- How should I source a supply of wood?
However well made and efficient your stove is, dry, well seasoned wood is the key to wood stoves working well. You should always order wood by length or solid measure, rather than by weight. Green or semi-seasoned wood will obviously have a high moisture content and weigh quite a bit more than seasoned wood which has dried out properly.
A solid cubic metre of fresh felled timber weighs about 1000kg, or 1 tonne, and contains up to 600kg of water. The weight will drop by up to 225kg by air drying alone. Since it is cheaper to buy in wet or semi-seasoned wood and leave it to dry out yourself for at least a year, it makes more sense to buy it by the cubic metre rather than weight. Then, apart from the first year of having your stove, you will have one load for burning and one drying.
You should always ask the timber merchant how well seasoned the wood is, how long it has been left to dry out, to give you an idea of how much longer you will need to store it for. The wood should be covered to protect from the rain, but air should be allowed to circulate around the logs.
It might be a good idea to invest in a moisture metre so that you can judge how wet the wood is. Although a log might be bone dry to the touch it can still be holding a lot of moisture.
You can buy kiln dried logs but these will be considerably more expensive.
The figures used in this section are taken with kind permission of the Forestry Commission from their leaflet entitled ‘Wood as a Fuel’.
- How do I keep the glass clear?
All the stoves we sell have an ‘air wash’ system to help keep the glass clear. Air is forced down behind the door providing a barrier against the gases of the fire, and keeping tarry deposits from blackening the glass.
However, no matter how efficient or well designed the stove is, the air wash will only work if you are burning well seasoned wood at a high enough temperature. If the wood is too wet, or if you have turned the air supply down before the fire has had the chance to reach a high enough temperature, then the stove won’t be hot enough for the air wash to work properly.
It may be that even with everything working well the glass clouds up a little once you have let the fire go out. The air wash system will clear this the next time you light the fire. However, it won’t get rid of the sticky tarry deposits that burning wet wood leaves. For these you can use spray-on Stove Glass Cleaner, which we stock.
After a while you may also need to replace the thermal rope which acts as a door seal, and which will wear down over time. If air is getting in around the door then it may interfere with the air wash system. We stock several sizes of rope and high temperature glue.
- I’m having trouble keeping the fire lit, where am I going wrong?
The first thing to check is that your wood is dry. A small log with a moisture content of just 20% still contains about 1/2 pint of water. The first stage of burning is when the water in the wood is boiled off. The wetter the wood, the longer this will take, and the longer you will have to wait for a ‘good’ fire to build up. The fire is ‘cooled’ by the process of burning the water off. The second stage of burning is when the resins in the wood are burned to produce hydrocarbon gases. If the fire hasn’t reached a sufficient temperature then the gases won’t be burned off and will be sent up the chimney to form tar. A chimney blocked with tar won’t be providing an adequate draw and is a definite fire hazard!
If you are buying kiln dried logs they will be ready to burn. If you have ordered a supply from a timber merchant ask how long the logs have been left to season. Logs should be chopped before being left to season, and should be stored under cover but with a good air supply around them. They should be stored for at the very least a year, ideally two. Dry wood should have a moisture content of no more than 20% (freshly cut wood can have as much as 90%), and you can buy a moisture meter to test this.
Another mistake people often make is to turn the air control down before the stove has reached a high enough temperature. When first lighting the stove, the air control should be opened right up to allow lots of oxygen to fan the flames. Start off with a few small, cut logs (uncut, round logs won’t take so well), on top of a bed of kindling and a couple of fire-lighters, and leave the air control open. Sometimes it also helps to leave the door ajar at first too, particularly on still days. You shouldn’t be turning the air control down until you have a good bed of burning embers which allow a log to catch light almost immediately. Even then, the air control shouldn’t be shut down too much as you are then starving the fire of oxygen and reducing the temperature of the firebox. Once the stove is burning hot enough to burn the wood efficiently there shouldn’t really be visible smoke coming from the chimney, so a good test might be to pop outside and have a look. If you’ve turned the air control down too much then you’ll see smoke. Alternatively, a stove pipe thermometer can be used to make sure you’re burning the stove within the correct temperature range, which should be somewhere between 300˚c and 500˚F.
You should be waiting until the current load of wood has burned down to hot embers before introducing more logs as the process of burning the water from the new load will cool the fire. Open up the air control when re-fuelling, and then only turn it down once the fire is burning well again.
- How often should the chimney be swept?
The chimney should be swept at least once a year. If the stove is used a lot it might be wise to have it swept twice a year. If you’re burning wet wood and / or burning the stove under capacity (neither of which you should be doing by the way!), then you should definitely be getting the chimney swept more often!
In between sweeps it’s a good idea to use a chimney cleaning product such as ‘Flue Free Chimney Cleaner’ from ‘Hotspot’, which you sprinkle on the fire to help break up the tar in the chimney. This means that the chimney sweep is able to do a more thorough job as the brushes are less likely to just glide past compacted tar.
- Will the stove stay lit over night?
If you’d like the stove to stay alight over night it’s best to choose a multifuel and burn solid fuel rather than wood.
The stove will only stay lit throughout the night with wood if the air controls are turned right down. This causes the fire to burn very slowly by starving it of oxygen, and means that the stove isn’t reaching the temperatures needed to burn the wood effectively. During the burning process, the resins in the wood boil to form hydrocarbon gases and the stove needs to be at a high enough temperature to burn these. If this isn’t achieved then the boiling resins will be sent up the flue and will condense on the chimney walls, becoming tar, and reducing the life of your liner. You’ll also be wasting approximately 1/3 of the energy in the log.
It seems so much more convenient to be able to just leave the stove slumbering away all night, but there is a cost to the longevity of the liner and stove if you do this. You wouldn’t leave your central heating on all night, so why waste wood by burning it ineffectually in a room you’re not using? If you have dry, well seasoned wood, and have kindling and fire lighters then it’s easy to re-light the stove in the morning and have a good fire burning quickly.
If you do use the stove this way, it’s best to have it swept at least twice a year, and to use a chimney cleaning product such as ‘Flue Free’ granules from ‘Hotspot’.
- Which parts of the stove may need replacing over time?
Stoves are guaranteed for a certain amount of time which varies between manufacturers. However, there are certain parts which won’t be included in the warranty, and which you should expect to replace over the lifetime of the stove.
These are the glass, the glass seals, the rope in the door, the firebricks which line the stove, and sometimes the baffle. How soon you need to replace these things is really down to how you run the stove. The glass, while heat proof, is breakable like any glass. So watch out for logs falling against it or slamming the door while a log is sticking out, and watch what you’re doing with the poker! The rope seals in the door wear down eventually and can then let air in which makes it more difficult to control the fire and stops the air wash working properly.
The firebricks can crack over time. If the break is clean then you can carry on lighting fires, but the brick will need replacing if the sides of the stove have been exposed. Running the stove too hot for extended periods will reduce the life of the firebricks, as will throwing logs onto the fire or hitting the bricks with a poker.
- My chimney sweep tells me there’s a lot of tar in the chimney, what’s causing this?
Even the best stove, run with the best dry wood will let boiling resins up the chimney, they then condense to form tar. The warmer the chimney, the less tar will form. If the chimney is not well insulated, and therefore cold, then the hot gases will hit the cold walls of the chimney and condense to form tar. Eventually the flue will get saturated in foul smelling tar which is a fire hazard. In some cases tar stains will start to appear in the loft area and gradually get lower, appearing on the upstairs chimney breasts.
Insulated chimneys are therefore essential for burning wood. If a stove has been fitted with a stainless steel liner and backfilled with vermiculite (our usual method) then this will be a suitably insulated chimney. However, clay liners which are often used in newly built chimneys, take longer to warm up, and may need sweeping more often. An unlined brick chimney, which is likely to be fairly large internally, should really be lined when attaching a stove as it’s very difficult if not impossible to warm up sufficiently.
The other cause of a tarred up chimney, which is likely to be the problem if you have a properly insulated liner, is burning wet wood. Ideally your wood should have a moisture content of no more than 20%, and a moisture meter can be used to determine this. Although the wood may be dry to the touch, it can be holding a lot of water internally. It’s important to ensure you have a good supply of dry wood, or make plans to split and store un-seasoned wood under cover the season before you need it.
Even if you have dry wood, it will still contain a certain amount of water. A small log with a moisture content of only 20% will still contain over 1/2 pint of water. You therefore need to make sure that you are burning the wood at a high enough temperature to boil the water content off quickly enough. A stove pipe thermometer will help to determine this.
- Is it okay to leave the stove doors open?
Please don’t! Some people say you can, but why on earth would you spend the money on a stove, only to waste all the benefits of it by running it like an open fire? It’s a waste of heat and money and may also void your guarantee with the manufacturer.
If you leave the doors open you are making the stove uncontrollable and letting lots of air rush up the chimney, taking all the lovely heat with it! The efficiency of the stove will therefore plummet. As you won’t have any control over how long the wood burns for, you’ll also be getting through a lot more logs. The only time you may have to leave the door open would be when you are lighting the stove and you need a lot of air to get the fire going quickly, and even then you would only need to leave it slightly ajar.
There are some stove manufacturers who have made a real effort to ensure that as much of the fire is seen as possible, and with air wash systems to keep the glass clean, you’ll have a clear, uninterrupted view of the flames.
If you would really rather have an open fire, then a nice compromise is a wood or multi-fuel canopied fire from Dovre. These fires have doors which can be drawn right back. Visit www.dovre.co.uk to take a look.