Appliance types

• Regular boilers are designed to heat water within a heat exchanger by absorbing the heat contained in the flue gases created by the burner.
• Sealed system boilers Regular boilers and combination boilers include a circulating pump, expansion vessel and other components needed for a “sealed system” and don’t need an expansion cistern in the loft space. Both regular and sealed system boilers require a separate hot water cylinder.
• By contrast, combination boilers can provide hot water on demand, as well as heating. This saves space because no hot water cylinder is required. However, sufficient water supply pressures and flow rates are required for optimum performance.
• Range cookers have been available for many years. Some models have integral boilers making them capable of providing central heating and hot water too.
• Room heaters or stoves have decorative effect fires that burn fuel through imitation coals or  wood behind a glass front. Some also have back boilers to provide hot water and/or central heating service.

Appliance efficiency

Older appliances typically operate at only 60–70% efficiency. Modern condensing appliances, however, can exceed 90% efficiency and are available as regular, system, and combination boilers. Installing a condensing appliance is an excellent way to reduce running costs compared with non‑condensing models — you could achieve fuel savings of up to 30%. To comply with building regulations all new or most replacement boilers must be of the condensing type. Non-condensing boilers can only be fitted if the building qualifies for an exemption which is based upon an assessment of the technical difficulty and cost associated with installing a condensing model.

Systems and controls

Modern high efficiency condensing appliances use an electric pump to circulate the heated water around your heating system. If you have an old heating system or one which doesn’t use a pump to circulate the water, it must usually be upgraded to a fully pumped system when the appliance is replaced. Accurate system controls can help you save money by reducing heat wastage. There is a vast selection of modern controls available to increase energy efficiency which will help keep your fuel bills down. It may be possible to fit devices such as weather compensation or smart controls.

Flues and combustion air/ventilation

In heating systems where fuel is burned, combustion gases are released which must be safely expelled from the appliance and discharged to outside air. Regional building regulations provide strict guidance on how this should be done.

Types of flues

There are two main types of flues that convey combustion gases away from an appliance: ‘balanced flues’ or ‘open flues’. Many liquid fuel appliances have balanced flues, which offer great versatility in terms of siting the termination. These can be low or high level through a wall, or vertical through the roof. Balanced flues also have the advantage of carrying fresh air for combustion from outside, back to the appliance. This means that for most installations there is no need for additional air vents to be provided for the appliance. Some liquid fuel appliances have open flues. An open flue typically consists of a pipe to carry combustion gases from the appliance, whilst fresh air enters the appliance via the casing. This means that, for safe operation, additional air vents are required in the room where the appliance is installed to re-supply fresh air. Liquid fuel appliances that are installed outside are usually fitted with flues built into the side casing, as well as additional vents for fresh air.

The flues from most appliances can terminate via an existing masonry chimney as long as the chimney is in sound condition (does not leak smoke into upstairs rooms or adjoining properties) and meets the manufacturer’s requirements. In most cases it will be necessary to fit a suitable flexible lining system. Flexible liners should be replaced whenever a new appliance is fitted.

Air supply

Oxygen is required for fuel to burn, so it is essential to provide a dedicated air supply path to the appliance. Depending upon where the appliance is located, it may be necessary to provide additional ventilation for cooling purposes. Air supplies to the appliance should be provided via non-closable air vents unless a balanced flue is being used. The size of the vent(s) depends upon the flue type, the appliance output and location, and where the air supply is taken from.

Balanced flued liquid fuel-fired appliances take air via their flue system, which has been designed by the appliance manufacturer. This benefits the home’s heat efficiency because no additional air vents are required, unless the appliance is located within a confined space and requires cooling. Open flued appliances take their air from the room in which they are located, so adequate ventilation is needed to replace the air that passes through the appliance. This is usually done by installing air vents in the room. Open flued appliances should not be installed in or take their air from a bedroom, bathroom or garage - balanced flue type installations should be used in these locations. If an extractor fan is in the same room as an open flued appliance it may cause interference to the air supply - your OFTEC registered technician can advise on the air supply requirements to ensure safe working operation of your appliance.

Safety

Every type of flue and chimney should comply with European and national legislation regarding materials, design and flue termination point. Flues should terminate where the combustion gases will disperse quickly and will not re-enter the property or cause a nuisance to neighbours. Termination below a car-port or any other area where flue gases might stagnate should also be avoided. Extra care is needed when selecting a suitable position for a condensing appliance flue termination. When operating at their most efficient, condensing appliances can emit a ‘plume’ of water vapour from the flue terminal, which should be considered when siting the appliance. Your OFTEC registered technician  will be able to advise on the most suitable flue system to ensure compliance and reliable operation.

More information on location

Modern condensing appliances will emit plume (water vapour along with other by-products of combustion) from the flue; this is most visible on colder days. Extra care needs to be taken when siting a condensing flue to avoid the plume causing a nuisance to you or your neighbours.

Garages are often used for siting appliances. To prevent car fumes from being drawn into the appliance, a room-sealed, balanced flued appliance should be used so that fresh air for combustion is taken directly from outside via the flue system.

If internal space is at a premium, it is worth considering appliances that are designed to be installed externally or “through the wall”.

Fuel supply pipes

Domestic fuel supply pipes are usually made of plastic-coated soft copper tubing that can be easily manipulated. Plastic pipe systems are also available but must only be used below ground, outside of buildings.

External/exposed pipes

For best performance, fuel supply pipework should take the most direct route between the fuel tank and burner, while avoiding high points in the pipework, the creation of trip hazards, or anything likely to damage the pipe and joints. Pipes should be supported by purpose made clips and attached to permanent structures, such as a wall. A garden shed or wooden boundary fence is not classed as a permanent structure because it will deteriorate with age and any movement may damage the pipe and fittings.

Entry into buildings

Where a fuel supply pipe passes through the wall of a building it should be run within a sleeve, such as a larger plastic pipe. Fuel supply pipes should not be run underground directly into the interior of a building, instead, the pipe should rise externally to allow a remote acting fire valve to be fitted before it enters the building.

Fire valves

A fire valve is an essential safety feature of a fuel supply installation, which will stop the supply of fuel in the event of a fire, or overheating of the appliance. The valve should be located outside the building, before the point of entry, and be activated by a remote sensor. Existing fuel supply pipes that are not accessible outside of the building, and do not have a fire valve, can have one added at the first point where the pipe appears internally. This is not permitted on a new pipe installation, but it can improve the safety of an existing installation. Fire valves are also required for externally located appliances. Your OFTEC registered technician will be able to offer advice on the correct selection and positioning of fire valves.

Buried fuel supply pipes

Buried fuel supply pipes should be protected against the risk of accidental damage caused by digging.

The recommended installation method is as follows:

• A trench should be excavated to a depth of 450mm.
• 40mm of compacted sand is laid on the bottom of the trench, the fuel supply pipe is positioned, and a further 40mm of compacted sand is laid above the pipe.
• Builder’s grade polyethylene is laid above the sand, and the trench is then backfilled, positioning fuel supply pipe warning marker tape 150mm below the finished ground level.
• Fuel supply pipes should be buried at least 300mm clear of other underground services such as water and electricity. Joints should be avoided in buried pipework, if possible. If joints need to be made, they should be within an inspection chamber.

Minimise pollution risk from fuel spills

In some regions, to minimise pollution risk from fuel spills, it is now mandatory for tanks to be bunded. This means there is a secondary containment either integral to the tank or built around it. In other regions, your OFTEC registered technician will conduct a risk assessment and advise accordingly, but typically tank installations near a river, well, or any controlled water will require bunding.

Fuel tanks have an expected working life of around 20 years with the risk of a costly tank failure increasing with age. Your fuel tank should be inspected every year as part of your annual heating system service and your technician will advise you when you should replace your tank. Your fuel delivery contractor may also highlight issues with your tank and, in extreme cases, could refuse to deliver if they have concerns about the tank’s condition. It is common practice for a contractor to apply a warning notice to a fuel storage tank in addition to reporting any defects to you.

Tank support

If a fuel storage tank is not adequately supported, it could lead to safety concerns, the eventual failure of the tank and even a fuel spill. The base needs to provide continual structural support, even though ground conditions may vary from season to season.

The base should be:

• Adequate for the weight of the tank and its contents – 1000 litres of fuel weighs just under a ton.
• Non-combustible, imperforate and level.
• Constructed of concrete, paving stones or stonework.
• Large enough to extend 300mm beyond all sides of the tank.

What are the regulations on the location of a liquid fuel tank?

There are now very specific rules governing the location of tanks and it’s important to take these rules into account if you are making subsequent changes to your property. The rules are in place for fire safety reasons and although a fire is highly unlikely to originate in a fuel storage tank, it is very important to protect the stored fuel from fires or heat sources nearby.

To protect tanks from an ignition source, tanks should be sited:

1.8m away from a non-fire rated building or structure (e.g. garden sheds).

1.8m away from openings (such as doors or windows) in a fire rated building or  structure (e.g. brick-built house/garage).

1.8m away from liquid fuel appliance flue terminals.

760mm away from a non-fire rated boundary, such as a wooden boundary fence.

600mm away from screening (e.g. trellis and foliage) that does not form part of the boundary.

If it is impossible to comply with these separation distances, then a fire protection barrier (with a minimum 30 minutes fire rating) should be provided. The separation distance required between the tank and the fire barrier should be a minimum 300mm unless a greater distance is specified by the tank manufacturer. It is possible to site a fuel storage tank inside a garage or out-house; however, they need to be self-contained within a 60-minute fire rated chamber.

Looking after your tank

Tanks should be visually checked by a competent person at the time of your annual appliance service visit. OFTEC also recommends regularly carrying out a visual check between service visits particularly after periods of extreme weather conditions as this can put tanks under additional stress. If you have any concerns, always contact your local OFTEC registered technician  who can advise fully.

Warning signs to look out for

You must check whether your home insurance covers fuel spills or leaks and whether here are any stipulations or limitations to your policy.

These are some of the warning signs to look out for:

• Rust.
• Splits or cracks.
• Bulging.
• Gauges falling over or not working.
• Subsidence on the base.
• Sudden increase in usage of fuel.
• Tanks overgrown with foliage.
• Strong fuel smell.

What paperwork will be issued for installations?

Upon installation work, the OFTEC registered technician will complete a CD/10 (installation completion report) for the work which was undertaken for your records. The technician will then notify the local building control body so that a works notification certificate can be issued. This notification is optional in Scotland and Ireland.

What paperwork will be issued for commissioning?

Installed appliances require commissioning to ensure that they are working safely and efficiently. Upon completion of the work, the OFTEC registered technician will complete a CD/11 (service and commissioning report) for your records.

Without regular servicing, the efficiency and reliability of the appliance will be affected

Reasons could include:

·         Excessive smoke and partially burnt fuel deposits can cause soot to form within the appliance heat exchanger. This restricts the amount of heat that can be transferred into the heating system water. The cleaner the heat exchanger, the more efficient the appliance will be.

·        Fuel nozzles regulate how much fuel passes through the burner. Nozzles are consumable items that wear over time, affecting combustion and lowering boiler efficiency. If they are not replaced this may cause “sooting up” of the heat exchanger due to too much fuel passing through the burner.

·         Fuel pumps contaminated with debris and/or water can cause premature failure.

·        Flame sensors can glaze over with deposits. Flame sensors are an important safety feature which detects whether the appliance has lit. If a flame sensor is dirty it may not be able to detect the burner flame correctly and could cause the appliance to shut down randomly. Appliances frequently switching on and off will be less efficient than those running for longer periods.

·        Electrodes can wear and attract soot and deposits. Electrodes produce a spark to light the fuel, if they are worn or in poor condition, the appliance may not light. Again, this causes inconvenience, inefficiency and increases fuel costs.

The service

Appliances should be inspected and cleaned, and consumable items such as fuel nozzles and flexible fuel lines should be replaced as required, when the appliance is serviced. If your appliance is not serviced annually, it is at a higher risk of breaking down and costing you more money in the long run. 

Cleaning the appliance provides a chance to look for other tell-tale signs that parts of the appliance may need replacing, and an opportunity to inspect the condition of the combustion chamber. Old steel heat exchangers will often have rust marks, which can give a warning that the appliance will soon need to be replaced. This approach can limit the possibility of water damage occurring and enables replacement work to be planned rather than having the inconvenience of trying to arrange an appliance replacement at short notice when a heat exchanger unexpectedly fails.

Long term damage can also occur if the appliance is not serviced regularly. During the combustion process, deposits will build up on the internal surfaces of the heat exchanger and the baffles, which can decrease appliance efficiency. If left for several years, these deposits harden and with some designs of heat exchanger render it impossible to remove the baffles without destroying them. A replacement baffle will come at a significant cost on top of the routine service charge. Open flued appliances should have their flues or chimneys swept regularly as advised by your service engineer for liquid fuel-fired appliances.

Any combustion and/or ventilation air openings should be checked for their correct size and ensuring that they are free from obstruction

We recommend using a member of a recognised sweeps’ organisation these can be found on The Federation of British Chimney Sweeps  website.

The condition of the fuel storage tank, fuel supply pipework and all ancillary fuel supply components (such as filters, de-aerators) should always be visually inspected and observations reported during service visits, so action can be taken to replace, or repair equipment as necessary. Fuel filter elements should be replaced and the fuel inside the tank should also be tested to determine if any water contamination is present. Fuel supply pipework between the tank and the burner which is hidden or inaccessible should be pressure tested at least every five years to confirm its integrity.

What paperwork will be issued for servicing?

The OFTEC registered technician  will complete a CD/11 (service and commissioning report) for your records. This is a record of maintenance undertaken, results of combustion tests and details of any parts that havebeen replaced.