My name is David Campbell. I have been a registered chimney technician in Northern Ireland for close to 20 years. I am also PR Manager and Secretary of the Northern Ireland Association of Chimney Sweeps. I have been an approved instructor for the NIACS for about 12 years and have given presentations and seminars for Building Control It still amazes me that many architects, surveyors, health & safety inspectors and even Building Control inspectors themselves often have very little understanding of what is required within our specialised world of solid fuel heating. The spotlight is only turned on when major incidents such as structural damage caused by fire or Carbon Monoxide fatalities occur, which is too late.
Buy British or Irish… it shouldn’t be a label reserved for our butchers shop window. Some of the best-engineered stoves in the world are built here in our home countries. The Scandinavians seem to be pretty handy too admittedly, but the key to all stoves working correctly is the need to install it correctly and use the correct, DRY fuel. Popular brands made in the UK and Ireland would be Hunter, Villager, Yeoman, Tripp, Stovax, Charnwood and the leading manufacturer of clean burning stoves, Clearview stoves. A lot of stove manufacturers outsource production to foreign parts, and surprisingly some of these would be well known names associated with UK and Irish companies. Caution should be used when selecting your product. Professional chimney technicians for many years have worked with them all, and some are better than others.
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It is a building control requirement that if you are changing the use of a chimney to any other application, it is necessary to have the chimney or flue visually inspected by a recognised and preferably registered chimney technician with an approved body, to ensure it is safe and suitable for the application. In building control documents J and technical booklet L for Northern Ireland it is deemed advisable to reduce the diameter of a flue down to suit the intended appliance. Clearly by doing this, you are going to maximize the efficiency of the appliance. A kilowatt output test is based on the correct diameter of flue for the product being tested among other things, therefore attempting to install into a flue bigger than is required can be unsafe and reduces the performance of your investment
More often than not, it is advantageous to install a flexible steel liner. A good quality manufacturer of 316 flexible steel should be used to reduce the diameter down to suit the stove you have purchased and you will ensure maximum efficiency if you are only burning wood and turf. For any other fuels, it is considered a better practice to use 904. Most of the registered chimney technicians in Northern Ireland would use Docherty Chimney Group products, considered one of the superior products within the industry. Clearview stoves, made in Shropshire, will show this in their installation guidelines as a requirement. Their stoves are some of cleanest and most efficient in the world, and are selective about who can sell their products because they know how critical the flue is to ensure safe and desired performance of the appliance. Other manufacturers consider this type of installation as good practice.
An open fire can lose up to 90% of its heat up through the flue, which encourages a high Flue Gas Temperature (FGT). A stove will offer about 65-90% efficiency depending on which you buy, and therefore will require a much better performing flue system. Clay or ceramic liners, or heaven forbid, an old brick or stone chimney, will not be able to maintain temperatures of combustion gases on a slow burning stove. All too often clay liners have very little or no insulation behind them, and are commonly installed upside down allowing condensates to leak from the joints. Condensate products are as a result of moistures in the fuel generating steam during a burn cycle, but cooling past their due point and forming a sticky treacle like tar in the flue system before they have a chance to vent safely into the atmosphere. Shiny creosote deposits can burn at temperatures of over 2000 degrees Celsius, and will cause significant damage to property.
Read on A Message From David Campbell, Chimney Sweep Association, Pt. 2
