Do I really need to line my chimney?

'Do I really need to line my chimney' is a question asked by a lot of our customers. This is the answer! Most chimneys, certainly in older properties, were designed for open fires where you astonishingly lose 80% of the heat up the chimney and only get 20% into the room - as well as having a wicked draught around your ankles. Open fires are what wing-backed chairs were designed for! All of this heat takes up a fair amount of room in your chimney and travels upwards quickly. It's travelling so fast that it doesn't cool and condense until it reaches the top and all the exhaust gases and any nasty tar, creosote and condensates are successfully expelled. This is how an open fire and chimney should work. 

When you put a stove or woodburner at the bottom of your chimney, you instantly reverse the ratio. Roughly 80% of the heat comes into the room and only 20% is lost up the chimney. This vastly smaller amount of hot air swirls around your large chamber, moves upwards much more slowly and leaves behind all sorts of sooty deposits which form as tar and creosote on the inside of your chimney, providing much more scope for a chimney fire. It is inevitably going to cool and condense before it reaches the top and the condensation, when mixed with sooty deposits, produces sulphuric acid which eats into the mortar and brickwork of your chamber. Over time this can affect the structural integrity of your chimney or cause minuscule cracks through which fatal carbon monoxide can leak. 

By lining your chimney your chamber becomes a smaller and constant size all the way up enabling the smaller amount of heat to rise faster and not condense before it reaches the top. You have recreated your open fire chamber in a smaller version to accommodate the smaller amount of gases! By having a smaller and constantly sized flue, you have also made it much easier to sweep and there is no scope for flammable creosote to collect in any nooks and crannies! 

If this isn't enough of an incentive, an open fire draws ferociously (hence the draught and the need for your wing-backed chair) as it has to feed the big chamber. A woodburner or stove cuts off this massive updraught as you are controlling the air intake so you need to reduce the size of your chamber to maintain the status quo of the draw. Imagine drinking a drink through a fat straw and a thin straw.... the thin straw is much faster and easier. 

Building regs don't state that you have to line your flue when fitting a woodburner or stove, however they do state that you must be sure that the chimney is in good working order and has been sufficiently maintained. In our view this is a very difficult thing to have long standing peace of mind over! For all the good reasons stated, most, and certainly the conscientious installers will strongly recommend fitting a liner and may even refuse to install your stove without fitting one. 

If you are still in doubt as to the need, give your local fire brigade a call - get their view on installing a stove or woodburner without lining the chimney!