Knowledge Base

Most stoves produced both today and historically tend to be radiant stoves. Radiant stoves (as the name suggests) radiate heat from the body of the stove and through the glass. This results in a reasonably concentrated area of heat around and directly in front of the stove.

Convector or convection stoves consist of a central combustion chamber or firebox (like a radiant stove) but normally have additional side and top panels. They are designed in such a way that transfer of heat from the firebox to the air within these channels results in hot air being circulated into the room.

Convection stoves are better suited to oddly shaped or longer rooms where the room would benefit from a greater movement of air.

Many manufacturers producing boiler stoves struggled to meet the requirements of the Eco Design 2022 emissions test and so decided to cease production of many of their models.

However, in 2022, due to a resurgence in interest in boiler stoves and other alternatives to gas heating, several manufacturers have re-invested in their boiler stove model offering and have been able to redesign them to meet the requirements of Eco Design.

Cast iron has better heat retention and conductance properties. It will not warp as easily as steel, and more intricate stove designs can be achieved using the casting process such as ribbed sides, emblems etc. All of the cast iron stoves we sell are of an excellent quality; cheaper stoves should be avoided for a number of reasons including: inferior quality of castings, poorer build quality and general finish. As the old adage goes: you pay for what you get!

Steel stoves are generally cheaper to buy than cast iron stoves. Steel stoves will heat up quicker than cast iron but will also cool down quicker as steel does not retain heat as well as cast iron. Steel expands and contracts more quickly than cast iron therefore can be susceptible to ‘hot spots’:- where certain areas of the stove are subject to greater temperatures than other areas of the stove. Steel stoves generally have cleaner lines than cast iron as intricate mouldings cannot be achieved, however most traditional looking steel stoves do have cast iron doors.

To calculate the size of stove you need, you should measure the height, width and depth of the room its going to heat and then plug the results into our handy Stove Output Calculator

In Metres: (room height * room width * room depth)/14

Or in Feet: (room height * room width * room depth)/494

A multi-fuel stove can burn wood as well as solid fuels such as coal, however you cannot burn coal on a dedicated wood burning stove. Wood burns best on a bed of ash and burns from the top downwards, because of this dedicated wood burning stoves do not require (although some have) a grate or firebars which allow for air to reach the fuel from the underside. Grates can be of the fixed or riddling variety, fixed (as the name suggests) are immovable. Riddling (movable) grates or firebars allow for the fuel to be ‘riddled’ which is the term used for the removal of ash from the combustion chamber, this also serves to ‘stoke’ the fire.
Most stoves with a riddling facility allow this happen without having to open the stove doors. Coal burns best with combustion air fed from both the bottom and the top of the fuel, for this reason coal burning stoves or multi fuel stoves are equipped with grates or firebars.
Another feature of a multi fuel stove is an ashpan. The ashpan is the metal pan that sits in the bottom of the stove collecting the ash that falls through the grate, by riddling the stove you cause ash to fall through the firebars/grate into the ashpan. This allows for relatively clean removal of ash from the stove. It is important that you do not allow large amounts of ash to collect in the pan before emptying; ash has pretty good insulating (reflective) properties and doing this can cause extremely high temperatures directly under the grate which can lead to warped, cracked or even completely burnt out fire grates and bars.
Generally multifuel stoves cost between 5-15% more than there wood burning equivalents (where a manufacturer offers both options for a model of stove) but the extra cost is usually worth it as it gives the owner the flexibility of choice of different fuels and the practicalityof an ashpan for easy cleaning. If you live in a smoke control area choosing a multifuel stove (that can burn approved smokeless fuels) as opposed to a DEFRA approved wood burner means that the range of stoves that you can look at is not reduced.

The Future Has Arrived. The stoves of tomorrow are available today.

SIA Ecodesign Ready stoves are designed to reduce PM emissions by burning wood more efficiently and completely.

The stoves have been independently tested by an approved test laboratory and met the emissions and minimum efficiency criteria for Ecodesign. The test results have also been verified by HETAS and listed on our web site. Click on the Ecodesign logo to see verified list of SIA Ecodesign Ready stoves

Ecodesign is the European-wide programme to lower emissions. It is due to come into force for stoves in the UK in 2022. SIA Ecodesign Ready stoves will meet the Ecodesign requirements and are available now. The PM emissions limit for Ecodesign is 55% lower than for DEFRA exempt stoves.

Burning wood produces particulate matter (PM) but the amount produced depends on how the wood is burnt. Independent research conducted by Kiwa Gastec on behalf of the SIA has shown that SIA Ecodesign Ready stoves can reduce particulate emissions by 90% compared to an open fire and 80% compared to an old stove (see the test results at the bottom of the page).

 

Both Defra and the Mayor of London are backing the installation of SIA Ecodesign Ready stoves to reduce emissions from wood burning.

In its Clean Air Strategy Defra recognises that all wood burning is not the same and that reductions in particulate emissions, (PM), can be achieved through the installation of Ecodesign Ready stoves burning Ready to Burn logs.

The Mayor of London showed his support for Ecodesign Ready stoves by sponsoring two adverts in the Evening Standard encouraging Londoners to only burn dry wood and choose a Defra exempt stove which is also Ecodesign Ready.

 

Stoves today are available for use with gas, oil, electric, wood, house coal, solid smokeless fuels and many are even capable of burning more than one type of fuel.

Wood is the most commonly used fuel on open fires or stoves and rightly so. Burning wood does release carbon dioxide into the atmosphere, however the amount of carbon dioxide released is approximately the same as the amount absorbed by the tree during growth. Therefore wood is widely accepted as a carbon neutral fuel. Wood fuel is available in many forms: Logs, Pellets, woodchips, heat logs and wood briquettes. With conventional energy prices increasing wood has become an even more attractive fuel for heating.

Wood can be divided into two major classes, hardwood and softwood. Measured by weight, hardwoods and softwoods have similar energy contents (around 20MJ/kg dry) however Hardwoods are typically twice as dense as softwoods as they are slower growing, so you would require less hardwood to produce the same heat output as softwood.

The most important factor when using wood as a fuel is that it has a low moisture content (MC). Freshly harvested wood can contain as much as 80% depending on the species and the time of year it was felled. As the wood moisture level increases, its useful energy content decreases. At 60% MC wood can have an energy content of 6MJ/kg but at 25% MC this can increase to 14MJ/kG. Burning wet wood produces excess steam and excess smoke which is a sign of incomplete combustion, this increases the build up of tars in the chimney which enhances the risk of chimney fires and reduces the efficiency of the chimney. To obtain maximum efficiency from your stove using the minimum amount of fuel only burn wood with a moisture content of 20% or less. The use os a moisture meter is the best way to monitor this. (quick find no.SMO2535).

Removing the water from the wood is known as seasoning. This term suggests a period of time, and for natural air drying up to two to three years is recommended. We offer a selection of log stores for this purpose, please contact us for details.

Firebox Stoves does NOT recomend the use of pallet's or any treated / painted wood. The use of wood composites for example Plywood, chipboard, MDF etc. should be avoided & could prove VERY DANGEROUS.

Good Wood Guide;

A Quick Reference Guide to Explain What Woods Are Good to Burn and Their Qualities.

Alder: Poor heat output and short lasting. A low quality firewood. Produces a charcoal that burns steady.

Apple: Great fuel that burns slow and steady when dry, with little flame, sparking or spitting. It has a nice scent. Great for cooking.

Ash: Considered one of the best burning woods with a steady flame and good heat output. Easy to saw and split.

Beech: Similar to ash, but only burns fair when mildly wet. It may shoot embers out a long way. Is easy to chop.

Birch: This has good heat output but burns quickly. The smell is also pleasant. It will burn unseasoned. Can cause gum deposits in chimney if used a lot. Rolled up pitch from bark makes a good firestarter and can be peeled from trees without damaging them.

Blackthorn: Burns slowly, with lots of heat and little smoke.

Cedar: This is a great wood that puts out a lot of lasting of heat. It produces a small flame, a nice scent, and lots of crackle and pop. Great splitting wood. Good for cooking.

Cherry: A slow burning wood with good heat output. Has a nice scent. Must be seasoned well. Slow to start.

Chestnut: A mediocre fuel that produces a small flame and weak heat output. It also shoots out ambers.

Douglas Fir: A poor fuel that produces little flame or heat.

Elder: A mediocre fuel that burns quickly without much heat output. Tends to give off a thick (Apparently poisonous!!!) smoke. Probably best avoided.

Elm: A variable fuel, can be subject to dutch elms disease. (http://en.wikipedia.org/wiki/Dutch_elm_disease) Usually has high water content. May smoke violently and should be dried for two years for best results. You may need faster burning wood to get elm going. A large log set on the fire before bed will burn through the night. Splitting can be difficult and should be done early on.

Eucalyptus: A fast burning wood with a pleasant smell and no spitting. It is full of sap and oils when fresh and can start a chimney fire if burned unseasoned. The stringy wood fibre may be hard to split and one option is to slice it into rings and allow to season and self split. The gum from the tree produces a fresh medicinal smell. Not be the best for cooking with.

Hawthorn: Good firewood. Burns hot and slow. Traditionally gathered as bundles or 'faggots' (yeh really...) for burning in winter.

Hazel: An excellent fast burning fuel but tends to burn up a bit faster than most other hard woods. Allow to season.

Holly: A good firewood that will burn when green, but best if dried a year. It is fast burning with a bright flame but little heat.

Hornbeam: Burns almost as good as beech with a hot slow burning fire.

Horse Chestnut: A low quality firewood with a good flame and heating power but spits a lot.

Laburnum: Completely poisonous tree with acrid smoke that taints food and is best never used.

Larch: Crackly, scented, and fairly good for heat. It needs to be seasoned well and forms oily soot in chimneys.

Laurel: Produces a brilliant flame.

Lilac: Thinner branches make good kindling, whilst the thicker burn well with a clear flame and a very pleasant smell

Lime: A poor quality fuel with dull flame. Good for carving but a massive waste to burn it.

Maple: A good all round firewood.

Oak: Oak has a sparse flame and the smoke is acrid if not seasoned for two years after WINTER FELLING. Summer felled Oak takes YEARS to season well. Dry old oak is excellent for heat, burning slowly and steadily until whole log collapses into cigar-like ash.

Pear: Burns with good heat, good scent and no spitting. Needs to be seasoned well.

Pine: (Most Species) Burns with a splendid flame, but is prone to spitting. Needs to be seasoned well but can leave an oily soot in the chimney. Smells great.

Plane: Burns pleasantly, but is prone to throwing sparks if very dry.

Plum: Provides good heat with a nice aromatic sent.

Poplar: A terrible fuel that doesn't burn well and produces a black choking smoke even when seasoned. A DEFFINATE NO GO!

Rowan: A good firewood that burns hot and slow.

Rhododendron: Old thick and tough stems burn well.

Robinia (Acacia): Burns slowly, with good heat, but with acrid smoke. Not a problem in a stove!

Spruce: A poor firewood that burns too quickly and with too many sparks.

Sycamore: Burns with a good flame, moderate heat. Useless green.

Sweet Chestnut: Burns when seasoned but tends to spits continuously and excessively.

Thorn: One of the best firewood’s. Burns slowly, with great heat and little smoke.

Walnut: Low to good value to burning. Leaves a nice aromatic scent.

Wellingtonia (Giant Sequoia): Poor for use as a firewood.

Willow: A poor fire wood that must be dry to use. Even when seasoned, it burns slowly, with little flame. Prone to spitting.

Yew: This burns slowly, with fierce heat. Gives off a strong pleasant aroma.

Smokeless fuels, as the name suggests burn with little or no visible smoke compared with house coal, they are suitable for use in Smoke Control Areas. The calorific value (the amount of heat released during combustion for a specified amount) varies with the different types of smokeless fuels but is typically between 8-9.5kW/kg.

Smokeless fuels can be divided into two categories: natural solid fuels and manufactured solid fuels.

Manufactured solid fuels are available in two forms: coke and briquettes.

Coke is produced using bituminous coal which is heated in a process called ‘carbonisation’. This drives off the volatile matter and smoke producing impurities contained within the coal and depending on the temperature level will either produce ‘hard coke’ or ‘soft coke’. Hard coke is a dense grey fuel containing very little volatile matter and is suitable for use on closed appliances only. Soft coke is black and has an airy, sparse structure. It is suitable for use on open fires and closed appliances.

Briquettes can be made using various methods including heating bituminous coal to its softening point in a fluidised bed pressing the particles together whilst at the same time driving off volatiles. Another process grinds it, finely binding it together with a binder. These are suitable for use on open fires or in room heaters and boilers.

Beware of petroleum based fuels such as petroleum coke as they can seriously damage appliances and flues due to their high heat content and low ash content, if in doubt consult your coal merchant and/or appliance manufacturer.

Natural smokeless fuels or Anthracites are available in different sizes, Large nuts (Stove nuts), Small nuts (Stovesse). Depending on size, Anthracite can be used in room heaters, independent boilers and cookers and nowadays grains and beans are available which are suitable for gravity fed boilers. Anthracites are authorised for use in Smoke Control Areas

House coal or bituminous coal is the most traditional fuel for open fires. It is a naturally occurring mineral and is not subject to any processing. It is ideally suited to open fire as it burns freely and does not require poking. It has a gross calorific value (the amount of heat released during combustion for a specified amount) of about 7.5kW/kg. Bituminous coal is not suitable for use in Smoke Control Areas; however there are certain exempt appliances that are able to burn certain specially sized Bituminous coals within Smoke Control Areas.

Approved Document J or Part J is the document within the Building Regulations that cover England and Wales that deals with ‘combustion appliances and fuel storage systems’. This document has six requirements, but only the first four (J1, J2, J3 and, yes you guessed it J4) apply to the installation of solid fuel appliances. The description of these four requirements is as follows:

J1 Air supply J2 Discharge of products of combustion J3 Protection of building J4 Provision of information

The purpose of this document is to provide practical guidance to obtaining compliance with the Building Regulations for some of the more common situations encountered during the installation of an appliance, however the document states that ‘there is no obligation to adopt any particular solution contained in an Approved Document if you prefer to meet the relevant requirement in some other way’.

The Building Regulations for Scotland and Northern Ireland differ slightly to those for England and Wales and precise details should be checked for compliance..

HETAS are the organisation recognised by the government to approve solid fuel domestic heating appliances, fuels and associated equipment and services, HETAS independently confirm by means of testing manufacturers claims of appliance performance, heat output and efficiency.

HETAS in conjunction with the Solid Fuel Association has introduced a competent person’s registration scheme. The objective of this scheme is to ensure that any consumer wishing to have a new appliance installed or an existing appliance serviced can contact a competent engineer or company employing competent engineers.

Customers using a HETAS registered engineer will be issued a HETAS certificate of compliance on the completion of installation work. The information on the form is used to record your installation and in England & Wales it is used to notify your Local Authority Building Control Department of the work that was undertaken. This ‘self certification’ by registered installers takes the place of a Local Authority Building Notice which could otherwise cost the customer a significant amount of money. The HETAS installer is charged a small fee by HETAS for this service but much less than the charges incurred if you seek a Building Notice via the Local Authority. Failure to notify the Local Authority can be an offence resulting in action being taken against installers or Householders. The information will be available to Solicitors in any home selling process and will be used when calculating the overall home energy efficiency within the Home Information Pack (HIP).

In England & Wales Regulation 16A of the Building Regulations 2000 was amended in 2004 and places a duty on HETAS registered installers to give the property owner a certificate stating that the work carried out by the installer complies with regulations 4 and 7 of the Building Regulations.

The Clean Air Acts of 1956 and 1968 were introduced to deal with the smog’s of the 1950s and 1960s which were caused by the widespread burning of coal for domestic heating and by industry. Under the Clean Air Act local authorities may declare the whole or part of the district of the authority to be a Smoke Control Area. It is an offence to emit smoke from a chimney of a building, from a furnace or from any fixed boiler if located in a designated Smoke Control Area. It is also an offence to acquire an ‘unauthorised fuel’ for use within a Smoke Control Area unless it is used in an ‘exempt’ appliance. The current maximum level of fine is £1,000 for each offence.

If you live in a Smoke Control Area and wish to use a wood or multi-fuel appliance, fear not, as there are many exempt appliances on which you can burn authorised fuels. Authorised fuels are fuels which are authorised by Statutory Instruments (Regulations) made under the Clean Air Act 1993 or Clean Air (Northern Ireland) Order 1981. These include inherently smokeless fuels such as gas, electricity and anthracite together with specified brands of manufactured solid smokeless fuels. These fuels have passed tests to confirm that they are capable of burning in an open fireplace without producing smoke. Exempt appliances are appliances (ovens, wood burners and stoves) which have been exempted by Statutory Instruments (Orders) under the Clean Air Act 1993 or Clean Air (Northern Ireland) Order 1981. These have passed tests to confirm that they are capable of burning an unauthorised or inherently smoky solid fuel without emitting smoke.

Check if you are in a Smoke Control Area at the following website: www.uksmokecontrolareas.co.uk

If the output of your stove is greater than 5kW then you do need permanent ventilation to the room. There is no stipulation in the building regulations as to the type of vent that must be used however examples would be air bricks, core drill vents etc. We stock a range of HETAS approved air vents in the

For stoves with outputs over 5kW the free area requirement of the vent is 550mm² per kW over and above 5kW. So an 8kW appliance would have a free air requirement of 1650mm². The amount of ventilation required does vary for other types of appliance such as open fires or stoves with flue draught stabilisers, please contact us or your HETAS approved installer for advice.

A sufficient air supply for a solid fuel fired appliance is very important. It ensures that complete combustion of the fuel occurs and also allows the chimney to function correctly. An insufficient air supply can have serious consequences. Smoking will occur and also increased levels of carbon monoxide will be produced which can be life threatening.

If you experience a seeming lack of heat from your stove, it is possible that your flue system is producing too much updraught and is effectively sucking the heat up the chimney. One way to identify this is to attach a flue thermometer (Product code GC1000) to the flue pipe approximately 200mm from the top of the stove for best results

If your thermometer displays temperatures of above 880ºC. This would indicate that you have too much draught in your chimney or your chimney may be blocked.

By fitting a flue damper you can restrict the flow of exhaust gasses from the stove, resulting in more heat entering the room. Many manufacturers now offer flue dampers as accessories for their stoves, which you can purchase with a stove, however we stock a range of generic aftermarket dampers suitable for fitting to most single walled pipes. If you have a twin walled insulated system coming off your stove please contact us for advice on a suitable solution.

Tars and carbons given off when burning wood can build up on the door glass of the appliance resulting in the reduction of the visible flame.

Many stoves offered on sale today have an airwash facility to help keep the door glass clean and allow a continued good picture of the flame (after all, this is one of the reasons why people buy stoves!).

This system allows air to enter the stove directly above the glass and pass over the surface of the glass creating a barrier of air between the glass and the flames; this prevents the tars from building up on the surface of the glass. Certain stoves now have a hot airwash system which, according to stove manufacturers, is more effective than conventional cold airwash systems.

Many airwash systems do require a certain amount of air to be drawn into the stove for the airwash system to function properly. As a low air intake volume reduces the heat output of the stove maintaining a clean glass whilst using the stove at low outputs is a difficult balance to strike. The cost of replacement stove glass is relatively inexpensive so if a thorough cleaning using a stove glass cleaner does not give good results, it may be worth considering replacing the glass.

Cracked fire bricks are a common issue, however you should only attempt to replace them if they have deteriorated to the extreme i.e. if they have badly or completely crumbled. Common causes of cracked fire bricks are over sized logs, over loading the stove, over-firing the stove or transit damage, but do not fret if they have cracked after the 1st or 2nd firing! As long as in the main they are intact they will be serving the purpose that they were designed for – maximising and concentrating the firebox temperature.

Common cause of burnt out or distorted grates and bars are as follows:

• Over-firing - this is often identifiable by an upward distortion of grate or bars

• Incorrect choice of fuel - this results in the distortion of grate or bars

• Large build ups of ash in the ashpan can result in extreme temperatures directly beneath the grate or bars often evident by downward distortion

Most stoves come with guarantees on the body of the stove however oxidation can be a common factor in the failure of such an item. If condensation is present in the flue (often due to inadequate flue gas temperatures caused by a variety of flueing problems) this can seep into the body, internal panels and around the flue collar of the stove and form rust in these areas. As the stove expands and contracts though the heating and cooling process it is possible for this corrosion to expand between the joints placing increased pressure on adjoining panels which can eventually lead to cracked panels!

This can happen on stoves in locations such as holiday cottages as these are likely to be used infrequently. If you have a stove in your holiday cottage be sure to leave the door slightly ajar during those long periods where the stove is unused, this will help prevent the build up of condensation

One reason why it is sensible to have your chimney swept frequently is to prevent the soot build up within the stove. Some stoves are designed in such a way that soot or debris that comes down the chimney can gather on top of the flue baffle or back plate. This results in a build up of temperature of this baffle as it cannot dissipate the heat as quickly through the layer of soot. As a result this can lead to this baffle burning through. If your chimney is swept regularly often the baffle plate will need to be removed to do this (unless there is another access point to the flue). Any soot that has gathered on the plate would be removed in this process, however it is good practice to remove, clean off and replace this baffle at regular intervals to avoid this unnecessary cost.

One reason why it is sensible to have your chimney swept frequently is to prevent the soot build up within the stove. Some stoves are designed in such a way that soot or debris that comes down the chimney can gather on top of the flue baffle or back plate. This results in a build up of temperature of this baffle as it cannot dissipate the heat as quickly through the layer of soot. As a result this can lead to this baffle burning through. If your chimney is swept regularly often the baffle plate will need to be removed to do this (unless there is another access point to the flue). Any soot that has gathered on the plate would be removed in this process, however it is good practice to remove, clean off and replace this baffle at regular intervals to avoid this unnecessary cost.