Frequently Asked Questions
- 1. Why does my chimney need lining?
The first and most obvious reason for lining is if your chimney leaks ie. You get smells in the bedrooms and/or loft space or if there are tar stains on internal plasterworks or external brickwork.
If required a CCTV survey and smoke test will determine the condition of your chimney, answering all kinds of questions and enable the most appropriate solution to be specified.
The second reason concerns the physics of burning wood in a stove. A chimney needs to be warm to allow the stove to draw properly and prevent the rising emissions from cooling and condensing, which over-time leads to the build-up of solidified tar deposits. The construction of a chimney is likely to be of stone, brickwork or lined with clay and of a wider diameter than is suitable for a stove; these chimneys do not warm sufficiently, cool the stove gases and therefore lead to formation of condensates and tarring.
The installation of a stainless steel flue liner helps to maintain flue gas temperature and most stove manufacturers require that the chimney has a suitable liner of the correct size and specification to ensure safe and efficient operation of the stove.
- 2. What output do I need?
There are two things that determine stove size; required heat output for the room, and the actual or potential size of the existing fire place.
To calculate the required heat output divide the cubic capacity of the room (width x length x height) by 500 if working in feet or by 14 if working in meters. This gives you the kw output needed of a stove and should be your main guide to choosing an appropriate stove. Modern stoves have optimum temperatures at which they need to operate to give their true efficiency. Therefore just because you have a large fireplace it does not mean you should fill it with a large stove. If you consistently run your stove at a lower temperature you run the risk of tarring up your flue and your stove will not operate efficiently also causing consistent blackening on the glass.
Secondly – will the stove fit into my fireplace? The space around a stove is important to allow the heat to escape to the room and avoid damage to the stove. It also looks better if the stove and fireplace are kept in scale.
- 3. What is HETAS?
Solid fuel installations must be approved by local authority Building Control as complying with current building regulations. HETAS is the wood burning equivalent of GAS SAFE (CORGI) to gas appliances and is the recognised certifying body. HETAS engineers are trained and qualified in installing stoves giving you the peace of mind that the job has been done safely and in accordance with current building regulations. On completion of installation a Chimney Data Plate will be secured in a suitable location providing install details along with the issue of a Certificate of Compliance. If your stove is not installed by a HETAS registered installer you must obtain inspection and approval from your local authority Building Control for which there will be a fee according to your local authority fee scale.
- 4. What kind of wood should I burn?
It doesn't matter what kind of wood you burn as long as it is seasoned (split and stored for 18 months) untreated and dry. Dry, well seasoned wood produces a lot of heat and burns clean!
USEFUL FACT: 1kg of wood (20% or less moisture content) generates 4kw of heat.
- 5. Why are stoves efficient?
Modern stoves achieve maximum efficiency by extracting the heat from the wood in two ways. The first source of heat is from the initial or primary combustion, this you see first as flames from the wood. The second source is from the combustion of those gasses which are released un-burnt from the primary fire. This gas/smoke is laden with usable fuel in the form of tars and creosotes. Once the stove gets to the right temperature these gasses themselves are ignited and burnt before they escape to the chimney, thus providing a second source of fuel. This will double or even triple the heat output from the same amount of wood!!
- 6. Can I install a stove myself?
We don't really recommend this but if you do decide on the DIY route we can offer advice on installations and supply all the necessary components thus making sure the installation complies to building regulations. Remember – you will have to get it inspected and signed off by Building Control.