Spring chimney maintenance
Now that spring has arrived and as the weather warms up you will soon be leaving the fire or wood burner alone until autumn. Now is a good time to do some chimney maintenance and stove maintenance so that it is in good condition for autumn.
As you will be using the fire less now, and possibly not at all until the autumn, it is time to think about having your chimney swept. Wood stoves and fires have deposits of soot and creosote that are flammable and corrosive. Removing the products of combustion at the end of the burning season makes sense from both a safety and maintenance perspective. With a brick flue soot and water makes a corrosive slurry that attacks brickwork and mortar. If you have a stainless steel liner it makes sense to remove the soot now rather than leaving it in the liner to absorb moisture and become a tarry substance that may drip down the flue.
Spring is also a good time to identify any maintenance that needs doing on your flue or stove so you can have it done before autumn when you need to use it.
Closing down your wood burning stove for summer
Refer to your stove’s manual for instructions on how to take out the baffle or throat plate, grate and fire bricks. Be careful with the bricks as these can become fragile after being in use. Clean out all the ash and soot and use a wire brush to remove soot from the inside of the stove. Clean the grate with a wire brush and inspect it to check for any damage, replace any parts that need changing. Clean the stove glass and check the rope seals, change any that are damaged. If your stove has any marks or rust areas, you can clean these up with wire wool or sandpaper and repaint your stove – remember to use heat proof stove paint.
Seasoning your own wood
If you are planning to season wood yourself, you will need a suitable log store located outside in a location that allows free flow of air around and through the woodpile to help season the wood. Ideally your log store will have a roof to keep the rain off, but you could simply put a tarpaulin over the woodpile providing it is secured (or it will probably end up in your neighbours garden if it gets windy). You will also want to keep the logs off the ground, if you don’t have a purpose built log store, then you could use pallets to stack it on.
If you are stacking your log store with freshly cut logs you should ensure that they are split into suitable sized pieces – 200 – 300mm long and 50 – 150mm in diameter (any fully round logs should be split in half so that they dry out more easily). Splitting larger logs down will allow the middle of the log to dry out and ensure that they season quicker than when left whole as moisture can evaporate along the length of the exposed wood rather than just from the ends.
How long will it take? Well there are a lot of variables at play, the type of wood, how recently it was felled, what its current water content is etc. What you are looking to achieve is moisture content of less than 20%. In some cases this could take a year or as much as 3 years. The only accurate way of knowing the moisture content is to buy a moisture meter.
Buying seasoned logs
Many suppliers sell seasoned logs but you need to be clear that unless they state the moisture content is below 20% you will still need to store these until they are dry enough to burn. If you don’t have a moisture meter there are a few things you can do to assess how seasoned the wood is.
- Examine the ends of the logs, with seasoned wood you should see small cracks in the end grain of the timber, these are caused when the ends dry out
- Tap 2 logs together, you should hear a hollow sound if seasoned, a dull sound indicates a high water content.
- Very well seasoned logs may start to lose their original colour and start to go a grey colour.
Open fire versus Wood burning stove
Lots of people like the idea of a roaring log fire in winter, whether in an open fire of wood burning stove. With rising gas and electricity prices the option idea of heating your home with an open fire or log burning stove is also becoming increasingly appealing.
Perhaps you are considering opening up an old fireplace or installing a wood burning stove in your property. One of the things that may influence your choice is the initial cost involved, particularly if you are working on a tight budget.
Providing your existing chimney is sound (you should have it tested to ensure this). Fitting an open fire has lower initial costs than fitting a stove. The main costs will be to create a fire opening with a fireback, hearth and grate. You may also need to fit an appropriate chimney pot or cowl if you do not have a solid fuel approved one already.
If you are planning to install a wood burning stove then in addition to the cost of opening up the fire place there is the cost of the stove itself, along with a stainless steel flue liner if you are planning to line the chimney (if not you should ensure that it is sound and not leaking into your property or any neighbouring property) and the hearth and fireplace.
Clearly the cost of installing a wood burning or multi-fuel stove is going to be higher than the cost of opening up a chimney for an open fire and this may influence your choice. However, you should consider the long term cost of using the appliance. Typically an open fire operates at around 30-35% efficiency so an awful lot of heat goes straight up the chimney and out of your home. So in real terms for every 10 kilowatts of fuel you burn around 7kw is wasted.
Wood burning stoves are much more efficient with some manufacturers claiming figures of nearly 90% efficiency therefore over the longer term you will save money because you will be using less fuel than you would on an open fire.
The importance of burning dry wood
With any wood fuel and firewood logs in particular, the most important thing to consider is the moisture content. When burning wood some of the calorific value of the wood is used to drive off the water content within the log.
When freshly cut a tree can have a moisture content anywhere between 40 to 60% depending on the species of wood and time of year the tree was felled. To put this into perspective 10kg of unseasoned wood could contain as much as 6 litres of water. Ideally wood should have a water content of 20% or less.
When burning logs, the moisture is driven off and forms steam, this steam can condense in the flue system and react with the volatile organic compounds within the fuel to form sticky deposits (tar and creosote).
Over time these can block the flue and just as importantly these deposits contain unburnt fuel and therefore increase the risk of a chimney fire. If your stove is connected to a stainless steel flue system (flexible liner or twin wall) these deposits are corrosive and will attack the liner.
This is why it is important to ensure that you only burn seasoned wood and have your chimney swept regularly.
So in summary – make sure you only burn seasoned or kiln dried wood with a moisture content of less than 20% (a good investment would be a moisture meter so that you can check the moisture content yourself) and ensure you get a chimney sweep to sweep your flue.
Lighting your Stove
Whilst there are various methods of lighting your fire and there are no right and wrong ones providing you manage to get it going, my preferred method is top down burning. It rarely fails to work for me and once set up it needs very little attention unlike methods where you build a tepee of kindling and then add more kindling and larger pieces as it gets going.
I start off with two pieces of split logs about 10-15cm across at the ends and wedge shaped. These are place slightly apart to form a vee in the middle. I then place two larger pieces of kindling at right angles to form a bridge over the gap, on top of this further pieces of kindling are built up like jenga blocks but with gaps between them. On the top of this I place several pieces of scrunched up newspaper and further newspaper around the side.
Set the stove vents for wood burning (if it is a multi-fuel stove) according to your stove instructions, light the newspaper and leave the stove door open about 10mm. You should find that the newspaper sets light to the kindling and the burning newspaper and small kindling starts to warm the flue and create a draught which helps the fire light.
As the kindling starts to burn it will light the pieces underneath and eventually fall into the vee section between the logs setting these alight. This should mean that you do not need to do anything apart from keeping an eye on things to make sure it all lights ok.
You may need to add more kindling if you didn’t have enough on to start with, and occasionally when lighting the newspaper you may need to add a few more sheets but apart from that it should light fine.
Happy burning, and remember if you haven’t had your chimney swept this year, then now is the time to get your local Guild of Master Chimney Sweeps, accredited sweep in. Please note this is the busiest time of year so next year book early!