When people report problems with the performance of their wood burning systems, the cause is often traced to the chimney. Selecting the correct chimney and designing the layout of the installation is critical to good performance. And knowing how chimneys work is useful in the day-to-day operation of the appliance.
Chimneys operate on the principle that hot air rises because it is less dense than cold air. When a chimney is filled with hot gas, that gas tends to rise because it is less dense than the air outside the house. The rising hot gas creates a pressure difference called draft which draws combustion air into the appliance and expels the exhaust gas outside.
The chimney’s function is to produce the draft that draws combustion air into the appliance and safely exhaust the combustion gases to the outside. But a good chimney must do more than that.
The chimney flue should be the same size as the appliance flue collar. Chimneys that are over-sized for the appliance they serve are common, partly because people used to think that bigger is better. Now it is clear that bigger is not better when it comes to chimney sizing. A given volume of flue gas flows faster and has less time to lose heat in a small chimney flue than in a large one.
Monday, Tuesday, Wednesday and Friday: 9.00am – 5.00pm
Late Night Opening: Thursdays until 7pm
Saturday: 9.00am – 1.00pm
Out of hours appointments available on request.
Unit 1, Garlands Trading Estate, Cadley Road, Collingbourne Ducis, Marlborough, Wiltshire SN8 3EB
Tel: 01264 850742