Why Doesn’t My Stove Work? – Spring & Autumn Syndrome

There are a multitude of common misconceptions surrounding how a stove operates and in this series of Why Doesn’t My Stove Work? articles, we hope to dispel the myths and clearly underline the actual causes and simple solutions.

First and foremost, it is essential to recognise that the flue (chimney) is the engine that powers a stove. The basic fact is a closed heating appliance such as a wood burning stove without a flue will not work (and vice versa if you felt the need to try that).

There is a lot of ‘science stuff’ going on inside your flue system that powers your stove and below are three main driving factors:

  • It is not the heat of the stove or flue pipes themselves that draw air into your stove, it is the affect heat has on the density of the molecules within the gases. The warmer the gas, the lighter the molecules, the more encouraged they are to rise. Reversely, the colder the gases, the heavier the molecules and the more likely they are to slump or drop back down the system. Therefore, if the molecules within the gases inside the chimney system are warmer than the molecules within the air outside the chimney system, the gases inside the flue will rise as the air outside sinks and rushes in to fill the space left by the rising warm air (put simply), thus creating the magical draw!
  • Taking the above into consideration, the greater the temperature difference between the flue gases and the air outside, the greater the draw. Simple.
  • Thirdly (but crucially), the height of the flue system affects things as the taller the system, the greater the change in pressure which also encourages a stronger draw.

So what is Spring & Autumn syndrome? This is concerned with how quickly temperatures can change around these times of year. If the temperature outside should happen to rise quickly then this can easily surpass the temperature within the home. Warm outside vs cool inside equals a reversal of the draw as air flows down the system rather than drawing up.

Should this reversal of draw occur, you will not know until you attempt to light your stove. The lighting cycle will begin but the air coming down your system will force smoke out of the stove into your living space and prevent any hot air from rising into the flue to remedy things.

So how do you avoid this situation?

Firstly, test the direction of the draw before lighting it! Even without a fire burning, there is a draw of sorts happening in your flue and there are ways to find out which direction this is flowing; by hand or is a smell of soot being pushed out of the flue?

Secondly, should the draw be in reverse, you can encourage it back up the system by artificially warming the air within the flue. Some use a hair dryer, others a blow torch.

But, here at Glowing Embers we have a top tip! Stack your fuel in reverse. Logs on the base, kindling on top and firelighters on top of this. This is a tried and tested method in our showroom because the heat produced by initially the firelighters and then the kindling is directed up into the flue and not down into the fire bed, thus warming the flue above first. You will most likely experience a little smoke at first but if stacked and controlled well, the flue should warm reasonably quickly and the stove kick into life…

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