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Why is my Pyroclassic using more wood than I thought it would?
This could be because the loading door is not airtight. Check the gasket - if you need a replacement, you can purchase one from our Parts Shop.
Another common cause of this is incorrect operation. Remember the Pyroclassic IV's significant heat storage capacity. Add logs less often and burn fuel further back in the fire chamber.
Lastly, this can happen if the Turboslide is being left open for long periods. If this is the case, download our Operating Instructions and read about how to use it correctly.
What wood should I be using?
DRY. This means a maximum of 25% moisture content but ideally under 18% if possible.
Do not burn any wood which has been treated as this will release poisonous gases and dioxins. Do not use any driftwood as the salt content can cause irreparable damage to the ceramic cylinder and metal components. Younger softwoods and timber which has a higher moisture content will produce a greater volume of creosote and soot than dry, well seasoned hardwood.
Logs should be approximately 100mm - 120mm in diameter by around 300mm - 400mm long.
Dry wood is a must. To get the heat out of wood the fuel must pass through several stages. Firstly, free water that is not chemically bound with the wood is driven off – even wood at 20% moisture content still has to get rid of 2 litres of water for every 10 kilograms of wood. In the second stage the wood breaks down into the volatile gases, liquids and charcoal. Finally, the charcoal is also gasified, burning with a very short flame close to the char surface that appears to glow. In wood stoves all stages proceed simultaneously.
Wood is the most prolific worldwide, solar embedded, carbon sequestered energy source which is renewable in a human lifetime. It will provide energy when the sun is not shining and the wind is not blowing, when the outside temperature is above or way below freezing and when the electricity is not coming out of that little hole in the wall. If the abundant, worldwide timber resource is managed correctly it is the most sustainable, environmentally safe, renewable, resource we have and it has sustained mankind for centuries, providing us with warmth for the space we live in, warm water to clean with and the ability to cook food.
With the discovery of more energy intensive and easily transportable fossil fuels, wood was relegated to a lowly place in the order of preference and although it is bulky to transport it is the safest as it does not need a specially built pipeline, it won't suddenly explode or cause devastating marine pollution and with almost no refining can be used in its raw state. The closer it is used to the place where it has grown makes this an even more environmentally friendly product.
Most designer wood burners catering to aesthetic demands totally disregard the thermal conductivity of wood. Microscopic examination of wood shows the channels which carry the liquid nutrients up and down the tree; consequently the properties of wood are very different along the grain than across it. Heat moves along the grain about fifteen times faster than across it, therefore, solid wood across the grain does not conduct heat and is an effective insulator meaning it does not readily burn.
When a fire is lit, even by rubbing two sticks together, the gasification process starts and it is the combustion of these gases with air that produce heat which we see as flames and smoke. When heat cannot penetrate wood easily, i.e. across the grain, the volatiles given off are not rich enough nor hot enough to burn efficiently. Efficiency apparently is not a consideration in such panoramic appliances.
This is getting to the really nerdy bit now...
Burning of the volatile gases delivers over 60% of the heat stored in the original log but few heaters can recover the major portion of this heat as the volatiles must be over 600°C and mixed with hot oxygen to burn them. Now these are difficult conditions to meet and here’s why: if the main air supply comes from under or around the burning logs, the glowing char consumes all of the oxygen - it takes only 5cms of glowing char to consume all the available oxygen. At that point, incomplete combustion continues as characterised by increased carbon monoxide and tars which mostly go up the chimney where the unburnt volatiles deposit on the flue walls as a highly flammable, gummy substance known as creosote. It is wrong to introduce cold secondary air above the fuel as it cools the gases below their ignition temperature and now they won’t burn at all. The requirement is to introduce a highly pre-heated but variable volume of air for the different stages of combustion. This is done very efficiently by the secondary air tubes inside the Pyroclassic IV fire.
All fires consume large volumes of air in order to extract the oxygen required to burn their fuel. One kilogram of wood needs 3.7m3 of air to burn completely, although this is only a theoretical minimum for stoichiometric combustion. Such ideal combustion does not exist in real life as only some of the oxygen in that amount of air can be used and therefore 'cool fires' need some 200% - 300% excess air to get the oxygen they need. Therefore some 7 - 10m3 of air per kilogram of wood pass through the firebox cooling the core temperature inside it and cooling air below 600°C , which kills the reaction needed to burn the volatiles. In most fires the air needs of the fire make it work against itself making it inefficient and polluting, the excess air it uses only goes up the chimney with all that gas, tar and particulates. A Pyroclassic IV only uses super-heated air in its secondary burn cycle ensuring there is no cooling of the firebox and no excess air consumed.
Burning wood scientifically is done very effectively by the Pyroclassic IV freestanding woodburning fire but even the cleanest and most efficient woodburning stove needs logs which are as dry as possible to give the best output from your fuel. Check the moisture content of your wood when you buy it and then let nature do the hard work for you. Stack it off the ground in an open sided, roofed store to allow plenty of air flow around it for as long as possible or at least until the moisture content is below 20%. It’s then ready to be used in your Pyroclassic fire to give you a nice warm house right through winter in the most efficient and cleanest way possible.
Can a woodburner be exempted from complying with the National Environmental Standards for Air Quality.
No. The standards were introduced to ensure a baseline level of national consistency. Allowing exceptions to the National Environmental Standards for Air Quality would go against the intent of the standards and would compromise their integrity.
See more information at http://www.mfe.govt.nz/air/national-environmental-standards-air-quality
Can I use other tools in my Pyroclassic fire chamber?
Depending on how the fire is used, the surface of the cylinder can wear and erode over time. This can be accelerated through using the wrong tools, such as a flat shovel to remove ash (shown below). As you can see, this has resulted in two carved grooves in the ceramic. Although this is not ideal, it is not of a major concern as the cylinder wall is over 35mm thick so it will not compromise the integrity of the structure and the surface can easily be repaired through the application of veneering cement, which can be purchased from our online shop.
Why are gases and smoke entering the room when the door is opened?
The most likely reason for this is that your flue is clogged and may require sweeping.
Other possible causes:
- You could have a very cold flue temperature. Allow initial start up fire to warm flue pipes.
- Loading door opened during maximum degassing of fuel. Wait until flames disappear.
Do you recommend using Smartburn in the Pyroclassic?
We have not carried out any testing with the SmartBurn in the Pyroclassic so we have no official data to go from and based on the limited knowledge we have of it there is little to suggest that it would make any significant difference to the burn environment inside a Pyroclassic.
A Pyroclassic in good working condition should not need a SmartBurn or similar in it to achieve a good, clean, effective and efficient burn.
Why are there cracks and deterioration in my Pyroclassic cylinder?
This is a natural way to relieve built-up stress in refractories. It has no effect on operation, performance or useful life of the unit. The firebox is an arch structure, the most stable and permanent construction known. These cracks will develop over time and is nothing to worry about.
Due to it being cast as a one piece cylinder it goes through some expansion and contraction every time it is heat cycled. This is just the cylinder relieving its inert tension and results in a variety of different levels of cracking.
These cracks and blisters can slowly grow over time due to erosion through use. If you do not like the appearance of the cylinder when cracks appear, you can purchase veneering cement which can be mixed to a toothpaste like consistency and inserted into the cracked areas.
The story goes that the two original designers each had a Pyro and one touched up his cylinder every year and the other never touched his...25 years later both fires were still working albeit one was looked in better looking condition internally than the other!
25 year-old Pyroclassic II Cylinder
How does burning work with the Pyroclassic IV?
Solid wood must change to gas and vapour before any burning can take place. This change occurs by heating wood to high temperatures to make the best gas fuel, low temperatures will make smoke and tars that are simply unburnt fuel. The Pyroclassic® IV is a North/South burning fire so the fire is started in the front of the fire chamber and continues along the length of the wood to the rear. To make the best use of your firewood please ensure logs are placed lengthways into the fire chamber – NOT sideways. Your objective is to achieve a high temperature in the fire chamber quickly, which is easy using the Turboslide and dry wood. You will never get the fire to burn correctly if you try starting fires with green or wet wood. The only fuel authorised for use with this appliance within Urban Clean Air Sheds and Smoke Control Zones is well seasoned wood with a moisture content of 25% or less on wet weight basis, 12-18% is ideal.
I am building a very airtight home. Do I need to install an air vent?
All wood fires need oxygen to operate effectively. The Pyroclassic IV needs 3.6 cubic metres of air per kilogram of wood. Like all wood fires, if you starve the unit of air, which can easily happen with airtight homes, it will not operate correctly and puff smoke back into the room. For these reasons, we strongly recommend you put in an air vent, approximately the size of a brick.
What are the clearances for a Pyroclassic IV installed on a mini raised woodbin?
You can download the installation clearances for installing a Pyroclassic IV on a mini raised woodbin HERE.