Wood Fire Care & Tips

Listed below are tips and advice on caring for and getting the most out of your Kent wood fire. If you still have a query, please call our helpful Customer Services team on NZ Freephone 0800 161 161 or email us for assistance.

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Efficient Kent Wood Fire Operation

  • What is the best way to safely and efficiently operate a wood fire?

    Operating Kent wood fires is straightforward, with a little bit of advice, correct use of combustibles and practice, Kent wood fires are easy to light and control.

    Lighting

    Ensure the air control knob is fully open. Place several pieces of crumpled newspaper in the base of the firebox, and criss-cross with 8-10 pieces of dry split kindling. Stack several pieces of dry split firewood approximately 40-50mm in size on top of the kindling. Ignite the paper and partly close the door. Let the fire establish itself for a few minutes, then open the door and add some more pieces of wood. Close the door, but leave the air control fully open until the wood is well alight and burning brightly. Do not leave the fire unattended during this process. Please note that it may be necessary in some cases to leave the door ajar for longer periods and use more small kindling in order to establish enough heat to warm up the flue. Only when the flue is sufficiently warm to create the necessary draft to maintain the fire may the door be fully closed. It may take trial and error to find a lighting procedure that suits your situation.

    Normal operation

    Once the fire is well established and the door can be fully closed, the output can be regulated by the amount of wood that is used. To reload the fire, open the air control fully, if this has been turned down, and open the door. Note that the fire burns hottest at the front of the firebox and so there may be unburnt wood at the back when it comes time to reload. This is normal. Rake through the coals to move any unburnt wood forward and then place the desired amount of wood into the firebox. Close the door. Operate the fire for 10-15 minutes with the air control fully open to allow the fire to fully establish again, before attempting to adjust the air control.

    Don’t leave your wood fire unattended with the door open. Keep the door closed during operation to avoid developing excessively high temperatures that may damage the wood fire and flue system. Avoid slamming the door and don’t allow anything to strike the glass.

    NEVER use gasoline, lighter fluids, kerosene or similar liquids to start or “freshen-up” a fire. Keep all such substances well away from the wood fire while it is in use to avoid risk of explosion.

    Do not operate the wood fire too fiercely when new. Allow a bed of ash to build up with several small fires first.

    Cleaning out the wood fire

    Your wood fire should require a minimum of cleaning out. If the wood fire is operated correctly according to the instructions most of the ash will be consumed by later fires and a bed of ash will be maintained that does not build up to any great extent. If you find that you are having to clean out ashes every day or so, it indicates that the wood fire is not being operated correctly. Excessively wet or unseasoned wood is being used, or the air control is being turned down too much. This will also contribute to higher levels of ash left in the wood fire.

    Don’t clean out the firebox completely. Leave at least 25mm of ash in the bottom of the firebox after cleaning. These ashes in the bottom of the wood fire assist the burning process, by insulating the firebox and allowing air circulation under the fire bed. When emptying ashes use a metal container with a tight fitting lid. Do not use this container for any other purpose.

    The closed container of ashes should immediately be taken outdoors to a location well away from any combustible materials, pending final disposal. If the ashes are to be disposed of by burial in the garden or otherwise locally dispersed, they should be retained in the container until they are completely extinguished and cold. This may take several days. Wood treated with chemicals will leave toxic residues in the ash. These ashes must be disposed of so they cannot contaminate the environment in any way. We emphasise that this type of wood should not be used in your wood fire.

    In the event of a flue fire

    In the event of a build-up of creosote or soot igniting in the flue (usually from burning incorrect wood), close the air control fully. This will minimise the amount of air that can get into the burning flue to help extinguish the fire. Prepare occupants of the house for evacuation. Contact the Fire Department. While waiting for the Fire Department, watch out for ignition of adjacent combustibles from the over-heated flue, hot embers, or sparks escaping from the flue.

    A flue system that has been properly installed will sustain minimal damage from such an event and cause minimal structural harm to the building.

    We recommend that you get your flue professionally cleaned every 12 months before the start of the heating season or more regularly if required.

  • How do I get the most out of fire wood?

    Wood is a renewable source of solid energy. Unlike other forms of solid energy such as coal, it is not a nett producer of carbon dioxide, a gas that some people believe is contributing to global warming or other detrimental environmental effects. Burning wood in a wood fire produces no more CO² than allowing the wood to rot in the forest.

    Wood is a combination of solid and gaseous components. In order to burn properly, both components must be exposed to proper conditions. "Good wood" is a major contributing factor to the performance of a fire.

    The solid component, basically the charcoal content, is the easiest to handle. Most controlled combustion wood firescan extract the heat from this quite readily. This charcoal component generally yields about 50% of the potential heating value of the wood. The gaseous components are harder to burn properly. If not burned properly, these gases can leave the fire as smoke, creosote and particles. Our engineers are now designing fires that extract as much of the usable heat out from the gases emitted by the fuel as possible and, by doing this,so limit the amount of emissions from the flue.

    Use dry wood

    The most important thing you can do to operate your wood fire correctly is to use the correct fuel.

    Most types of seasoned natural wood may be used in your wood fire, but do not use chemically treated wood or wood with high sap content or salt-impregnated wood, such as driftwood. These may corrode the components of the wood fire and flue system. These materials may also emit toxic gases when burnt and will leave toxic residues in the ash and flue.

    The moisture content of the wood affects the performance of the wood fire greatly. Well-dried wood is the best thing you can give your wood fire. This should be seasoned for at least 9-15 months to lower the moisture content to less than 25%. Use a Kent Moisture Gauge to measure the moisture content to make sure you are getting the greatest energy from your wood.

    Kent wood fires are designed to burn soft wood. Both New Zealand softwoods and hardwoods burn well. Most hardwoods are denser than softwoods and will burn longer for an equal sized piece. All natural woods have approximately the same energy content per unit of dry weight. If hard wood is used as a fuel we recommend that it is mixed piece for piece with soft wood.

    Poorly seasoned wood means more work. You will be carrying heavier loads, getting less output per load and your glass door is more likely to get covered in creosote. A wet piece of wood placed in a hot fire will burn but will spit and splutter, even causing water and creosote to be splattered on the glass. While these deposits will burn off, some of the potential performance of your wood fire will be lost. If you can see moisture bubbling off the ends of logs placed in a heater with a good hot ember bed, your wood is too wet.

    Fossil fuels such as coal are not suitable. Do not burn garbage, or large quantities of paper, cardboard or similar materials. Do not use wood reclaimed from marshes or swamps. Do not use driftwood.

    Use the proper amount of wood

    As previously discussed, the best way to see if your wood fire is working properly is by the appearance of the flames. This means that the amount of wood that you use is important.

    Wood is stored energy. If you want a large amount of heat to be produced by your fire, you should use a large amount of wood. If you want less energy, use less wood.

    IN NORMAL OPERATION, YOU SHOULD NOT ATTEMPT TO REGULATE THE OUTPUT OF THE WOOD FIRE BY USING THE AIR CONTROL, BUT RATHER YOU SHOULD ADJUST THE AMOUNT OF FUEL USED.

    On cold days, and when you need a large heat output from your wood fire, load the firebox fully after establishing the fire and you will be comfortable and warm. When comfort levels are reached, subsequent loading should be lesser amounts to maintain the heat level. Optimum efficiency will be achieved when you add only the amount of wood needed until the next time you are free to refuel. Many fires will even burn one log at a time once the stove has been well heated up and a good ember bed exists.

    On warmer days, just burn smaller fires (less wood). Make sure you keep the air setting high enough for a clean burn. The cleanest burns will occur when large pieces of wood are placed on a good bed of glowing coals and the wood fire itself is at a high temperature.

    Use wood of different sizes and shapes to promote good air flow around the pieces. You can load up to 2/3 the height of the firebox chamber. Avoid over-firing. If the top of the firebox is glowing, you are over-firing. This will damage the wood fire. Store your ready-to-use firewood well away from the wood fire while it is in use.

    Preparing/storing wood for burning

    To get the best possible heating value out of your wood, you will need to season it properly. This is best accomplished by planning ahead. Wood can take up to two years to dry out fully. A fresh cut tree can be up to 50% water, which means half of the weight of the log you are carrying is of no use to you. If stored well, after 12 months of seasoning, the moisture content may have dropped to between 10 and 20%, which will be ideal for getting the best performance out of your wood and fire.

    The shorter the piece of wood and the greater the surface area exposed to the air, the faster it will dry. A good way to prepare your wood is to cut it to heater-sized lengths and split any pieces over 150mm (6 inches) diameter as soon as the tree is felled.

  • What are the different heating costs between power, gas, LPG, pellets and wood?

    The cost of providing heat (which is heat energy transformed from fuels) is determined by the fuel type, fuel quality, fuel cost and efficiency of the appliance used to make the heat.

    Using industry data we have estimated the differences for you here. We have used the average energy efficiencies of appliances, the net calorific value (CV) of the fuels (the remaining energy available after any exhaust gases have been flued), and excluded standing/rental charges. The following are heating costs based on the fuel used and the type of appliance, the actual cost of the appliance has not been included. Generally speaking the more you pay for an appliance the cheaper it will cost to heat a whole home on a room-by-room basis.

    So you can compare the cost of heating a lounge, we have summarised different fuel costs and appliance efficiencies below:

    Heat Pump Power = 22 c/kWh Heat Energy (100-300% ee) 7.3 - 22 c/kWh depending on the selected unit.

    Next lowest is natural gas, as one unit of gas is low in cost and the efficiency of most appliances are around 86%. NG = 8.8c/kWh Heat Energy (85% ee) 7.5c/kWh

    Wood Pellets = 10.5c/kWh Heat Energy (90% ee) 18GJ/t or 5000kWh/t, $475/tonne, 8% Moisture Content, 650kg/m³ Density, $475/5000 = 9.5c/kWh.

    Pine Firewood = 11.5c/kWh Heat Energy (65% ee) 15.5GJ/t or 4300kWh/t, $320/tonne, 20% Moisture Content, 250 kg/m3 Density, $320/4300 = 7.5c/kWh.

    LPG = 20.50c/kWh Heat Energy (85% ee) 46MJ/kg or 12.8kWh/kg, 45kg cyl = 576kWh, 45kg cost = $100, $100/576 = 17.4c/kWh

    Power used directly by 100% resistant electric heaters (oil-filled, radiant, convector etc) is the most expensive, simply due to the high unit cost of power. These are the cheapest heaters to buy, hence they are still used as a compromise when a home has not been installed with proper central heating.

    Power = 22c/kWh Heat Energy (100% ee) 22c/kWh

  • Can I control the amount of heat produced by a wood fire?

    This is determined by the amount and quality of wood burned, the size of the logs and the fire design (efficiency, size of the fire box and the airflow controls). Airflow controls affect the rate at which the wood burns so some control is offered, however this also leads to choked air supply and this is when CO² emissions and particulates are at their highest.

    Burning the right amount of (quality) wood in the firebox is key.

    Example: Say a firebox can take 7kgs of wood. If dry softwood is used, the CV will be 18Mj/kg and this will provide 126Mj of energy at one maximum time. Divide by 3.6 to give kW = 35kW. Factor in the fires efficiency (68.70%) you end up with 24kW of heat available or 3.4kW per kg of dry soft wood.

    If you only half-fill the firebox then you get half of the above = 12kW (only burning 3.5 kg of wood). If the heat from your fire is used for a lounge only (not throughout the house) and you want to only produce 6kW of heat then the 7kg firebox should only be a quarter full (less than 2kgs of wood). A smaller firebox of 4kg will only be half full to provide 6kW of heat.

  • What is the right way to load wood in a fire?

    Once you have ensured the wood is the right size and has low moisture content, consult your fire’s operating instructions. These will advise if the fire is best loaded in a front to back or side to side method. Loading methods can affect the effectiveness of the fire to produce low emission levels. Size your fire wood so it fits the fire box in the correct configuration.

  • What is the best way to maintain a wood fire?

    Kent wood fires require minimal maintenance, and will hold their performance and finish for a long time with just a little attention.

    Cleaning

    The exterior surfaces of the wood fire should be cleaned when needed with a damp cloth and non-abrasive cleaner. Use of caustic or abrasive cleaners, such as most Spray n' Wipe type products, will damage the finish on the wood fire.

    If, due to continued burning at low temperature, the door glass is dirty, use a paper towel moistened with water and dipped in the cold ashes from the fire to lightly scrub the inside of the glass. Remember that a properly operated wood fire will keep the glass clean by itself.

    Door Replacement

    In the unlikely event that your door glass should break, obtain a complete replacement door from your Kent retailer. Use of incorrect glass may cause injury or property damage. Never operate the wood fire with a broken door glass or with the door missing.

    Door Sealing

    It is important to the correct operation of the wood fire that the door is sealing properly. If the door is loose or too tight, reset the catch by adjusting and re-tightening the internal nut. If the seal is damaged, obtain the correct replacement part from your Kent retailer.

    Lubrication

    The door hinges, door handle spindle and air slide mechanism should be lubricated when required with a suitable high temperature grease. Do not use too much as this can melt and drop down onto the hearth staining it.

    Baffle Plate and Air Tube

    The baffle plate and air tubes should be inspected monthly during the heating season for any signs of damage or deterioration such as extreme distortion. If parts require replacement refer to the Assembly Instructions for removal and replacement.

    Other maintenance

    Any other maintenance required should be carried out by qualified service staff. Please consult your Kent retailer for local service people. Any replacement parts used must be original Kent parts. The wood fire should not be modified in any way except in accordance with written instructions supplied by Kent.

    Annual servicing by qualified service people is recommended as a minimum to ensure safe operation of your fire.

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