During the Spring and Autumn months, temperatures can rise suddenly making it a lot warmer outside than inside. When this happens, it can sometimes lead to what we in the stove industry call Spring / Autumn Chimney Syndrome.
Spring / Autumn Syndrome is when the air in the chimney begins operating in reverse to its normal flow pattern. The most obvious sign of this only comes when lighting your stove during these seasons due to the changeable weather conditions.
Because of the warmer temperature outside, your house can feel colder than it is, and the desire to light your lovely woodburning stove to keep yourself warm and cosy – even though it’s mid-April or early September – gets too much to bear. You have put on your extra jumper and pair of cosy socks – but it is no use, only the heat from your fire will make your home feel as warm as the temperature outside.
Sometimes Spring / Autumn Syndrome can be seen by the stove itself not lighting how it would normally.
If sufficient air is coming down the chimney or flue in reverse, then the stove will begin to light but spill smoke through what are normally air inlets out into the room.
The stove can continue to do this for some time, where normally the heat produced in lighting your stove travels up the chimney to aid the draught, when the chimney has a reverse air flow the heat from fire has no chance to travel up the flue, warm the chimney and operate normally.
Most prevalent if you have an external flue, twin-wall system or block-built chimney, the dense cold air within the chimney can act as a plug in the flue.
Remember it is not the stove's job to push the air up the chimney, but the chimney's job to pull air through the stove.
How to prevent Spring / Autumn Syndrome:
The best way to combat this is a lighting method detailed below in an easy 10-step process which helps get heat into the chimney gradually so as the fire increases slowly the smoke will then be drawn up the flue system.
Inverted / Upside Down Lighting Method:
1 – Make sure the grate is not covered in ash or chunky remnants of your last fire. This is so the air can pass easily through the grate up into the bed of the fire.
Set the controls on your stove to the lighting position as detailed in the instruction manual.
2 – Place two small split logs (logs should always have a moisture level of less than 20%) across the fire bed making sure that you leave some of the holes in the grate uncovered.
3 – Create your normal pyre of kindling on these two split logs (as pictured) with firelighters interlaced within the pyre to allow air to pass easily through the kindling tower which enables a quick and clean lighting process.
4 – Light the firelighters and close the door on the stove. The fire will slowly increase in size and heat, warming the flue gradually without producing copious amounts of smoke. As the fire grows, it heats the chamber and flue, allowing the flue draught to start to establish removing any smoke that might have built up within the chamber during this step.
5 – Leave the stove alone and in about 5-10 minutes, once the fire has established, you can move the air controls from the lighting position and leave the secondary air controls completely open.
6 – Again you can leave the stove to continue burning with the secondary air control fully open, and as the kindling falls between the logs below it then lights these slowly. Once these logs are burning well, then the air controls can be adjusted to the usual place for when you are using your stove. The stove will then continue to burn the logs at a controlled rate and output.
7 – You don’t have to rush to reload your stove as soon as the flames stop. The heat from your stove will continue while the logs are still burning. In doing this you are ensuring that all the volatile gases are burned from the wood that causes smoke so that when you come to re-fuel the stove no smoke will escape into the room.
8 – When you are just left with glowing crunchy looking cubes of charcoal on the fire bed – This doesn’t always look the most appealing, but it is the best way to refuel your stove with minimum leakage and spillage while the door is open for reloading - you are ready to reload your stove.
9 – Set the air controls to fully open
Remember – ALWAYS wear a heatproof glove (normally supplied with the stove) when re-fuelling your stove.
10 – Open the door – only a crack – this allows the pressure to equalise between the stove chamber and your room. If you pull it straight open, you run the risk of the change in air pressure causing fine ash or smoke to be pulled into the room.
After about 5 seconds open the door fully and load the logs as per the manual for their load rates. Once these logs have been lit and fire has begun establishing again you can return the air controls to their previous operating positions and regulate the burn level through the secondary air control.
TOP TIP – Have your new log/logs close to hand so that the door is open for the least amount of time possible.