the green area, turn the taps back to the off position and the water will stop filling the system. The lights should now stop flashing and the boiler will now operate. If the lights still flash, top up the system a little more but not beyond the green area.
- If you overfill the system and the gauge is outside the green area, just bleed water from a radiator until the pressure on the gauge goes back down into the green area.
How reliable are air source heat pumps?
Due to the limited number of moving parts in a heat pump, there is minimal wear and tear, so you can expect an air source heat pump to operate reliably for ten to twenty years. As with a gas boiler, an annual service is recommended, and this can be arranged with your installer.
Heat pump systems are designed to run at lower temperatures compared to a traditional gas boiler. This means they deliver heat steadily and comfortably across the day, with no significant rise-and-fall in temperatures that can occur with gas boilers, providing a steady and reliable indoor temperature.
Why would a heat pump run constantly?
Air-to-water heat pumps operate at lower temperatures than gas boilers. While a gas boiler typically heats water to around 70°C to 80°C, heat pumps usually work within a range of 35°C to 55°C. This difference doesn't affect how warm your home will feel, but the heat pump’s lower temperatures mean that it can take longer for it to warm a space from cold quickly, which uses more energy. To maximise energy efficiency, it's more effective to run the heat pump continuously, using your controls to gently ‘set back’ temperatures at night. For instance, you could set the temperature to 20°C during the day to maintain a comfortable level of warmth, then lower it to around 17°C or 18°C at night to save energy. In the morning, the temperature can rise gently again, allowing the heat pump to maintain efficiency without causing any sudden energy spikes.
Do heat pumps work in winter?
Heat pumps work very well in winter. Air source heat pumps used in home heating systems will operate comfortably down to outdoor temperatures of -10C, much lower than we generally experience in the UK. In fact, heat pumps are used widely across northern Europe in countries such as Norway, where winter temperatures drop well below that.
One point to note is that lower outdoor temperatures affect the energy efficiency of heat pumps. On average, an air-to-water heat pump produces 4 units of heat for every 1 unit of electricity. This is known as a Coefficient of Performance (COP) of 4. In colder weather, this may fall to 2.5 units of heat for every unit of electricity: a COP of 2.5. This still compares very favourably to a traditional gas boiler which has an average COP of between 0.7 to 0.8.