Regular boilers are the simplest types of boiler and in the past have been installed in the majority of homes in the UK. They create both the hot water required for your central heating system and the hot water that comes out of your taps.
A regular boiler will always require a hot water tank
A regular boiler will always require a hot water tank and may also require a cold water header tank in the loft, depending on whether you are operating a vented or unvented hot water cylinder system.
Basically though, unvented hot water systems (also known as sealed systems) operate under mains pressure, and take advantage of a bubble of air in the cylinder or a separate expansion vessel to allow expansion of the hot water. For this reason no cold water header tank is necessary.
Vented hot water systems also require a cold water tank
Conversely, in a vented hot water system, the hot water uses the vent pipe for expansion (which connects the hot water tank and the cold water header tank); therefore it requires a cold water tank in the roof.
Advantages of regular boilers
Since regular boilers are the most basic type of boiler, they are reliable and cheaper to install than other types.
The other major benefit of having a hot water tank in your heating system is that you can pull hot water from multiple sources at the same time without any loss of pressure, since you have a large store of readily-created hot water.
In addition, most hot water tanks have electric immersion heaters associated with them so you can still get hot water even if your indirect hot water source (i.e. the hot water from the regular boiler) stops entering the hot water tank. This is obviously a benefit over combi boilers, which if broken will not be able to create any hot water at all.
Limitations of regular boilers
Since you are always required to install a hot water tank (and may also need to install a cold water tank, depending on the hot water cylinder type) when you install a regular boiler, they take up far more space than a combi boiler. This means they may not be suitable for particularly small properties.
Another issue with having a hot water tank cylinder is that as soon as you use all the hot water, then the boiler (indirect heating system) or immersion heater (direct heating system) will need to be switched on to replenish the water.
The final issue is that since you are storing hot water, there will obviously be heat lost from the hot water cylinder. Conversely combi boilers create hot water on demand, so there are no heat loss issues with these.
Condensing regular boiler
As with the other types of boiler, any open vent boiler bought today will be a condensing open vent boiler, and will capture the latent heat in the exhaust fumes of the boiler with a heat exchanger, so less fuel is used to produce the same amount of heat.
Regular boilers with solar thermal
Like system boilers, regular boilers are also compatible with solar thermal solutions. By creating hot water using the sun’s rays, you can take advantage of the RHI scheme.
Depending on its age, replacing an old boiler with a new equivalent system should result in large savings to your energy bills. This is not only a result of the condensing element of the regular boiler, but also of the technical advances that have led to increased fuel efficiency, meaning more of the fuel is converted to useful heat in the boiler.
Benefits
Many of the older boilers that will now be getting replaced are regular boilers and the process of making a like-for-like swap is relatively straightforward.
The water can be drawn through any number of taps at the same time, with no loss of pressure.
Limitations
Once the hot water in your hot water storage cylinder has been used up, you will need to wait till it heats up again.
As the water that comes to your taps will come from a storage tank, you may find that you have only one suitable outlet for mains fresh drinking water.
Regular boilers require a hot water cylinder and two cold water tanks (that need to be stored in the loft), so they take up a lot of space.
Cost
It will cost about £1600 + VAT to replace an old regular boiler with a new energy efficient regular boiler.
Installing a new boiler
Are you thinking about getting a new boiler? We have scoured the country for the best tradespeople, so that we can make sure we only recommend those we really trust.
If you would like us to find you a local installer to install a new boiler in your home, just fill in the form below and we will be in touch shortly!
A combi boiler combines a highly efficient water heater and a central heating boiler into one compact unit. As a result, the combi boiler is fast becoming the heating system of choice in new homes across the UK, comprising 50% of new boiler installations.
Combi boilers provide central heating and hot water without the need for a hot water cylinder in an airing cupboard or a cold water tank in the loft. The combi boiler is not only an ideal space-saving solution, but it also limits the amount of wasted heat when compared to traditional models, as it does not have a hot water tank.
Combi boilers and heating hot water
Combi boilers take water from the mains and then heat it as required, but are on standby when there is no water demand. Therefore hot water is available 24/7 and also just as importantly, the water is delivered at mains pressure, so no pump is required to deliver the ‘power shower’ experience (provided your home has adequate mains water pressure).
To produce the hot water that comes out of the taps, the cold mains water passes over a highly efficient heat exchanger. The heat exchanger transfers the vast majority of the heat from the burnt gas (90% or more) to the cold water, and then delivers it to the taps as required. Since combi boilers do away with the hot water tank, they are much more energy efficient, since there are no heat losses associated with stored hot water, it is simply created as needed.
On the central heating side, combi boilers pump the water round the heating system in a completely sealed system. The boiler incorporates an expansion tank internally, so there is no need for an external feed and expansion tank in the loft, which obviously saves a great deal of space.
One of the issues with a combi boiler is that they struggle to produce both hot water and central heating at the same time, so priority is given to your domestic hot water whenever a hot water tap is opened in the home. For example, if you are running a bath, during this time no hot water will be circulated through your heating system, but as soon as the bath is full, the central heating circulation will resume.
Combi boiler efficiency
Since combi boilers don’t have to store any hot water, the heat losses via the hot water tank are zero, helping save you money on your gas bills.
Most boilers installed today are condensing boilers, so if you choose a combi boiler, this will be a condensing model. These types of boilers use the heat contained within exhaust gases that would normally be released in to the atmosphere via the flue. They take advantage of heat exchangers to make the most of this latent heat, so less fuel is needed each time to heat the water, thereby further reducing your fuel costs.
The main 2 issues with combi boilers
The first issue is that since the hot water is produced at mains pressure, if the hot water is required in multiple outlets at the same time (e.g. a shower and the washing machine are running at the same time), there will be pressure drops at the different outlets. There are two solutions for this; firstly you can install a mains booster which recognises when pressure and flow are low and automatically boosts the performance of the incoming mains water. These cost in the region of £300 – £500. The second solution is to install an accumulator tank (approximately £500 – £1000 depending on the size), which is a steel vessel that stores mains water at the pressure it is supplied into the home. Air within the steel vessel (trapped in a rubber diaphragm) is compressed by the mains water. When a tap is opened, the water can rush out of the vessel to the tap faster than the mains can get into the property. The downside of the accumulator tank is that once all the water in the tank is gone, you have the same pressure issues that you would experience without it.
The other issue is that if your combi boiler breaks, you will have no hot water generating facility other than the kettle. Most hot water tanks (within the system or regular boiler systems) come equipped with an electric immersion heater, so even if the boiler breaks you can still produce hot water for showers and baths (albeit in a rather expensive way).
Final thoughts on combi boilers
In homes where hot water demand is not huge, then a combi boiler is the most effective central heating/hot water system. They are very reliable and simple to install, they save space (since they do away with cold and hot water tanks) and produce the hot water on demand as it is required in the home. As a result, in most situations we would recommend installing this type of boiler when your current boiler reaches the end of its useful life.
Benefits
The hot water is available 24/7 on demand at mains pressure, giving that ‘power shower’ effect.
Combi boilers are very compact and can sit fairly innocuously in your kitchen, or take up a small amount of space in your airing cupboard.
Combi boilers only produce hot water when it is needed, so no hot water is produced unnecessarily, which can help lower your bills.
There is no need for a hot water tank in an airing cupboard or a cold water storage tank in the loft.
Limitations
The main issue with a combi boiler is that it will struggle to cope with high demand for hot water from multiple sources at the same time, because the hot water flow rate is divided by each of the water sources.
If the combi boiler does break down for some reason, you will have no capacity to produce hot water other than the kettle.
Combi boilers are currently not compatible with solar thermal technology.
Cost
The cost of installing a brand new combi boiler in your home will obviously vary between suppliers, but prices will start from about £1800 + VAT to replace an old combi with a new energy efficient one. To replace a regular boiler or system boiler with a combi will cost an extra £500 approximately.
Companies like Heatable offer finance options, allowing you to replace your boiler from as little as £10.28 per month
Installing a new boiler
Are you thinking about getting a new boiler? If you would like us to find you a local installer to install a new boiler in your home, just fill in the form below and we will be in touch shortly!
System boilers are very similar to regular boilers; however they include some additional units in the boiler itself. There is an expansion vessel (which is required for vented hot water systems), as well as safety features like a pressure release valve which allows the boiler to release water if the pressure gets too high.
System boilers always require a hot water tank
They will always still require a hot water tank, since they create the hot water and then need to store it somewhere. However since a system boiler includes some of the components of a sealed system, such as the expansion vessel, then these will only ever be used in conjunction with an unvented hot water cylinder.
System boilers do not require a cold water tank
The great thing about a system boiler is that it means you can do away with cold water tanks altogether, which is obviously a nice space saver, although they still retain the hot water tank (unlike the combi boiler which does away with all external water tanks).
The hot water storage tank is useful because it allows hot water to be vented at numerous sources (e.g. taps and showers) within the home without losing any water pressure – this is a problem sometimes experienced with combi boilers. However by producing and storing hot water before it is needed and not at the point of demand, there is more heat loss compared to a combi boiler. As a result the hot water storage tank itself will need an insulating coat to ensure that it keeps in as much heat as possible. In addition, you will need an easily accessible space to house the tank, which means cupboard space will have to be sacrificed.
One of the major issues with a system boiler is that the hot water is limited by the size of your hot water tank. Therefore if you require a greater volume of water at any one moment than the capacity of your tank, you will need to wait until the boiler produces the hot water again (normally based on a timer system) – although this can be overridden by your heating controls if you know demand is going to be especially high.
System boilers are more complicated since they include some of the components required in an unvented system. This means that they are more expensive than regular boilers, and they will also take up more space when they are installed.
System boilers are compatible with solar thermal solutions
System boilers are also compatible with solar thermal solutions. By creating hot water using the sun, you can also take advantage of the RHI scheme.
System boiler installation
Today any system boiler you may get installed within your home would most likely be a condensing system boiler. Much like a condensing combi boiler, a condensing system boiler reuses the heat contained within exhaust gases that would normally be released into the atmosphere via the flue, which makes it more efficient. They take advantage of heat exchangers to make the most of this latent heat, so less fuel is needed each time to heat the water, thereby further reducing your fuel costs.
System boiler efficiencies
It is possible to purchase A-rated condensing system boilers, which means that they convert more than 90% of the fuel into heat. These highly energy efficient system boilers will ensure you see large reductions in your heating bills – potentially over £300, depending on the boiler that you are replacing.
Benefits
A newly installed condensing system boiler will result in large savings on your utility bills, especially if replacing an old boiler.
A system boiler allows hot water to be delivered to many sources (e.g. taps and showers) at the same time without loss of performance.
There is no need to have a cold-water feeder tank in your loft, as the cold water enters the boiler from the mains, leaving you with more loft space.
Limitations
System boilers require a hot water tank to be housed somewhere in the home, so it takes up more space.
System boilers are more expensive to buy initially than combi boilers, however they have better reliability.
Less efficient when heating the hot water tank as water is not heated and used at the point of demand.
Cost
Prices start from about £2000 + VAT to replace an old system boiler with a new system boiler. Replacing the hot water tank and other piping will obviously greatly increase the overall cost of your heating system.
Installing a new boiler
Are you thinking about getting a new boiler? We have scoured the country for the best tradespeople, so that we can make sure we only recommend those we really trust.
If you would like us to find you a local installer to install a new boiler in your home, just fill in the form below and we will be in touch shortly!
Underfloor Heating
Heating
What is underfloor heating?
Underfloor heating (also known as radiant heating) has been in operation for many thousands of years. Roman Britons used hypocausts, which involved suspended floors under which fires were lit, which then heated the floor and in turn heated the baths or rooms. A network of small pipes was used to run hot air from a central furnace and heat up the building. This created a warm air convection which heated up the main living space.
Things have moved on slightly since, but radiant heating is a great economical way to heat many areas of the home. There are now two preferred methods of underfloor heating for the home: electric under floor heating systems or hot water flowing in pipes just underneath the floor surface, known as hydronic systems.
Read on to find out about the different types of underfloor heating system.
Types of underfloor heating system
Modern underfloor heating systems use either electrical resistance elements (‘electric systems’) or fluid flowing in pipes (‘hydronic systems’ – see ground source heat pumps) to heat the floor. Either type can be installed as the primary, whole-building heating system or as localised floor heating for thermal comfort in a particular room.
Electric underfloor heating systems
Electric underfloor heating systems work by using electrical resistance elements. When the system is switched on, the system gets warm, heating the wooden, tiled or carpeted floors above it. The floor then acts as a large radiator; hence underfloor heating is sometimes known as radiant heating.
This form of underfloor heating is very easy to install, and also it is very thin (in comparison to the Hydronic systems), so you will not lose any height from your rooms if you retrofit this technology within your home. Also the electrical resistance elements that make up the system run at 100% efficiency, so all the electricity that runs through them is turned into heat. The electric system you install will depend on the size of the room and type of flooring, but options include heating mats (rolled out to cover large areas), electric cable systems, or loose fit wiring flexible enough to fill more awkward spaces.
Most electric underfloor heating systems are straightforward to install, assuming that you are reasonably competent at DIY. However all electric heating systems installed in the home must be signed off by a competent electrician under the 2005 Part P building regulations.
Hydronic underfloor heating systems
Hydronic underfloor heating systems rely on hot water heated within a boiler system (or via a Ground Source Heat Pump or an Air Source Heat Pump) to provide the heat to warm the floor and the associated room. The hot water flows through pipes situated beneath the floor level which then heat the floor. As the heat is being given off by a larger area (the entire floorspace), it does not need to be as hot as the water flowing through radiators, as it is more evenly distributed within the room.
Unlike the electrical underfloor heating systems, hydronic systems will cause you to lose some height of the room if they are retrofitted (as there are pipes that carry liquid – which have a thicker profile than wires). This is the ideal technology to put in at the same time as replacing an existing floor though (please also fit Floor Insulation when you do this). In addition, unlike the electric systems, we suggest that you bring in a certified underfloor heating engineer to install this type of system.
One of the major advantages of hydronic underfloor heating systems is that they can also be used to cool a room in the summer. Unlike the electric systems, if you pump very cold water through the pipes, it will cool the floor and work in the exact reverse process, cooling the room.
Megaflo unvented hot water systems
Heating
We are seeing more and more people installing Megaflo heating systems in their homes, but what are they and why are they becoming so popular? Well, a Megaflo is essentially a brand of hot water tank – but the major difference is how they are plumbed in.
Older, traditional heat only systems have cold water expansion tanks up in the roof, and it is the height of this cold water tank above the hot water cylinder that generates the pressure that delivers the hot water to the taps. For taps on the lower floors, this tends to work perfectly, but for bathrooms upstairs the pressure is often not great and so you get issues like weak showers or baths that take an age to fill up. In many cases, this is sorted by installing a pump that drives the water from the hot water tank to the required faucet, but installing a Megaflo does away with all these issues!
Megaflo – an unvented hot water cylinder
Megaflo cylinders form what is known as an unvented system – this is pressurised to mains water pressure, ensuring a strong flow of hot water when you turn a tap on in the home, regardless of where it is located. The actual pressure in this type of hot water cylinder is normally about 3 bar, which is equivalent to a cold water tank being 30m above the tap for a heat-only system. The cold water is fed into the bottom of the tank at mains pressure. This forces the hot water out at the top and this then travels to the tap. This means that you have great pressure all the time, so gone are the days of the dreaded dripping shower!
Since the volume of water increases as it gets heated, all unvented systems require some sort of expansion vessel to absorb this increased volume. The nice thing about the Megaflo models is that they contain an enclosed air bubble within the tank itself, which acts as the expansion vessel so you don’t require an external one. It’s worth mentioning, though, that over time the air bubble can be absorbed into the water; this can be recharged as part of an annual boiler service.
Like other heating systems, the hot water within the Megaflo can be produced by immersion units (so heated with electricity), boilers or even solar thermal. If you buy a twin-coil unit, you can feed the tank with two sources of hot water: a boiler plus solar thermal, for example.
Although there are lots of hot water tanks suitable for use within unvented systems, the Megaflo is the market leader in the UK. This is partly because the brand, but the performance of these cylinders really is very good. They are tested to withstand 15 bar of pressure, so you can be sure they are up to the job of operating at these higher pressures (compared to conventional heat-only systems).
Megaflo cylinders also have great safety features incorporated into them. This includes thermostatic controls that prevent the water in the cylinder ever being heated above 100 degrees centigrade, as well as expansion release valves that allow expansion to take place if the cylinder doesn’t perform correctly. There is also a temperature and pressure release valve situated on top of the tank, which vents water if it hits unsafe temperature levels. Megaflo cylinders also include a 60mm-thick layer of polyurethane foam to insulate them. This ensures that once the hot water is created it stays warm for longer, minimising the need to reheat the water.
So having looked at the advantages of the Megaflo cylinders, what are the issues with them? Well, not many performance-wise, however they are significantly more expensive than other unvented cylinders.
Unvented systems are also generally more expensive to install compared to heat-only boilers. They must be installed by a competent and qualified G3 engineer; this is a legal requirement in the UK and all installations must be certified and registered with the local council. This means that your average plumber/heating engineer will not actually be allowed to install one in your home.
The other issue – and this is not just Megaflo, but all unvented systems – is the high pressures involved. Obviously if everything is working correctly then the performance will be great, but all pipework needs to be able to withstand the higher pressures!
The performance of the Megaflo cylinders makes them extremely popular – the hot water is delivered to every tap at mains pressure and the tanks themselves are well insulated, ensuring they operate very efficiently – but be prepared to pay more to install one of these in your home!
Installing a new Megaflo
Are you interested in installing a Megaflo? We have scoured the country for the best installers, so that we can make sure we only recommend those we really trust.
Combined heat and power (CHP) boilers produce both heat and electricity in one single process. This process is sometimes referred to as cogeneration and the technology that supports it has been around since the 1970s, but has mainly been confined to industry and large dwellings such as hospitals and sports centres.
As the price of fuel has increased over the last few years, it now makes economic sense to bring CHP technology into the domestic setting.
A micro-CHP boiler is defined in the EU Act on Cogeneration as a domestic unit that is limited to 50kW of capacity.
The different types of CHP boiler
There are three types of micro-CHP boiler:
The Stirling engine CHP boiler
The Stirling engine CHP boiler is a type of external combustion engine, where the combustion engine is heated when the boiler is fired up to produce the hot water. This heats up the fully enclosed working gas within the Stirling engine, causing it to expand. The expansion of the working gas forces a piston to turn up and down between a copper coil, generating an electrical current, which can then be used in the home. The working gas usually used in a Stirling engine is helium, due to its strong heat transfer properties.
The main limitation of this type of boiler is that it only produces electricity when you have the central heating on, so despite being a very efficient type of boiler, it does not produce an abundance of electricity. A key advantage is that the combustion process involved in a Stirling Engine CHP boiler is much quieter and more efficient than internal combustion engines.
The internal engine CHP boiler
This type of CHP boiler is commonly used in large dwellings such as hospitals. It involves using a fuel source to drive a turbine, which is connected to the electricity generator. The waste heat from this combustion process is captured to produce hot water for the space heating and warm water. This is the most common form of CHP boiler found to date. However the process is noisy and you have far less control over the hot water generated, so fuel cell and the Stirling engine CHP boilers are often preferred.
Fuel cell CHP boiler
Fuel cell CHP boilers use fuel cells which convert fuel and air directly into power and heat through a quiet, efficient, solid-state electro-chemical reaction. A video demonstration of how a fuel cell CHP boiler operates in the home can be found on the Ceres Power website.
Fuel cells generate power significantly more efficiently than internal combustion and Stirling engine CHP boilers. This is because fuel cell CHPs convert chemical energy directly to an electrical current, maximising their efficiency.
This type of CHP boiler is still in development so is not yet commercially available on a wide scale.
How CHP boilers work in the house
A home would typically use a boiler to meet its heating and hot water needs only, and then source its electricity from the grid. Central generation wastes a significant proportion of the energy it creates, through heat losses in the power station and in the transmission and distribution network.
Micro-CHP boilers avoid these losses, and capture the heat for use within the home. This efficiency can save the consumer around 25% of total energy costs (around £600 off your bill if you have a typical 3-bed semi-detached house), and reduce each home’s CO2 emissions by up to 1.5 tonnes per annum. Micro-CHP boilers are designed to generate all of the heating and hot water and a significant percentage of the electricity needed by a typical UK home.
The CHP boiler can use a variety of fuel options including the gas that is supplied by your current provider, but also hydrogen, LPG & biofuels. Even during the summer when the home’s central heating system is turned off, the heat produced by the micro-CHP boilers when generating electricity can be stored in a back-up hot water cylinder and then used for domestic hot water. Therefore the micro-CHP boilers are capable of operating all year round, maximising energy bill savings 365 days a year.
Micro-CHP boilers are designed to one day replace your normal condensed boiler, using the same types of connections; they also have similar installation and maintenance requirements. A micro-CHP boiler only requires one connection to the electricity network in the house and it’s ready to go!
Industry development
Micro-CHP boilers are an example of a microgeneration product for the home. The UK Government has estimated that microgeneration products (such as micro-CHP boilers) have the potential to supply over 30% of the country’s total electricity needs and help meet its international environmental obligations, such as the 2020 EU carbon emission reduction targets.Owning a micro-CHP boiler is one step in the right direction. Full costs in the UK of a micro-CHP boiler including installation are yet to be made fully transparent; however incremental cost estimated in the region of £2,500 to £3,500 versus a condensing boiler, therefore a full installation is then estimated at between £5,000 to £7,000.
Research commissioned by the Government has shown that micro-CHP boilers have the potential to become the micro-generation ‘system of choice’, replacing the condensing boiler, which is the standard system in most UK homes today. Commercial experience has also shown that realising the benefits early pays off the most over the long-term.
Currently only the Stirling engine-type micro-CHP boilers have been made available on the domestic market. For example the Baxi Ecogen product is one of the few available micro-CHP boilers that is commercially viable and available for the home. By the middle-end of this decade, the expectation is that fuel cell models such as the Baxi Gamma 1.0 will be fully available to the UK consumers.
When fuel cell micro-CHP technology is commercially available, the consumer should see the price of Stirling engine models fall. In addition with the competition in the fuel cell space (Baxi, Ceres Power, etc), this should also make those models commercially competitive. Current evidence suggests that the take-up in UK homes has only been limited, with a lower number of Micro-CHP boilers currently installed in the UK than expected by the government – as opposed to Denmark and Germany where the technology has been more widely adopted.
CHP Boiler Technology Summary
The following list is a quick summary of the CHP boiler features:
Delivers central heating, hot water and electricity
Simple to install, replacing an existing gas boiler
Easy to use with automatic operation
Can use the same gas supplied by British Gas, NPower and other gas providers
Lifespan of the fuel cell boiler, yet to be determined (but typically 10-12 years)
Remember micro-CHP boilers are efficient because they generate heat and electricity in one place. They will save you money and help the environment. Currently only the sterling engine type of CHP boilers are available to the residential market (internal engine CHP boilers are available for large properties), but in a few years’ time fuel cell micro-CHPs will also be available. Micro-CHP boilers are a strategic domestic technology for micro-generation that will help homes with their energy needs, but also help the UK (and other EU countries) meet external carbon emission targets.
Benefits
CHP boilers are more environmentally friendly, reducing a typical home’s CO2 (carbon dioxide) emissions by up to 1.5 tonnes per annum in the UK.
Mounting a CHP boiler can help you reduce your energy costs by 25% or more.
Most CHP boiler manufacturers have partner agreements with the major suppliers (e.g. with British Gas) who provide installation services. Potential customers should check first with the manufacturer if you would like to arrange their own private installation.
Limitations
The payback on the premium, which is the additional cost of a CHP boiler versus a condensing boiler, can pay for itself over the product’s lifetime. Note: Research in this area is not extensive as there are currently only a few commercialised producers of domestic CHP boilers.
Cost
The full cost of installing a CHP boiler is somewhere between £5,000 to £7,000, depending on the type of installation and home specification, which is quite a big investment for a typical household.
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