Micro CHP Boilers

So. You’ve just upgraded your old central heating boiler to a brand new, highly efficient condensing combi boiler and you’re feeling pretty good about it. It came with an excellent warranty and service package and you’ve been advised that the central heating, the remote access control system and the sophisticated programming features are all examples of the latest technology.

Then your neighbour gleefully informs you that he is planning to install a micro CHP system. This naturally deflates your buoyant demeanour and sends you scurrying to the internet to see what advantages your neighbour might be obtaining.

Combined heat and power (CHP) boilers have been around since the 1970s. Due to their size, weight, cost and operating noise, they have generally only been suitable for industrial and large communal facilities. They have been installed to primarily generate electricity, usually by internal combustion engines and dynamos, with the secondary heat by-product being utilised for central heating purposes.

In recent years, technological advances, spurred on by rising energy costs, have enabled the concepts of the commercial CHP boilers to be adapted for domestic operation. These new compact and vastly superior devices are referred to as micro CHP boilers.

Although much of the technology is still in the developmental field, some micro CHP boilers are available on the market.

Current models are similar in size to a large domestic condensing boiler and are wall mounted. They are also plumbed into the central heating system in much the same way. They do require installation by a Gas Safe engineer and a Micro-generation Certification Scheme (MCS) approved installer. What makes domestic micro CHP boilers special is that in producing heat for domestic hot water and central heating, they also use the heat to generate electricity for the home. Any surplus electricity is then directed back into the grid. The boiler owner receives a payment for the electricity produced for domestic use and also a payment for surplus electricity fed back into the grid.

At first sight, it can all appear very attractive, and no doubt, the neighbour has seen this as an opportunity too good to miss.

There can be no doubt that electricity produced from a remote power station is a dirty, inefficient fuel. Only about 30% of the energy from the source fuel is actually available to the consumer. The rest is lost in production and supply.

Being able to produce electricity at the point of usage has great advantages and can provide energy efficiency levels in excess of 90%.

The vast majority of micro CHP models currently available employ the actions of a Stirling engine to generate electricity. Stirling engines are classed as external combustion engines. They utilise the properties of internal chambers filled with a gas, usually helium. This gas is responsive to areas of hot and cold within the chambers. Applying heat to the gas causes alternating pressures as it moves to a colder area, and vice-versa. This movement operates a displacer and piston. The piston moves up and down inside a copper coil at around fifty times a second to produce electricity, which is fed into the domestic electrical supply.

The Stirling engine generates about 1 kW of electricity as it operates.

Because these boilers use gas in a very controlled and efficient manner, the general idea is that the Stirling engine should operate continuously using small amounts of gas to efficiently generate electricity, and supplement the domestic central heating and hot water supply, with a boost heating facility to raise the hot water system to demand levels.

Every electrical kW produced and used by domestic consumption receives a payment from the energy supplier. This acts as an inducement to produce electricity and as a payment for not using the supplier’s inefficient electricity source. On top of that, any surplus electricity is directed back into the grid and receives a FIT payment (the Feed In Tariff) from the provider for each kW produced. The micro CHP boiler must be installed correctly by an MCS installer to qualify.

So where are the pitfalls?

The major drawback is the cost. Currently, purchase and installation costs are in excess of £5000. The life expectancy of models on the market is around ten years. With gas and electricity fuel prices so volatile, it becomes difficult trying to assess whether, or when, the capital expenditure and the interest payments on any financial assistance packages would justify installation.

There have been calls for a substantial increase in the FIT to make installation of micro CHP boilers more attractive, but as yet, there has been no movement on that proposal. As such, any financial advantages are likely to be very modest over the long term.

Perhaps the main obstacle for installing current micro CHP boilers is the situation in a potential buyer’s home.

Householders have responded favourably to Government incentives and environmental concerns over recent years. They have improved insulation and many have installed a variety of heat saving devices. Some have adopted technologies that supplement heat requirements with heat recovered through accumulators.

The amount of gas that is required to heat a well-adapted home is now significantly less than in previous times.

However, demand for electricity is increasing. Households now require constant electricity, not constant heat.

The 1 kW electrical output of a micro CHP boiler with the current FIT and kW subsidy does not make the installation of the boiler a realistic proposal at the moment.

The future for micro CHP boilers is, though, looking good. Manufacturers are developing superior alternatives to Stirling engines. Ceres are developing fuel cell technologies that will revolutionise domestic heat and electrical production. Within these fuel cells, heat and electricity can be generated without combustion removing all the problems associated with it.

Hydrogen cells are being developed to utilise the energy produced by micro CHP boilers and other green energy generating technologies. Hydrogen can be produced by surplus electrical activity and then used to generate electricity again at peak demand.

These green and clean modifications incorporated into, or complimenting micro CHP systems will make installation more of an attractive proposition in the future. The electrical kW output produced is much greater. Already the major energy companies are voicing disquiet about the possibility and implications of millions of micro energy producers feeding surplus energy back into the grid. And with some justification!

Perhaps lots of micro energy producers supplying a local network might be the answer to the ailing, aging and costly grid network, in addition to the public’s growing disquiet about the energy company’s extortionate energy generating profits.

In the meantime, compliment your neighbour for considering becoming a torchbearer and protagonist of nascent technologies.


Notification of Gas Work


Imagine the scenario. You’ve had your property on the market for a considerable period. Now you have finally found a buyer and also the house of your dreams. Then your solicitor informs you that there is a problem with the new property’s gas installations in respect of Local Authority notification and the Building Regulations.

The Building Regulations require that in England, Wales and Guernsey, certain controlled building services have a mandatory requirement of notification to the relevant Local Authority. The controlled services include the installation of gas appliances, namely, boilers, water heaters, warm air heaters, gas fires, flue dependent cookers and heating systems.

In Northern Ireland and Scotland, there is no mandatory notification requirement, however, homeowners can obtain a Declaration of Safety Certificate that can reassure possible purchasers that a competent person has installed a gas appliance.

The term ‘competent person’ is key to obtaining a Building Regulation Compliance Certificate. Although it is quite possible to seek approval for gas installations from the Local Authority directly, the process of inspection and authorisation required to comply with certification can prove costly.

An installer registered with a Competent Person Scheme is qualified to carry out specific types of work in accordance with Building Regulations, and will usually deal with all building control issues on your behalf. A registered competent person is authorised to self-certify certain completed gas installations. This has the advantage of significantly reducing the cost of obtaining your own Local Authority notification.

For gas work notification and competent persons, Gas Safe registered engineers are the only persons legally permitted to install gas appliances and consequently issue self-certification to comply with the Local Authority requirements under the Building Regulations.

Although Gas Safe registered engineers are professionally obliged to notify the Local Authority, compliance with Building Regulations requirements is ultimately the responsibility of the property owners. As non-compliance can incur considerable inconvenience and a hefty fine of up to £5000, it is in the homeowner’s interest to ensure that a Building Regulation Compliance Certificate is issued by the Local Authority. The certificate relates solely to the property and should be kept safe. A Gas Safe engineer should notify the Local Authority within thirty working days after completion of the work.

Where a Gas Safe registered engineer fails to notify the Local Authority in accordance with requirements, the homeowner should complain to Gas Safe. They will issue instructions to the registered engineer to submit the notification, but they have no powers of enforcement.

All too often property owners are unaware of statutory requirements and are easy prey for rogue gas fitters. It is an inevitable fact that a Competent Person Registration Scheme, particularly the one operated by Gas Safe, can deter unscrupulous engineers from alerting the register to completed gas installations. This is because Gas Safe, operating as a central database of completed installations requiring Local Authority Buildings Regulations Compliance Certificates attracts the attention of HMRC.  This means that  some engineers and businesses can be investigated on suspicion of  tax evasion.

Of course, any database of information similar to that used by the operators, Capita PLC in respect of Gas Safe, is bound to be of interest to the big companies, particularly those who manufacture gas appliances and the energy providers. Notifications lodged with the details of an engineer’s customers and their addresses are quite valuable. Some engineers feel that passing their customer’s information back to Gas Safe might be a little unethical.

Such issues aside, although compliance with Local Authority and Building Regulation requirements can seem bureaucratic, there can be no doubt that stringent regulations are in the customer and consumer’s best interests. Where gas safety is the priority, professional and competent installations are a necessity in avoiding the consequences of poor, unqualified and dangerous workmanship. Too often the drive to cut costs in a very competitive market results in corner cutting procedures that lead to extensive problems at a later date.

Where a problem with Building Regulations relating to gas installations becomes identified during a property sale, the issues can be resolved. The absence of a Buildings Regulation Compliance Certificate does not necessarily mean that the Local Authority has not received notification. A request can be made to the Local Authority to confirm compliance and a replacement certificate can be purchased.

Where no notification exists and the installation contravenes Local Authority and Building Regulation requirements, it is the responsibility of the property owner to remedy the situation. Depending on the nature of the installation it is possible to get a Gas Safe registered engineer to re-commission an appliance and obtain the necessary documentation. Whether the Local Authority pursues the matter further in respect of the previous non-compliance is a matter of their discretion.

Alternatively, the property purchaser may apply to have appliances checked over by a Gas Safe registered engineer to ensure that they are safe and with no at risk issues. They can also obtain a gas safety inspection certificate.

The lack of any required Buildings Regulation documents or failures of notification can cause considerable delays in exchanging contracts during property sale procedures. Costs can escalate when seeking confirmation and the property value can be reduced in favour of the purchaser to accommodate any remedial requirements.

Boiler Fittings and Mountings

The fittings and mountings for domestic boilers are usually dedicated to specific boiler types and individual manufacturer’s boiler models, and as such are produced by the manufacturer and provided with the boiler and the installation package.

Domestic boilers include oil, wood, coal and electric fuel sources and a wide range of different models are available to choose from when considering which type of heating boiler is to be installed.

Coal or wood-fired back boilers are often found in old properties and it is very simple to remove a damaged boiler and plumb in a new one. Fittings are generally plumbing standard.

Oil fired boilers require an external large capacity oil storage tank, and the are usually floor standing. Plumbing and fitting components are generally plumbing standard, however, the boilers are often heavy and large. There are wall mounted oil fired boilers available and these are normally installed externally.

Both these types of boilers can be installed by any person with an adequate knowledge of plumbing and heating techniques, although where electrical installations are complimentary to the system, these should be installed by competent electricians.

Electric heating boilers are usually positioned discretely out of sight, although some which provide only domestic hot water on demand can be wall mounted at the point of use. The mountings should be secure, but as these units are quite light, they do not require the same weight-bearing considerations as those of complex gas condensing boilers.

Because combustion is not a process utilised by electric boilers, neither a flue nor a ventilation requirement is necessary. These boilers can run central heating systems but are considerably more expensive to operate than their gas-burning alternatives. These boilers do require basic plumbing installation techniques.

Electric boilers do not require local authority notification and can be installed by a competent electrician.

Gas boilers are a different matter. Most new gas boilers are wall mounted condensing boilers and although they can be located discretely, they require careful consideration when choosing a location.

For the purpose of flue ventilation, they require an external access point and are usually installed on the inside of an external wall.

The location of the exhaust gas flue is subject to restrictions to prevent nuisance to neighbours and to prevent any possibility of flue gasses re-entering the building. It is possible to locate a boiler externally, subject to the manufacturer’s recommendations.

The boiler installation must comply with BS 5410 and the Building Regulations Part 2. 1997.

From 1 April 2009, it is a legal requirement that gas boilers can only be fitted by a ‘Gas Safe’ registered installer.

The wall upon which the boiler is to be mounted must be surface flat and capable of supporting the weight of the appliance when it is operating full of water. This can be in excess of 100 kg with larger boilers.

The boiler will come with a dedicated template to allow markings of mounting bracket locations to be transferred to the wall. It is essential to ensure that the template is level before proceeding to mark or drill and that the position chosen allows extra area above the boiler for the installation of the flue. The template may also provide markings for a gas and water connection plate. These should also be transferred to the wall. The bracket, when fixed, must take account of the boilers clearance requirements as stated in the installation instructions.

The bracket must be attached to the wall with anchor bolts that are suitable for the wall’s construction material and the weight of the boiler.

Once the gas and water connection plate has been attached to the wall, the water and gas can be connected to the plate. The connections are standard starting left to right: heating supply, domestic hot water, gas, cold water and heating return. The manufacturer’s instructions will clearly indicate which service is required to each connection point.

When attaching the boiler to the gas supply, the correct fittings must be installed to prevent any unwanted drop in gas pressure.

A connection plate allows other trades to complete installation procedures prior to the hanging of the boiler onto the mounting bracket and final connection of the boiler.

In the absence of a connection plate, the plumbing can be made straight to the boiler directly.

Plumbing and pipe-work will be dependent on the system the boiler is designed to supply.

It is also a wise precaution to install service valves to the pipe-work to aid future service and maintenance procedures.

A drain, or the access to one, is also a requirement to accommodate pressure release valves and condensate drainage.

The positioning and installation of flue gas and air intake pipework should be in accordance with manufacturer’s instructions. Some of the components for this may not be included in the boiler installation kit. This is because variations in the flue gas assembly are dependent upon legal requirements, location, and circumstances and are generally constructed to individual requirement.

The electronics are usually the final connections to be made to the boiler. These will include room thermostats and system programmers. Other sensors may require additional connections, including mains water supply sensors and low water cut-off sensors.

Finally, the boiler can be attached to the mains electricity supply which will power all the electrical components and the boiler can be commissioned.

The connections of the electronic components and the connection to the mains supply require the skills of a competent electrician.

Noisy Central Heating Causes and Solutions

Noisy central heating systems can be a considerable irritation for households. They often seem to manifest following the installation of a new boiler or at the onset of winter when the central heating system is turned back on. Sometimes, identifying these noises and locating the source can be difficult. The noises may travel around the building and be heard some distance from the source.

Where a new boiler or a new central heating system has been installed, noises are often the sign of poor installations. Sometimes, if a new boiler makes unexpected noises, it can be due to an insufficient water supply. In all probability, the water inlet pipe may be of a too narrow diameter to accommodate the boiler requirements. Replacing this pipe will, in most cases, rectify the problem.

Running a combi boiler at too high pressure will cause boiler noise. The system cold pressure should be around 1 bar. Working pressure should register between 1.5 and 2 bars. The manufacturer’s operating instructions will indicate the correct operating pressure and how to adjust it.

Although prior to installing a combi boiler, water pressure and flow rates should be checked, it is not always the case that they are. Sometimes, the mains water pressure is inadequate, particularly where a combi boiler is installed to replace an existing F and E system. This will result in unacceptable noises being emitted when the boiler operates. This problem can be satisfactorily addressed, but specialist-plumbing advice will need to be obtained.

In some cases, inadequate water supply is caused by restriction of the mains supply pipe due to encrustations of mineral deposits. It may be necessary to replace the mains supply pipes to address this problem. The water provider may be responsible for some of this work if it lies beyond the property boundary.

Conversely, high mains water pressure can cause noisy operation of a combi boiler and cause water hammer in other parts of the plumbing system. Sometimes it is possible to reduce mains water pressure by adjusting the mains water stopcock.  This should be carried whilst monitoring a running cold-water tap. By observing the water flow at the tap, a reasonable assessment can be made of how much to turn off the supply at the stopcock. Alternatively, fitting a pressure-regulating valve to the mains supply at a position after the stopcock will effectively control high water pressure. This valve can be adjusted to provide the recommended pressure of water flow into a combi boiler.

Shortage of water supply to a boiler will certainly produce noise. Most boilers will not operate when water is not available. On an F and E system, an empty header tank may be caused by a blocked or damaged ball valve or an interruption to the mains water supply. Frozen pipes and air locks can also cause interruption to water supplies. However, a return of hot water into the F and E tank from the expansion pipe may indicate a serious boiler malfunction and expert assistance should be sought.

Kettling in a boiler can be caused by a build up of lime scale on the heat exchanger plates. Although lime scale deposits can be reduced by inhibitor on the central heating side of the heat exchanger plates, the boiler side plates will need servicing by a qualified heating engineer.

Where a new central heating system has been installed, knocking noises can be caused by pipe-work that has not been securely supported. However, if the pipe-work has been installed without regard for hot water pipe expansion, the same noises can occur. The problem can be compounded where pipes have been installed in a restricted area where they may rub against each other when expanding. Clip fastening unsupported pipes and inserting foam spacing between pipes in close proximity will remedy these noise-creating problems.

Expansion of pipes located in grooves in floor joists can cause noises, which become amplified through the building. These noises can be eliminated by insulating the pipes passing through grooved joists. It is not a good idea to increase the groove size to accommodate insulation. This may weaken the joist. Applying foam insulation where conventional insulation materials cannot be used may help to reduce the noise.

Noises that are located around the central heating water pump may be caused by sediment eroding the pump mechanism or by pump speeds being set too high. Pump speeds can be adjusted by operating a control device usually located on the front of the pump. Pumps damaged by erosion will need maintenance or replacement.

Air trapped in the system, particularly in radiators, will cause gurgling and popping noises due to expansion and contraction. These noises can be particularly loud. Bleeding the radiators to release trapped air usually solves the problem. Turn the boiler off before bleeding radiator valves. Because water carries around 2% air by volume, air will continually build up in central heating systems, and regular radiator bleeding may be required to prevent noisy operation and maintain system efficiency.

Sludge build up and lime scale deposits can all make a central heating system operate noisily. A 1.6 mm layer of scale will reduce heating efficiency by up to 12%. Power flushing the system regularly will help to remove sludge and debris and the addition of inhibitor will reduce deposit formation.

Draining the central heating system and refilling with the inclusion of a proprietary scale and deposit remover will help to clean an already scaled system. The de-scaler should be allowed to circulate throughout the system for a couple of weeks. Hopefully, the noise from the system will reduce during this time. The system can then drained again and refilled with water and inhibitor. Prior to using de-scalers, boiler warranty conditions should be examined for exclusions.

In general, competent installation procedures and good maintenance practices will reduce the chances of noisy boiler and central heating operation. Poor maintenance will result in sub optimal efficiency and increased running costs. Build up of deposits will shorten pump and boiler operating lives and result in expensive heating engineer call out costs.


New Boiler Installation Problems

Having a new boiler installed can make a huge difference in operating efficiency and a considerable reduction in energy costs. As nearly all new domestic boiler installations are now required to be condensing appliances by law, most homeowners are delighted by the benefits. New condensing boilers are lean operators when correctly installed and coupled to sophisticated modern programmers and thermostats.

Over the past few years there have been a number of initiatives introduced to attract homeowners into scrapping their old, inefficient boilers. Grants, free installations and competitive finance packages, have proved to be quite attractive to homeowners. Heating engineers and plumbers have also seized the opportunity to cash in on the great energy efficiency spend.

But what happens when things go wrong?

Most new gas boiler installations are carried out by very experienced gas engineers who have many years of boiler working experience under their belts. Coupled with this they are required by law to be registered with Gas Safe. In order for them to be registered, they must undergo rigorous training and assessment procedures designed to establish competence and encourage safe installation practices and procedures.

It is against the law for any person who is not competent to undertake work on a gas appliance.

However, being Gas Safe registered does not necessarily of itself mean that a gas engineer has the interests of the homeowner at heart. In what can be a very competitive market, with the major energy companies muscling in with the ability to negotiate advantageous bulk purchasing deals from boiler manufacturers, cutting corners to save costs can become an issue.

For some homeowners, the leaflet pushed through the letterbox offering a deal too good to miss on a new boiler installation can be the beginning of an unexpected nightmare.

The quoted installation costs might seem attractive, but the boilers are often of unreliable eastern European manufacture and the finance associated with the packages can have hidden costs and unfavourable interest rates attached.

The danger with these operatives, quite apart from the questionability of the safety and suitability of the installations, is the difficulty of obtaining redress if things go wrong.

Warranties may turn out to be void due to poor installation, finance deals may have variable interest rates and contacting the installer may become problematic. Finance agreements can be sold on to other brokers and financial houses, and some installers have a bad habit of periodically ceasing trading as one company and starting up again as another.

Even with the better-known national boiler installation businesses, things can sometimes go wrong. New boilers can be installed that have inherent faults that, if not rectified, develop quickly into customer satisfaction issues. On occasions, and despite considerable investigation, the cause of the fault is never pinpointed. Manufactures and installers struggle to remedy the situation with neither keen to accept liability.

With a myriad of clauses and exemptions built into warranties it can be difficult to know whether a boiler fails to operate correctly because of an existing fault, or whether the fault results from damage caused by poor plumbing, or problems with central heating components.

Conversely, it can be a case that an incorrectly sized or poorly installed boiler causes considerable damage to a central heating system and to the occupant’s furnishings.

So, when things go wrong, where does the boiler purchaser stand?

Well, where a boiler has been purchased from the installer or the installer’s company, then they are responsible for putting right any installation problems that are obvious immediately, or within a few days of installation. They are also required to replace a faulty boiler should the need arise. It is their responsibility to take the matter further and seek their own redress from the boiler manufacturer. This matter is covered under the Sale of Goods Act 1982.

Where the boiler has been independently purchased by the homeowner, then the homeowner must contact the boiler manufacturer before engaging a gas engineer to investigate the problem. It is the boiler manufacturer’s responsibility to quickly remedy the situation. The homeowners could invalidate any obligations on the part of the manufacturer if they proceed to try to repair a fault independently.

Where householders have unwittingly entered into an installation contract with an un-reputable company, they may find that seeking redress can be quite unproductive. It is often advantageous to have paid for installation on a credit card. This can sometimes provide insurance cover when goods are not of a serviceable nature. In these cases, the purchaser should contact the credit card company.

The small claims court can be a final tool in the armoury of the homeowner when new boiler installation issues remain unresolved. The mere threat of legal action can make slow to respond companies jump into action. Although engaging a solicitor can be helpful, there are suitable templates for letter formats available on-line. It is quite easy for homeowners to proceed through the small claims process themselves.

Perhaps the best way to minimise the chances of becoming embroiled in issues around new boiler installation problems is to carefully consider any installation packages and procedures.

Always buy products and services from reputable companies.

Ensure that any gas engineer is Gas Safe registered and authorised to undertake the specific tasks required. The competence in various areas of gas engineering work will be stated on the engineer’s photo ID card. Always insist on seeing this prior to engaging an engineer’s services. Always make sure that the photo on the card corresponds with the engineer carrying out the gas work.

Gas Safe registered does not necessarily mean that the gas engineer is good at his job. Try to obtain recommendations from previous customers.

No matter how time consuming, always read the small print on warranties, finance deals and insurance documents carefully. Ensure that you fully understand any technicalities prior to signing and entering into an agreement. Such agreements are generally legally binding and rarely in the customers best interest.

Where possible, and if the card provides cover, try to use a credit card to pay for goods and services.

Know your rights, and limitations. Be confident and assertive when dealing with new boiler installation problems and issues. You have the right to seek an effective resolution to problems within a reasonable time-scale, and the right to compensation for legitimate inconvenience.

If you suspect that a Gas Safe registered engineer’s work is suspect, you can ask for a free inspection of the work by Gas Safe inspectors.

Where problems occur following a new boiler installation, reputable companies will usually put things right quickly with very little inconvenience. Most issues can be resolved amicably. A good company’s reputation can rest on customer satisfaction.

As in all purchases, cheap is not necessarily best and too good to miss offers rarely are.

Combi in the Loft

Condensing combi boilers are, by design, compact and efficient boilers. They are also incredibly versatile when it comes to finding a suitable location to install them. So long as it is feasible to plumb the gas and water terminals and vent the combustion gases and condensate appropriately, then the limitations that might prevent the installation of alternative boilers can be overcome.

In general, the most suitable position for these boilers is in the kitchen or a location where they are easily accessible for maintenance, for example under the stairs, in a cupboard or even in a spare room.

In many homes, the main reason for installing a combi boiler is the limited space, which makes the necessity of extra water storage facilities like a feeder expansion tank and hot water storage cylinder impractical.

Shortage of space may also incline a householder to consider the positioning of a combi boiler in the unused space afforded by a loft.

It is perfectly feasible to install a combi in the loft, but certain factors must be taken into account and care must be taken to ensure that such an installation will be practical, especially when an easier and cheaper option might be the better choice.

Firstly, for a loft installation, considering its size, is it possible to get the choice of boiler through the loft entrance hatch and into the loft?

If the boiler will fit through the entrance hatch, is there a suitable wall to fix the boiler to, allowing for the plumbing and minimum clearances required by the manufacturer’s instructions?

A suitable location for securely fixing the boiler might be the chimney-breast or a supporting wall, but consideration will need to be made for the exhaust and air intake flue. This flue must vent the property inline with regulations. It must also be accessible for safety inspections.

In buildings with more than one storey, consider the water pressure. With increasing height, the water pressure is likely to decrease, especially if cold mains water is drawn off regularly at a lower facility. Check the proposed combi boiler’s water pressure requirements, bearing in mind that low water pressure may make the boiler operate noisily, or not operate at all.

Another consideration is the distance hot water will have to travel from the loft to the main hot water outlet points. A shower in a bathroom immediately below the boiler will be efficiently supplied, but hot taps in the kitchen may be far enough away from the boiler to be problematic. A considerable volume of cold water may have to be drawn from the system before the hot water from the boiler reaches the tap. This can be several litres, which will register on a water meter and could cost an extra £30 a year in increased gas and water usage.

Modern lofts are usually well insulated. This keeps the space below the insulation both warm in winter and cool in summer. Installing a combi in the loft, which in itself does not benefit from the insulation, can be problematic during extremes of temperature. Some combi boilers have a frost protection facility to prevent them freezing internally. This may be set by the manufacturer to operate at temperatures as high as 5º C causing extended and additional operating of the boiler and resulting in higher gas bills.

Condensate from the combi must be drained effectively and efficiently. A frozen condensate drainage pipe will prevent the boiler operating. Ideally, this pipe should be enclosed within the property to prevent freezing during very cold weather. Often insufficient consideration is given to this potential problem and a condensate pipe is run down an exterior wall. This pipe should be insulated. If it should freeze, an engineer might refuse to climb an external ladder to remedy the problem due to insurance considerations.

It is therefore advisable to insulate all exposed pipe-work in a loft as a precaution against frost.

It is also good practice, and of great convenience, to ensure that wireless controllers are fitted in a suitable location within the property. This will avoid the necessity of frequent visits into the loft. A filling loop also suitably located will save much inconvenience when topping up of the system is required.
Installation of a combi boiler in a loft is not the most popular of work undertaken by plumbers and gas appliance installers. They are inclined to charge more for the work than for a conventional installation. Working in a confined space can be difficult and some will not be prepared to undertake the work.

There are building regulations that should be adhered to regarding safe installation and access to combi boilers in the loft. BPEC CEN1 provides guidance regarding roof installation of gas boilers advising that:

The boiler should be mounted on wall capable of supporting its weight.
The loft must be accessible with retractable ladder.
The loft entrance and exit must be protected with a guardrail.
The loft must have fixed lighting in place.
Suitable flooring must be provided to the boiler for service access.
Gas, water, and electrical isolation points should be provided outside the loft to enable easy isolation of the boiler.

Some plumbers and engineers may be prepared to install a combi in the loft without regard to these statutory regulations, however such installations are bound to cause problems at a later date, particularly when routine maintenance, repairs and Gas Safe inspections are required.

These considerations may incline a householder to consider all other options carefully prior to deciding to locate a combi boiler in the loft.


Installing a New Boiler and Changing the System from Gravity to Pressurised.



If you have an old gravity fed hot water system and an equally old, inefficient boiler, you may consider upgrading to something a little more modern, reliable and efficient. Perhaps your gravity fed hot water pressure is just too low to meet today’s requirement of instant hot water and the increased demands of the household and water using appliances. Maybe you just feel uncomfortable about having a great volume of stored water literally suspended above your head and the potential for devastating water damage if the tank or supporting structure should fail.

Whatever your reasons, and despite inventive sales pitches and exaggerated claims by pushy salesmen, any decision to replace a gravity fed system with a pressurised one must be taken carefully. By not taking into consideration a number of important factors, an unsuspecting homeowner could end up with a new system that is far less efficient than the one it replaces.

The first thing to consider when confronted with claims made about the benefits and advantages of installing a pressurised system is the existing water pressure and flow rates. Despite elaborate claims to the contrary, performance from a mains pressure maintained system is only as good as the mains pressure and water flow rate that supplies it. Manufacturers and installers may give reassuring and appealing indications of the potential output from a system, but the reality is often quite different.

Always consult with your water provider prior to making the decision to install a mains pressure system. They can supply information relating to water pressure and flow rates supplying your property. If your water provider consistently delivers water at a pressure or flow rate below the levels required by a new mains pressure system, you might be better looking at alternative systems.  It is illegal to fit a water pump to the mains supply in an attempt to increase low water pressure and flow rates.

Where the water provider confirms a suitable pressure and flow rate, it is a good idea to check whether the pressure and flow rates are also adequate within the property. The diameter of the pipe-work from the provider’s communication pipe may be too narrow to maintain an adequate flow rate. Although a new water supply pipe can be installed, it will be the homeowner’s responsibility to shoulder the cost. This is something to bear in mind when costing the installation.

It is also a good precaution to ensure that the gas supply pipe is of an appropriate diameter to provide a new condensing boiler with a sufficient gas flow to operate efficiently. Old gas supply pipes are often narrow and may need replacing. Another potential cost to consider.

If these requirements can be adequately met, you may wish to consider simply installing a combi boiler if that system will supply your requirements.

Alternatively, if you have a large home and a high demand for hot water you might wish to consider a fully pressurised system.  A condensing boiler can provide substantial quantities of hot water and run a heating system all at mains pressure.

However, before embarking on this system, and particularly where old radiators are installed and the intention is to retain them, the system should be pressure checked. This will help to establish, although not guarantee, whether the central heating system can function under increased pressure.

Often, when converting from gravity fed to mains pressure, old pipe-work reveals and succumbs to weaknesses that are not evident under low-pressure conditions. It may be necessary to replace the entire central heating network. This might, of course, be necessary by virtue of its age, condition and inefficiency. Sometimes, adaptations and modifications over the years can produce a central heating system with a tangle of pipe-works of varying diameters and distribution paths that become problematic in relation to efficiency and maintenance. All the same, this possible replacement should be considered as a potential extra cost.

With a totally un-vented mains water pressurised system, it is important to fit a hot water storage cylinder capable of withstanding the high pressure in the system. Under no circumstances should an existing low-pressure copper cylinder be retained and used. High-pressure cylinders are generally made from steel and incorporate specialised pressure releasing safety devices either directly or remotely.

It is possible to install a mains water pressure system that incorporates a vented hot water supply at mains pressure. However, this system uses a process of heat storage and heat exchange to either indirectly or directly heat incoming cold mains water. This preserves the mains pressure but allows for expansion of hot water to be accommodated through an F and E tank, usually situated in the loft. This vented system does not store hot water under pressure and can be viewed as a safer alternative by some households.

Finally, when it comes to installation there are a few important factors to consider which may help a homeowner decide which mains water pressure system to install.

An un-vented mains pressure system will provide hot water at mains pressure to all taps and outlets and does not require any F and E tank or storage tank in the loft. However, it does require a specialised high-pressure storage cylinder and pressure release systems. A specialist engineering company with competent engineers must install an un-vented mains pressure system. The installation must be notified to Building Control at the local council and must be commissioned and certified by a registered engineer. An un-vented mains pressure system must also have an annual inspection to ensure compliance with regulations and its continued safe operation.

A vented mains pressure system will provide mains pressure hot water to all hot water taps and outlets. It will require a small F and E tank in the loft, or an appropriate place. It will require a small capacity heat-exchanging pressurised cylinder. It will have a vented hot water storage cylinder so there is no risk of explosion due to pressure build up. A vented mains pressure system does not require specialist installation and there is no requirement in relation to informing Building Control. The system does not require any specialist annual maintenance, although general annual maintenance is a recommended procedure.

Where mains water pressure systems are installed correctly, there is considerable benefit to householders in respect of improved energy efficiency and in meeting household requirements for hot water supplies at a convenient pressure.

But as a precautionary measure to spending a considerable sum on a system that is unsuitable, the homeowner should take into consideration the cost of purchase and installation, the flow and pressure rates of the supply, the general running and maintenance costs and the overall safety of the system.

In doing so the homeowner can make an informed decision away from elaborate marketing claims.






Understanding Energy Efficiency Rating Labels

In a way, it is not surprising that energy efficiency has become such an important issue. Never, on a global scale, have we consumed energy at such an alarming and exponential rate. Faced with finite fossil energy reserves and the spiralling costs of extracting the oil and gas from these diminishing deposits, it is fortunate that we can now utilise technology to reduce our consumption and ensure that what energy we do use, is used to maximum efficiency.

It is easy to see how we, as a country, have increased our demand and dependency on energy in the last forty years. Motor vehicles and an abundance of electrical appliances and gadgets have proliferated and become almost essential for modern living.

In the case of central heating, in the 1970’s it was installed in only 31% of homes. By 2003 that figure had risen to 93%. This led to a rise in home ambient temperatures from 12.1 C to 18.2 C and a rise of 4.5 C in homes with existing central heating installations during the same period.

The concept of abundant cheap energy, so much a characteristic of past consumption has been replaced by sharply rising fuel costs and drive towards better insulation of property and the efficient utilisation of heat production.

Appliance manufacturers have responded by specifically designing equipment with energy saving characteristics. Energy efficient products are designed to make the most effective use of energy with the minimum of waste. This means that the amount of energy needed to run them is reduced compared to a standard efficiency product.

All appliances are now subjected to standard testing procedures under a European Union directive, which enables the appliance to be categorised according to recognised levels of energy efficiency, and this information, in the form of a label, is required to be displayed on the appliance. The label is a colour coded graphic which rates products from ‘A’ to ‘G’, where ‘A’ represents the most efficient appliance with a stepped drop in efficiency down to ‘G’ which represents the most inefficient.

These alphabetical grades are used on items such as washing machines, refrigerators, cookers, light bulbs, etc and are designed to help consumers make informed choices when purchasing new appliances.

Although the above system is being adopted as a guide to efficiency by electrical central heating pump manufacturers, when it comes to boilers, a different and more reliable method of efficiency classification is required.

The basic measure of boiler efficiency is calculated from the ratio of the energy input compared to the heat output. High efficiency boilers require less fuel to produce the same amount of heat output to the system compared to less efficient boilers

The ‘A’ to ‘G’ system is still employed, but the method of assessing a boiler by its efficiency capabilities requires additional criteria and produces a rating based upon a percentage. This is because in domestic operational settings, the annual efficiency of the same boiler can be very different from one installation to another. It can be influenced by factors such as the circulation patterns through the property, the varying requirements for heating and the frequency and effectiveness of routine maintenance procedures.

To produce this alternative and more reliable model of classification, laboratory testing of boilers and a theoretical approach was compared with, and complimented by field trials carried out over a period of three years.

This method of rating is referred to as SEDBUK, an acronym for the Seasonal Efficiency of Domestic Boilers in the UK.

Originally launched in 2005 it was revised and updated in 2009 and re-launched on October 1st 2010.

Boilers are rated according to how much of the fuel that they consume is converted to heat represented as a percentage. An ‘A’ rated boiler will have an efficiency rating of 90% plus.

A ‘B’ rated boiler corresponds to 86% – 89% efficiency, with step reductions down to ‘G’ representing 70% and below.

In 2005 it became law that nearly all new boilers being installed had to be SEDBUK rated ‘A’ and ‘B’. These are high efficiency condensing boilers. Under the law, there is provision for some exceptions where ‘C’ and ‘D’ rated boilers may be installed, but these are quite restricted.

The European Union has legislation covering the energy efficiency of everything from homes and buildings to the requirement for the testing and classification of energy consuming appliances. This provides useful guidance for selecting appropriate items and the SEDBUK categorisation of boilers ensures that prospective purchasers of new boilers can be confident that they will purchase energy efficient appliances.

SEDBUK can also be used to obtain the efficiency rating of older boilers already installed in properties to gain some indication of current performance and to compare with new boilers on the market. This can be accessed online by consulting the SAP (Standard Assessment Procedure) database, which holds the information by manufacturer and model.

It can be useful to consider that around 10% of the energy costs of running a gas central heating system can be attributed to electrical components necessary for the efficient operation of the system. These include pumps, electrical diverter valves, flue fans and digital displays on boilers and thermostats.

However, on modern systems, the improved energy efficiency provided by the latest technological advances can considerably outweigh the electrical running cost of the components that contribute.


How to Buy the Best Boiler.

If you are in the market for a new boiler you can guarantee that there will be no shortage of persuasive sales representatives determined to grab your attention, and cash. You have probably already been seduced into the notion that an upgrade to a more modern boiler will deliver fantastic savings on your energy bill. It very likely will, but it may not be you that pockets the subsequent savings. Even the government’s Green Deal initiative grabs most of the money you would expect to save to cover re-payment and interest on a preferential loan.

The market is not quite as competitive as it could be with the major energy providers well placed to exploit customers who may already be signed up to their service and maintenance plans and contracts. Some independent installers are often not as independent as they might have you believe, with many having connections to the major energy suppliers or receiving healthy commissions from various boiler manufacturers.

It can be difficult to know where to turn to for good and impartial advice, and as you probably don’t have a distant cousin twice removed who used to be a heating engineer, or know a man who does, you may have to employ your own intuition to guide you into making the right choices.

One of the best starting points is to consider the type of system your current boiler services, and whether that system is suitable for your needs.

Many existing systems, whether they are open vented or sealed systems, and whether they have open vented hot water storage cylinders, sealed ones or none at all, are quite adequate. The main requirement is that the network of a heating system, which the new boiler is intended to provide hot water into, is in good shape, not too ancient and capable of modification to improve efficiency. It should also have adequate capacity for the household requirements for heating and domestic hot water.

If you are installing a boiler in a new build or complete renovation project you may have already decided to install the latest up-to-date central heating system with a state of the art boiler incorporating a capability to utilise renewable sources of energy. If that is the case then the boiler and system will be designed and installed to complement each other and the installation will be straightforward, and probably quite expensive.

The installation of a new gas boiler into an existing system is quite straightforward. It can also replace a different type of fuel burning boiler, if gas is available. In most cases a new gas boiler will have to be an efficient condensing boiler by law, and rated A or B on the SEDBUK scale, unless there are good reasons why an inferior rated or non-condensing boiler should be fitted. An example of this might be where a householder decides to replace an existing boiler with a cooking range system like an AGA or Rayburn.

Having established the currently installed heating system type and its suitability for continued good service, the next thing to look at is a replacement boiler capable of suiting those specific requirements.

There are three types of condensing boilers available.  Combination boilers, system boilers and open vent boilers. Boilers are available in a range of sizes and it is important to choose one that has the capacity to provide enough energy output to meet the system requirements.

There is considerable research to indicate that fitting a new boiler with substantially greater capacity than is required by the system has no adverse effects on overall energy efficiency. In fact, it is generally accepted that most new boilers fitted have a capacity in excess of requirement. Problems generally occur after the installation of a below capacity boiler when it is discovered that radiators are not hot enough.

It is, therefore, important that your new boiler is suitable for your existing system. A good boiler manufacturer will provide the information you need to ensure that the correct choice and size of boiler is selected. Most new boilers that are fitted as replacements are open vent or heat only condensing boilers, which supply hot water into the existing system of hot water cylinder and radiators.

This brings us on to boiler manufacturers and which offers the most reliable and best value for money appliance.

This matter is a little subjective and it can be argued that value for money is not quite the same as best value. Accordingly, a buyer should have a reasonable expectation of what popular makes of boiler cost. The most popular brand names are usually well tried and tested and combine proven reliability with customer satisfaction. Choosing a boiler from a company with such credentials can lead to peace of mind where the validity of extended warranties and the future availability of replacement parts are a concern.

There are some makes of boiler which are of simple design and quality and which are often the choice of builders, landlords and fit and run installers. These often prove to be poor value for money. Some of these boilers have parts that are simply not durable and consequently have a very limited lifespan. This is not to suggest that these boilers are unsafe. They just represent the lower and functional end of the market.

The best suggestion is to find out what boilers friends and neighbours use and recommend, and to research good quality boiler companies profiles and products on the web. The Energy Saving Trust produces a comprehensive list of recommended boilers.

Finally, a new boiler must be installed by a Gas Safe registered engineer. That person will of course guide you in the choice of boiler and the system requirements. However, before committing to an installation, it would be prudent to seek opinions and installation quotes from more than one engineer. Keep in mind that installation costs will need to be factored into the total boiler replacement cost.

It is generally a requirement that a power flush is carried out on existing central heating pipe-work and radiators at the time of installation in order to comply with a new boiler’s warranty conditions. Do not let an installation engineer circumvent this necessity, or offer to fit a magnetic filtration device as an alternative.

These precautions will help you to ensure you choose and buy the best gas boiler.


What are the Differences between a Combi Boiler and a Conventional Boiler?

Whether you are thinking about having a new central heating system installed or considering converting or upgrading an existing system to improve its efficiency, you will need to decide which boiler system is best suited to your property and your own personal requirements.

With heating boilers accounting for around sixty percent of household energy bills, the choice of boiler is becoming an important consideration, particularly when considering the replacement of older and now inefficient systems.

Combi boiler and conventional boiler heating systems tend to be the most popular of the three main central heating installations operating in domestic properties in the U.K.

There are distinct differences between these two systems. Both offer advantages and disadvantages, but the most important thing to consider is the limitation of each system.

So what are the principal differences?

When it comes to simplicity, a combi boiler has the advantage. It is now the leading type of boiler installed in the U.K. and is the boiler of choice if limited space is a consideration. The boiler can be fuelled by gas or electricity and, dependent on the need for a flue, can be fitted between cabinets in the kitchen or discretely out of sight in an under stairs cupboard. It is fed directly from the mains water supply, eliminating the requirement of system header tanks in the loft. It does require electrically operated pumps to circulate the heated water but these are usually discretely contained within the boiler cabinet.

Although the central heating is managed thermostatically by a regulated heat exchange between the boiler system and the separate central heating system, the domestic hot water supply is provided on demand. When the demand is initiated, a diverter valve operates to direct mains water through the heat exchangers whilst the boiler increases its fuel use and capacity to heat the mains water very rapidly. Once the demand for domestic hot water has been satisfied, the diverter valve returns operation back to the central heating system and the boiler reverts to room thermostat operation.

This system eliminates the need for a domestic hot water storage cylinder, which contributes, greatly to the combi boiler’s space saving qualities.

A combi boiler is compact and easy to fit and can provide unlimited domestic hot water but that domestic hot water tends to have a lower flow rate than the stored hot water of a conventional boiler system, and consequently, does not have the capacity to run multiple hot water outlets simultaneously. A combi boiler is ideal for a modest property although high capacity versions are available for larger homes. A combi system would be unsuitable for a property supplied by a low or variable pressure mains water supply.

A conventional or vented system requires space. The central heating side of the system requires a cold-water storage tank to supply the domestic hot water component and small feeder and expansion tank to supply the central heating component. Both of these are usually located in the property loft.  In addition, a domestic hot water cylinder storage system is required and this is usually situated in the airing cupboard. In some systems, particularly gas fired boilers; this domestic hot water cylinder may incorporate an additional thermostatically controlled electric heating element to provide an alternative power source for that part of the system.

With a conventional system, domestic hot water supply is limited to the capacity of the hot water storage cylinder, and once that supply has been exhausted, say with the filling of a bath, a period must elapse before the stored domestic hot water supply has been re-heated to the thermostatically controlled desired temperature.

However, the traditional system has the advantage of being able to supply multiple hot water outlets simultaneously, although water pressure may become an issue if demand is too great. The hot water available is always governed by the capacity of the hot water storage cylinder.

For households seeking a high degree of efficiency from their boiler systems it might be worth considering that the domestic hot water storage system of a conventional boiler has the disadvantage of losing heat from the cylinder, even when insulated with a cylinder jacket.

In fairness, the choice of system has to be made based upon the requirements of the household, the property characteristics and the limitations of the systems. Whichever system is decided upon it should be borne in mind that the boilers on the market of either system today are vastly superior in terms of energy efficiency than their counterparts of ten or even five years ago.

However, boiler efficiency is a combination of many factors including regular maintenance and sensible energy consumption. There would be little or no benefit obtained by replacing an old boiler with a new energy efficient one without thoroughly flushing and protecting the old radiator system and installing new thermostats and system programmers to compliment and regulate the efficient running of the system.

Improving and maintaining the energy efficiency of your own home is the only answer to the present fluctuations in market price and the predicted long-term increases in the cost of energy.