Installing a wood burner boiler stove or other heating appliance and planning to run your flue system through a wall or a floor, you will need to use a twin wall flue system.
Twin wall flues have a 1 inch of insulation around the inner layer pipe. The external diameter of twin wall pipe is two inches larger than the internal, which is the quoted diameter. This is due to the internal diameter being a crucial figure when drawing and designing a wood burner flue system, you should always keep in mind of this when installing, for instance if you were to be careless and purchase a 5 inch diameter twin wall pipe the external diameter will be 7 inches it could very well be too big for the install!
If you are passing through a wall you must always set it at the maximum angle of 45 degrees and also use a wall sleeve. You can finish the job off with finishing plates. If you are passing through an internal floor in your home you will need to use fire stop plates and remain at least 50mm away from combustible materials like joists.
Always have at least one length of single wall enamelled stove pipe as you cannot connect your twin wall pipe directly to your wood burner’s flue. It is then possible to use single wall pipe internally, we recommended that you do not go more than 1.5 meters before changing to twin wall but you certainly need to convert at least 4 inches before passing through a wall or floor. You should use an adaptor to single wall to allow you to convert to twin wall flue pipe and then once you have converted you must continue the flue system in twin wall.