The title asks the question “are wood stoves safe?”, and I will attempt to provide you with some information related to that question and hopefully answer it for you.
First of all, there are wood stoves and there are wood stoves. Actually there are inserts, factory built fireplaces, pellet stoves and all manner of wood burning appliances. I have cleaned chimneys in most of them, and inspected pretty much all the styles over the years.
What is the biggest difference in any wood burning appliance – or one from another. Well to make it easier, lets compare apples with apples or wood stoves with wood stoves. Since the title says wood stove, we will stick with that.
There are old wood stoves build in factories, new wood stoves built in factories and even some home made or locally fabricated stoves. Each is different, partially on rules in place at the time and partially the knowledge, experience and research put into the design. Generally speaking all things being equal a factory built stove is of a safe design when used properly. The companies must follow strict rules and guidelines in their design and test for clearance requirements and emission levels. Now having said that, there are some really old factory built stoves with no clearance requirements shown.
However, there are also installation codes (B365), fire code and building codes to be aware of as there may be implications and rulings in each of these which can impact your wood stove.
Any wood stove will require clearances, this is to ensure heat produced by the stove does not cause combustion of nearby combustibles. The clearances required are defined by the manufacturer during a rigorous testing process or if not tested by CSA B365 Code.
The first step in keeping your stove safe is ensuring it meets every one of these clearance requirements at all times (even or perhaps especially movable combustibles such as piles of wood, furniture, newspaper, etc.).
If you need to have stove closer than clearances allow, there are possible solutions by using shielding materials as defined in CSA B365.
Next lets look at the chimney. The chimney must be either a factory built, tested and certified chimney or a masonry chimney which complies with the local building code. Single wall brick chimneys of yesteryear are something which generally should have a liner inside to protect against inevitable disaster. A lot of the older homes in the Midland and Penetanguishene area have double brick chimneys, these often have cracked mortar and loose or missing bricks. Clay tiles inside or even more preferable steel liners are a great solution to improve safety of these old chimneys. If you have room an insulated steel liner is the absolute best solution in these old chimneys!
Often for newer chimneys I see the factory built or 650C chimneys. These chimneys are generally very good, however I have seen some with terrible creosote build up and even some with discolouration of the outside surface which would indicate breakdown of the insulation in the walls. This is why when I do WETT inspection, I prefer a Level 2 inspection – inspect inside the chimney – look in the attic when possible.
Check your wood stove is using the flue pipe or chimney by itself. While there are some conditions where two appliances can share the same flue pipe, generally speaking this is a bad idea for a few reasons.
- sometimes flue is not large enough to provide proper use of the two appliances at full capacity
- the flue can get dirtier much faster and require much more frequent cleansing – I have one customer who needs three cleanings a year and in the middle of winter is not nice for me or the occupants (as stoves much be cold)
- sharing with fossil fuel appliances (such as stove oil) is just plain nasty and makes a terrible sticky nasty creosote
Bottom line ensure you chimney meets proper code and that it is in good condition. When you get a WETT inspection – believe it or not – the LEVEL 1 inspectors generally do not check for condition of chimney! They are neither trained nor equipped to do this task.
Vent pipes or flue pipes. A critical piece and where the majority, perhaps 90%, of all chimney fires begin. The vent pipes or flue pipes are not chimneys, they are stove pipes (with either a single layer of steel – single way – or two layers with an air space – double wall). They connect the stove to the chimney. Generally the shorter the vent pipe the better, and it can have no more than 2 – 90 degree elbows in the run, I prefer to use 45 degree elbows where possible as two 45 degree elbows offer less resistance than a single 90. The stove pipes must be installed with the crimped ends facing down toward the stove, this allows any water to remain inside. They also must have a minimum of 3 screws designed to hold stove pipe at each joint. While single wall pipe is allowed by the code, I would never install it myself, and have never done so. In fact I have replaced a lot of single wall with double wall in years gone past. The clearances are better with double wall pipe and overall it is just generally safer. Stove pipe clearance, even with double wall pipe, must be closely followed. Stove pipe must NEVER pass through an interior wall, floor or ceiling. (although I have seen from years gone by where they passed through walls and had spacers to keep away from combustible materials – not permitted today) Stove pipes are permitted to pass through an exterior wall, if necessary, however there must be a minimum 18 inches clearance to combustibles on all sides – there are steel thimbles designed to accomplish this task.
Okay we have covered the easy stuff. Now the operation and maintenance. Yes the biggest part of safe burning of a wood stove is YOU! They require proper use and proper regular maintenance.
- use proper fuel – dry hardwood is best. Maple, beech, ash, oak are all good. Wood should be cut, split and air dried for a year prior to burning. Well seasoned hardwood will show cracks in the ends.
- Clean regularly – at least once a year. Don’t bother with the chemical cleaners.
- Avoid creosote buildup – a highly combustible material that clings to the chimney and vent pipe walls. Older stoves are much more prone to creosote buildup as they do not have the secondary burn phase which will burn the combustible particles in the flue gases, which later condense on the cooler walls and form creosote.
- Creosote can be either a stickily messy runny almost liquid material or;
- a black flaky almost dust like material or;
- a hard glazed shiny tar like material that is almost impossible to remove with help form a chimney sweep. This is the hardest to get off and is going to cost the most when a chimney sweep arrives as it takes them a lot more effort to get off as well.
- Never burn anything other than natural firewood in the wood stove – no building material or construction wood, no cardboard, no paper, no plastic or Styrofoam.
- Read the owners manual and burn according to stove design.
- Let fires burn down before adding more wood, do not open door in middle of burn and throw another stick of wood onto the fire.
- Regularly remove burnt ash from woodstove and store outdoors.
The operation of a wood stove in a safe manner comes down to :
- proper installation and code compliance
- use of proper components – chimney, vent pipe, stove, ember pad, etc. throughout the entire installation
- proper maintenance and cleaning on regular basis
- knowledgeable use of stove in burning properly using the proper fuel
Here is a good resource to download and read on wood burning.
Wood Burning Stove Safety Tips