FAQs

Please click on the questions listed below to reveal the answers:

Stoves:

Building Regs

Please click here for full details on the building regs that apply to wood burning stoves.

Can I run my stove with the doors open?

In most cases the answer is yes, but the success of this depends on the capability of the chimney to clear the smoke and fumes associated with wood and solid fuel. Sparks and ash can fall from the stove so spark guards are a good idea and can be purchased with most brands of stoves. It should be remembered that the efficiency of the stove will suffer when run with the doors open. 

Cast Iron or Steel – Which to choose?

Generally stoves fall into 3 price levels with steel often being the cheapest, cast iron next and enameled cast iron the most expensive. The most obvious difference is the appearance as cast iron can be moulded into intricate shapes and detail. Steel stoves are plainer, only the doors are cast iron and therefore the only decorative part of the stove. Both types are generally equally durable and efficient. 

Do I need any special ventilation?

All live fires need ventilation to ensure safe and complete combustion although stoves require significantly less than open fires.  Stoves rated up to 5KW require sufficient room ventilation only.  Stoves rated in excess of 5KW do require permanent ventilation and your installer will need to refer to the installation instructions for the specific size required.

Lighting and combustion?

The primary air is drawn into the stove through the slide on the door.  The secondary air is regulated with the aid of a slider above the door.  The heated secondary air flows down the viewing window and then feeds the fire; it is this secondary combustion that completes the burning cycle by turning unburned volatiles into flame.

 As much as half of the heat obtainable from wood is obtained from this secondary combustion.  It is important that the firebox temperature is maintained at a high level as this also aids complete combustion.  The use of a stove pipe thermometer is recommended, as this will indicate stove performance.  For Example, when first lighting a stove it is important to get it really hot before closing the burning rate down.  The firebox temperature should reach 400C which equates to approximately 250C at the flue pipe.

If the stove is operated at this optimum level very clean combustion can be achieved with little or no smoke visible from the chimney.  

What Stove size (KW output) do I need for my home?

Many stoves are chosen on their physical size to match an existing hearth or opening but this has little relationship to the heat requirement of the room.  Notwithstanding variations in heat loss in individual properties, as a general rule you will need 1KW of heat for every cubic metre.  This is based on a room temperature of 21 degrees Celsius at an ambient of -1 degree Celsius.  For example, an average living room measuring 2.3m x 4.9m x 4.7m divided by 14 would require a stove with a nominal output of 4KW.

Where can I install a stove?

 A suitable site will have a non-combustible hearth and offer direct access to the flue system.  The position will need to be at predetermined clearances from both combustible and non-combustible surfaces.  These are included in both the stove installation instructions and the building regulations 2002 approved document J.

Will my new stove include fitting instructions ?

Yes all new stoves include detailed instructions covering installation, operation, general care and maintenance.

Will a stove be more efficient than an open fire?

Yes a stove will operate at efficiency levels between 65-85%.  Most open fires operate at levels of 25% or less.

Chimneys:

Chimney Liner Installation
Do I need to line my Chimney?

If the chimney leaks it must be lined. However, a chimney liner concentrates the heat and gives a positive updraught which will make your stove more efficient and easy to control. 

Do I need a Cowl?

It is not compulsory but is often a good idea for the following reasons: – Cowls with mesh can stop birds nesting in the chimney. Specially designed cowls prevent back draughts and cowls with metal tops prevent rainwater from falling down the chimney. Some cowls combine all 3 functions.

Flue/chimney requirements?

Solid fuel and wood burning stoves require a class 1 flue system.  Minimum overall height must be 4.5m to provide sufficient draught to safely exhaust the products of combustion.  The flue/chimney system may be either mineral or stainless steel and must conform to current building regulations.  There are separate regulations covering the installation of stoves in park homes and boats.

Existing chimneys should be clean, sound and inspected by an expert before installation and lined, if necessary, with a class 1 chimney liner.  Anslow Woodburners are happy to advise you further.

How often do I need to sweep my chimney?

This should be done at least annually and preferable by a national association of chimney sweeps registered member who will provide you with a certificate of visual condition covering the flue/chimney and compliance with ventilation requirements.

What is a soot fall?

The build-up of deposits in the chimney can lead to a soot fall which can block the chimney. If the chimney is blocked smoke will very likely leak into the house in great quantities. This is dangerous especially if this happens when you are asleep.

Soot builds up in a chimney over time, especially when burning wood or bituminous coal and especially when slow burning overnight. From time to time the soot becomes dislodged or grows to such a size that it falls down. A soot fall is accumulative meaning that it ‘snowballs’: if the soot fall starts at the top of the chimney then it can bring down much of the soot below it as well. This can block the chimney or stove flue pipe. The stove can then smoke a lot on a far grander scale than the wisps of smoke alerting the user to the fact that the flue or chimney needs sweeping. 

Fuel:

Which fuel to choose?

Wood

Wood is a renewable source of fuel, provides the best flame effect and a wonderful smell there will be less ash than with the equivalent coal or smokeless fuel fire. Well-seasoned wood can be difficult to obtain and is bulky to store.

Smokeless fuel (Multifuel)

Smokeless fuels such as anthracite produce more heat than wood and burn more slowly, enabling fires to slumber throughout the night. Smokeless fuel can be burnt in smoke control zones. Smokeless fuel makes more ash than wood, is more expensive to buy and can be dirty. 

Biomass:

Biomass Boiler Maintenance

Biomass boilers like other boilers should be serviced regularly by a qualified service engineer.

The biggest difference with biomass boilers is the requirement to dispose of ash that builds up as part of the combustion process.  Wood combustion produces 0.5-1.5% by weight of ash, depending on fuel quality. This ash collects in an ash pan under the grate. It has to be removed manually at periodic intervals depending on the heating demand. Automatic de-ash systems put the ash into an ash bin, reducing the amount of work required. However, the ash bin still requires emptying periodically.  The ash can then be used as a wood fertilizer

Terminology:

What is a Gasification boiler?

Full details can be seen here.

What is airwash?

Tar and other deposits will condense onto any cold surface inside a stove, especially when burning wood. This can leave a black/brown deposit on the window of the stove that blocks the view of the fire. 

A stove with an airwash system has air vents that direct a flow of air down across the glass which helps to stop tar being deposited on the glass.
Burning your stove relatively fast can also help to cut down on deposits as the firebox temperature stays high which means that much less tar is deposited. This can even burn off tar deposited earlier. 

What is cleanburn?

When wood burns most of the visible flames are in fact due to gases released by the hot wood. Inside the firebox of a stove the oxygen can quickly become used up and in the absence of oxygen some of these gases remain unburnt and exit up the chimney.

A cleanburning stove generally introduces another supply of air into the firebox, preheated so as to maintain the firebox temperature. This supply of air is often introduced to the firebox through a series of holes which results in jets of air entering the firebox – this means that the air and gases mix well and encourages more complete combustion.
Once a wood stove is running nice and hot you may see jets of burning gas hanging in the firebox where the supply of air enters. 

What is a baffle?

A baffle plate is a plate usually made of metal that sits inside the stove over the firebox. This plate blocks off the direct exit to the chimney which means that the hot flue gases have to travel further before they get out of the stove. This means that there is more time for the flue gases to be mixed with air and fully combust in the firebox and that more heat can be transferred from the firebox to the stove and/or water in the boiler.

So a flue baffle makes the stove more efficient and can increase it’s heat output.

What are firebricks?

Firebricks are found in the firebox of a stove and protect the insides of the stove from the intense heat of the fire. Modern firebricks are often made from vermiculite a light highly insulating material that not only protects the inside of the stove but also increases the temperature in the firebox thus increasing efficiency.

Many boiler stoves have a wraparound boiler which forms the back and sides of the firebox so firebricks are often unnecessary in these boiler stoves.
In boiler stoves with clip in boilers the boiler replaces the firebricks at the back of the stove and the firebricks at the sides remain in place.

What is RHI?

RHI is the Renewable Heat Incentive –  a UK Government scheme set up to encourage uptake of renewable heat technologies among householders, communities and businesses through the provision of financial incentives. For full details including savings please take a look at our RHI page.

What is meant by Efficiency?

Most people regard efficiency as the maximum heat output of a stove or fire. The efficiency referred to in manufacturers literature is the difference between heat to the room and heat lost up the chimney. In simple terms, an 80% efficient stove will give £8 worth of heat for every £10 spent.