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THE FIREPLACE DOCTOR


Modern solid fuel heaters are generally of excellent quality - problems are usually due to some difficulty with the installation, chimney or fuels.

Most problems centre around:
  • FUEL - Is Wood Fuel absolutely dry? Have you got the right Solid Fuels
  • CHIMNEY - Does The Chimney Effect work? Is the chimney high, hot, smooth and sealed?
  • Is the fire INSTALLED right? Check the Building Rules in your area.


  • COMMON PROBLEMS

    SMOKE FROM THE CHIMNEY Some Solid Fuels, such as peat or Wood Fuel which is any way damp, and bituminous coal in any form will emit significant Smoke unless burned on specially-designed appliances. Remember too that 'smokeless' fuels smoke less, they are not smoke free. It is quite normal for a little smoke to be emitted from the chimney when the fire is cold, but good quality, well-made appliances should emit little or no smoke when burning clean very dry wood or smokeless mineral fuels such as natural anthracite. There is advice on correct technique for burning wood under Wood Fuel.

    DAMAGED LINERS Stoves get very, very hot inside, it is quite usual for ceramic or vermiculite firebox liners to crack or craze, often within a very short time. They need usually only be replaced when they have almost completely disintegrated. Help them last longer by using only very dry fuel.

    DETERIORATION OF SURFACE FINISH: The siloxane paint usually used on stoves can withstand very high temperatures, but it is easily scratched and soon becomes dull, it is to be expected that it may need touching-up fairly regularly using a proper stove refurbishment paint. The vitreous enamel finish used for bright, shiny colours on many stoves is almost impossible to scratch, but it can chip. Vitreous enamel cannot be repainted or repaired.

    POOR HEAT OUTPUT: A stove can heat a typical room of about 12m³ volume for each kW of output, so a 5kW model can heat up to (12 x 5) 63m³, a room of about 5m square. The actual size depends on the insulation and air-change ratio of the room. To attempt to heat a larger room will result in excessive fuel consumption and damaging overheating. For more precise calculations see Heat Need. Other causes of poor output are unsuitable fuels (commonly less than perfectly dry wood) or inadequate chimney draught, see The Chimney Effect.

    LACK OF CONTROLLABILITY Wood and some other fuels may burn excessively until the gases in them have been used up. You can reduce this effect by making sure that the fire is set to 'low' for a while before refueling and checking that the door seals fully. Some appliances are deliberately made incapable of being fully closed down, in order to prevent smouldering and smoke emissions. On such appliances adjust the heat output by how much fuel you put on, as well as by using the controls.

    DIFFICULTY BURNING FOR EXTENDED PERIODS If the fire goes out with fuel still in the firebox, then this is probably because too little air has been reaching it, try leaving the air controls open a little more. Check that the door seals are sound and that there are no cracks or gaps anywhere in the flue. The fuel must be absolutely dry. Longest burning is likely to be achieved with harder fuels, such as anthracite, on appliances capable of burning this.

    CONDENSATION onto cool surfaces inside the stove can be severe if fuel is in any way damp. With damp Wood Fuel this can be very severe. Appliances with boilers should be fitted with means to guard against the condensation which causes corrosion cold water enters a hot boiler, for instance by having a thermostat which prevents pumped circulation if the water temperature is low. Use only very dry fuel.

    OVER-FIRING: It is possible to leave the fire too long with the controls set too high leading to 'over firing', seen as glowing metal parts, excessive chimney temperature and risk of parts failing or chimney fires. Always set controls to the lowest practical setting. A chimney thermometer, from your local stove shop, can help.

    SMOKE COMING INTO ROOM Fumes contain Carbon Monoxide - smoke emission must NEVER be tolerated, causes might be:
    NEW STOVE: There is often a smell and sometimes visible fumes as the paint cures. This normally stops after an hour or so.
    INADEQUATE SEALS: Are all flue pipes and connectors absolutely gas-tight? Is the inside of the chimney absolutely air-tight from top to bottom. Even the tiniest crack or gap can spoil the draught. Does an inset appliances fully seal against the fireplace?
    BLOCKED THROAT PLATE: Has soot and ash collected inside the flueways, on the 'throat plate' or 'baffle plate' beyond the firebox?
    UNSUITABLE, BLOCKED OR UN-SWEPT CHIMNEY: The first requirement for correct operation is a sound chimney. In any case of doubt engage a professional sweep or chimney engineer.
    COLD CHIMNEY: Is the chimney fully insulated throughout its entire length to encourage The Chimney Effect? It may sometimes be acceptable to have a very short (say up to 1m) length of uninsulated pipe to connect an appliance to the insulated chimney, but more than this is likely to cool flue gases to the point where they no longer rise, leading to difficulty lighting, smoke emission, condensation and build-up of tarry deposits. Tall masonry chimneys, even if soundly constructed, can take many hours of use to dry out and warm up enough.
    POOR AIR SUPPLY: As The Chimney Effect shows, no appliance will burn at all without a supply of air from outside. It is commonly accepted that a closed solid fuel appliance ought to have about 550mm² of free air entry area for every 1kW of nominal heat output, of which the first 5kW or so can often be supplied though the cracks around door, windows etc in older properties. There are different rules for Open Fires.
    Lack of air to the fire is a common cause of smoking and poor performance. Air supply problems may be worse in certain wind conditions (often incorrectly ascribed to 'downdraught', which is in fact very rare), where air can be sucked out of the room. The answer is to fit an air vent, as near to the fire as possible, facing into the usual wind direction.

    DOWNDRAUGHT: Wind can blow down a chimney if there is something higher nearby such as a tree, hill or high building. Fitting an anti-downdraught cowl to the chimney top can cure this. Types which cannot be swept through are not recommended. Downdraught is actually fairly rare, smoke emission problems commonly have other causes.

    CHIMNEY FIRE: In the rare event of deposits inside the chimney igniting (roaring sound + dense smoke and sparks from the chimney) immediately close the door, shut all air controls and call the fire brigade. Prevent fires by using very dry fuel and having your chimney swept regularly.

    WON'T BURN AT ALL. Have you got the right fuel? Hard fuels such as anthracite will simply not burn on ordinary open fires or on many types of closed stoves. Mineral fuels will not burn at all in flat-bed wood burning stoves with no grate or low-level air supply, such appliances burn wood very effectively, but they will even extinguish burning coal. Damp or 'green' Wood Fuel can be almost impossible to ignite.

    FUNNY SMELLS. Humans have evolved an extraordinary ability to detect wood smoke in very tiny concentrations. It is fabulously unlikely that you will be able to operate a wood burning appliance inside a building without some slight smell of wood smoke, but the presence of such a smell does not of itself indicate danger - see Carbon Monoxide.

    ODD NOISES: Stoves and chimneys sometimes make a slight whistling noise as air is pulled though them, or a creaking noise as metal parts expand and contract. These noises usually reduce over time.

    EXCESS ASH PRODUCTION: Peat, lignite and certain manufactured Solid Fuels do produce high levels of ash, consider trying a different fuel. Wood Fuel, however, produces almost no ash - the white powder which falls from it is cellulose from the cell walls and will burn if kept hot enough, so don't de-ash a wood fire until absolutely necessary. Instead, allow a bed of cinders and ash to build up.

    DIRTY WINDOW: Wood logs can be very smoky, especially if not entirely dry, raw bituminous coal is very dirty indeed and many 'smokeless' fuels produce plenty enough smoke to severely stain stove windows.
    When using smoky fuels always have the stove's 'over-fire' or 'airwash' control (usually a slider above the fire-door) at least slightly open to pull extra air in above the fire, pushing dirty gases away from the window and helping them to ignite. If the appliance does not have such a control you can achieve the same effect by not quite shutting the fuelling door for no more than two or three minutes when you first light, or refuel, the stove.
    Window stains can be removed by either operating the stove at a high rate for a few minutes to burn the dirt off, or using an ordinary supermarket spray bleach cleaner when the fire is cold.
    The ceramic 'glass' commonly used for stove windows will develop very tiny cracks on its surface after a period of use, this is normal.

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    | © Soliftec Ltd | SiteMap This page updated 02/09/2014


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