frequently asked questions

All chimneys built after 1966 will have had a ceramic or concrete liner fitted at the time of construction. It was not a requirement to fit liners into chimneys built before this date, many of which had a cement render instead. Of course, some chimneys may have been lined since, due to a steady deterioration of the brickwork, or may now need to be lined to repair the ravages of time.

You may be aware of smoke leaking through the brickwork into parts of the house, such as bedrooms and attic spaces or smoke coming out of an adjacent chimney pot. You should have the chimney checked and tested by a competent installer or chimney engineer to assess what action should be taken. All appliance installers should check the chimney for suitability before commencing the job. It is unsafe to use an appliance if the chimney is leaking.

 Building Regulations Approved Document J requires the installer to check the chimney to ensure it is suitable for the intended application. They should carry out visual checks to determine flue size, followed by a pressure smoke test. If the chimney is suitable for the intended purpose it can be used without modification, however any failure will require the fitting of a suitable flue liner.

There are various systems available to suit your needs. Download the SFA leaflet, ‘Lining Old Chimneys’ for more details. (See literature page)

Most flexible liner manufacturers make this optional. However, maintaining the temperature of flue gasses is important to ensure the chimney works efficiently. A cold chimney, due to location and exposure to cold winds etc will not perform well, therefore insulation is recommended. You should always follow manufacturer’s installation instructions and guidance.

Subject to the quality and thickness of the liner, all manufacturers offer a warranty period. However, premature failure can occur if the fire is run for extended periods at a slow burning rate. Consequential low flue gas temperatures can lead to a build up of condensation within the flue which, when in contact with flue gasses, cause an acid which attacks the internal surface of the liner resulting in flue failure.

Most homes can have a prefabricated stainless steel twin wall insulated flue system fitted to comply with the requirements of Building Regulations and appliance manufacturer’s installation instructions.

Many house insurance companies make this a requirement. HETAS Ltd have issued a guidance note on this subject which can be downloaded from , (Trade – Safety Notes & Guidance)

Invariably this problem arises as a result of condensation which results in water droplets forming on the inside of the flue. This water mixes with the flue gasses to create a substance which resembles creosote. This commonly happens when burning unseasoned wood which contains high levels of inherent moisture. It is recommended you only burn seasoned wood or kiln dried product with a moisture content of 20% or less. A simple moisture meter will help determine if your logs are suitable for burning.

Deposits can stick to the inside of glass doors which may be difficult to clean. There are effective cleaning products on the market but it is imperative to avoid any abrasive materials which can scratch the surface and cause permanent damage. It is better to avoid discolouration by burning the fire at a higher temperature to limit the risk and only burn fuels appropriate for the appliance type.

Completion Certificates can only be issued by either a Building Control Officer at your local authority or a Registered Engineer belonging to a Competent Person’s Scheme, such the one run by HETAS Ltd. However, CPS Members can only sign certificates for work they have undertaken. Work undertaken by an installer not registered with a CPS member or DIY will need to be certified by your local Building Control Office.

 This is a complex question. If you employ an engineer to supply and fit a stove, they will expect to make some profit out of the stove sale. Their operational overheads remain the same regardless of the size of the job and therefore they will need to charge more for the installation work to compensate. Many customers find this unacceptable. In addition, the warranty for the stove is the responsibility of the supplier not the installer which will result in complications if you need to make a claim. As a consequence some engineers are reluctant to quote for this type of work.

It is important to select the right size of fire to heat the room and any heating system to which it may be connected. This is an expert job and should not be left to guesswork. Based on room size and construction, the optimum room-heating output should be calculated in order to identify the most appropriate appliance. Similarly, any hot water requirement should be calculated so as to select the correct sized boiler.

Building Regulations Approved Document J requires suitable hearths be provided beneath a solid fuel fire to eliminate risk of a house fire. (Both constructional and superimposed hearth.) Sizes and thicknesses are detailed in ADJ, which vary depending on the type of appliance to be fitted.

Clearances to the side, rear and above the stove are determined by the appliance manufacturer and should be found in their installation instructions. They should recommend distance to both combustible and non-combustible surfaces, thus is important to determine the materials involved.

 Unless you can obtain the minimum clearances recommended the surface must be lined with non-combustible materials, ideally a sand and cement render with plaster finish. Wall boards must be certified non-combustible (not fire retardant). Plasterboard is not suitable for this purpose.

Provided all appliances are designed to operate with open vented systems there should be no problem. There are several devices on the market to enable this link-up to work successfully. SFA provides a simple ‘Link-up’ leaflet to explain things further. (See literature downloads)

Many modern gas and oil condensing boilers are designed to operate with pressurised heating systems and would not be compatible with the majority of solid fuel and wood burning appliances which require an open vented system. Unless the selected solid fuel appliance is specifically designed to operate with a sealed system it could prove a dangerous option. You need to seek expert advice on this issue.

No. The Health & Safety Executive have issued a directive requiring that all redundant back-boilers should be removed and replaced by a standard Milner Fireback.  The tradition of drilling the boiler and filling with sand is no longer considered safe.

Current Building Regulations provide information on actual ventilation requirements for different appliance types. Open fires always need an ample air supply to enable the chimney to work efficiently to remove flue gasses safely to the outside. By comparison, stoves require much less ventilation, subject to the appliance nominal heat output. Modern homes built to higher air tightness standards will require particular attention.

All domestic fuels when burned create flue gasses which invariably contain amounts of carbon monoxide. Carbon monoxide is a clear and odourless gas which is very dangerous to humans and animals. You should never expose yourself to smoke or fumes from a heating appliance of any type. If you experience fumes in any situation, ventilate the room and evacuate the building. Do not attempt to extinguish a coal or wood fire, allow it to burn out. Ideally purchase carbon monoxide detectors and locate in them in the room where the fire is situated and any upstairs rooms through which the chimney passes. The young and elderly are particularly vulnerable to CO poisoning.

 Since 2013, the Building Regulations Approved Document J requires all new solid fuel appliance installation be provided with a CO detector fixed at high level in the same room as the fire. Further, the SFA recommends CO detectors are fitted to all homes where solid fuel appliances are installed including bedrooms where the chimney passes through that room. 
From 1st October 2015 it became mandatory that all rented properties must have carbon monoxide alarms fitted in rooms where heating appliances are operational.

All chimneys should be swept at least once a year. Depending on the frequency of use and the type of fuel burned it may need sweeping more frequently. Similarly, it is necessary to have the appliance serviced annually to maintain safe and efficient operation.

Building Regulations warn against installing an open flue appliance in the same room as a mechanical extraction fan. The danger is that the fan could, under some circumstances, draw air down the chimney and thereby suck flue gasses into the room. Of course, the risk will depend on room size, ventilation levels and the type / size of the fan unit. In practice, a smoke spillage test should prove whether the fan will interfere with the flow of gasses up the chimney. Additional ventilation may be required.

There are many various styles and designs of chimney cowl on the market. Not all are suitable for a solid fuel appliance installation. As a general rule, you should only contemplate fitting a cowl if there is a particular need to do so. It is imperative the chimney is capable of discharging all flue gasses quickly and efficiently to the outside of the building. Some cowl types restrict the gas flow and cause smoke to spill into the room. A chimney should be capable of operation without a cowl, but sometimes due to local conditions an alternative design of chimney terminal will work better or prevent the ingress of rain. (See Curing Chimney Problems leaflet download)

Many urban areas are subject to Smoke Control Orders dating back to times when smoke from both domestic and commercial chimneys caused air quality concerns. These restrictions still apply despite the fact that smoke pollution is minimal today. The Environmental Health Department at your local council should be able to advise you if your home is within an area.

If you live within a Smoke Control Area, it does not mean you cannot enjoy a solid fuel fire in your home. The Act requires you burn only an authorised smokeless fuel, of which there are many available, or install a DEFRA exempted appliance which is able to legally burn unauthorised fuels, for example, wood.
More information can be obtained from SFA Helpline – 01773 835400

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