The HomeFire Shop Guide To Owning and Using A Wood Burning Stove.

How to reduce heating bills by up to 90%.

Making a fire for warmth is probably man's first technological invention and burning wood is the oldest method we have of heating our homes.

After thousands of years of fire making,  we've found the safest, cleanest and most efficient way to heat our homes, by burning wood, is to use a wood-burning stove.

Take 10 minutes or so to read through this guide and we will show you how to:-

• Select the right wood-burning stove for your needs.
• Get it installed safely so you don't get smoke or fire issues. #chimneyfire 
• Source and prepare the right wood for best results
• Use your stove so efficiently you can reduce your heating bills by up to 90%

According to the Stove Industry Alliance (SIA), a Wood Burning Stove is:

• 77% cheaper per kilowatt-hour (kWh) to run than an electric fire.
• 29% cheaper than a gas fire.
• Up to 50% cheaper than an LPG (Calor Gas) fire.

That is if you are buying wood to fuel your stove.

By sourcing and seasoning your own wood you can reduce your home heating bill by up to 90% compared to gas or electric powered heating.

Wood used correctly is a virtually carbon-neutral, sustainable and renewable energy source.

But if you don't use your Wood Burning Stove properly it can be an expensive, dirty, inefficient and dangerous way to heat your home.

What is a Wood Burning Stove?

A wood-burning stove is a live fire in a metal box inside your home.

Set fire to wood and it burns with oxygen to give off heat and the mixture of waste particles and noxious gases we call smoke.

Outside, burning wood uses oxygen from surrounding air and the smoke blows away in the wind.

Inside we need to control the fires oxygen supply and waste gases.

Because the fire takes the oxygen from the air, it needs a constant supply of fresh air, we call this ventilation.

The fire's smoke needs to be safely removed, we call this flueing.

Ventilation

Burning wood needs oxygen, we need to breathe oxygen, both us and the stove get our oxygen from the air in the room. If the fire uses all the oxygen in the room we will suffocate. Ventilation is the way oxygen is supplied to the fire.

Flueing

Being in a smoke-filled room is uncomfortable and dangerous, modern Wood Burning Stoves are designed to safely remove waste gases and smoke using a large pipe called a flue. This can be inserted inside the existing chimney, fitted on an outside wall or piped up through the roof.

If using an existing chimney it will have to be swept and inspected for blockages and any defects. You will need to select the right kind and size of flue for your stove and know how to fit it correctly.

More about flueing

 A flues job is to:

• Move all the smoke outside.
• Do so without setting fire to your home.
• Prevent condensation of water vapour.
• Prevent smoke from spilling into the room.

For every Kilogram of wood burned the flue has to move, along with the waste gases and smoke, approximately two cubic meters of water vapour and eight cubic meters of nitrogen, up and out of your home.

Flue Height:

A stoves flue should always exit higher than the roof of your home, this is because it uses the warm air travelling upwards to pull fresh cold air into the burner from below.

A flue exit sited too low can result in the smoke from the stove being trapped in the flue and backing up into the room (spillage).

Flue Temperature:

The hotter the waste gases & smoke the faster they rise in the flue, the cooler they are the slower they will rise, if cooled enough, they stop rising and the smoke spills back into the room.

The flue gases must be kept as hot as possible, but new energy-efficient appliances extract as much heat as possible from the stove resulting in a cooler smoke.

To deal with this your flue must have high insulating characteristics to keep the smoke as warm as possible, fast travelling smoke will also prevent the inside of your chimney flue from overheating reducing the risk of chimney fires.

The critical flue temperature is 121°C (250°C ). If the flue falls below this temperature creosote will start to condense out of the smoke onto the flue.

Flueing Water Vapour:

As water vapour is produced by burning wood (2m³ per Kg), condensation in the flue is an issue.

If the flue is properly insulated it will keep the heat inside and the heated water vapour will pass harmlessly up the flue. But if it cools below its dew point (40ºC)  water will condense in the flue.

If using a wood-burning stove with an existing chimney:

Class 1:-  Those with a Brick Stack above the roof and are about 7 inches in diameter.

Pre 1964 Houses usually have class 1 brick-built unlined chimneys, these can leak smoke into the house and have lots of ledges, nooks & crannies for creosote to build up in, increasing the risk of chimney fires.

We advise that all pre-1964 chimneys should be lined with a flue insert.

Post-1964 Houses usually have a concrete lining, some may even have steel inserts but will still be about 7 inches in diameter.

If you are planning on using a class 1 chimney as a flue, it must be swept first and then thoroughly inspected.

Even if the concrete lining looks intact to the naked eye, it's been sitting there for 40 years or so and when you start venting hot gases cracks can open up and bits fall off leading to leaks and possible fire.

Class 2:- Used in either an older house, where the existing chimney has been lined by a  steel flue or a newer house with a steel flue built-in.

This chimney type has a 5”  diameter flue and a steel flue terminal. These must be cleaned then inspected for cracks, holes and gaps before use, if they are faulty then a new flue must be run.

The safest option is to always use a new flue liner in older houses.

Pre-cast flues:- This is a rectangularly shaped flue that is built into the cavity wall construction as the house is being built.

The roof vent would be either a box-shaped ridge tile or possibly a small diameter stainless steel flue and terminal which protrudes above the roof.

These must never be used for solid fuel fires (precast flues will only tolerate operating temperatures up to 250°C, whilst solid fuel burns at 450+°C.).

If you have a pre-cast cast flue you must seek professional advice and have it inspected to see if it is possible to use a liner or if a new flue has to be run.

It is best to have your chimney professionally evaluated by a HETAS registered engineer to see if it is suitable for your stove or if it's necessary to use a flue.

If you do not have a chimney, or do not wish to use your existing one a flue can be fitted to flue the stove through the roof or can be run up the outside of your building.

Read Less

WARNING DIY installation with a precast flue may result in your house catching fire, seek professional advice first.

 Buying & Installing Your Stove

Modern wood-burning stoves are a massive improvement over open wood fires.

They are cleaner,  more efficient, do not pour smoke or throw sparks into the room.

When considering having a wood-burning stove and flue installed, the first question people always ask us is.

"Can I install a wood-burning stove myself?"

Yes, but as you've seen from the sections on venting and flueing you should only attempt this if you know what you are doing, and are willing to get expert advice first.

Otherwise, we don't recommend DIY, make a mistake and you may not find out until harm is done to yourself or others, or your house catches fire.

This is why any work that affects an existing chimney, such as installing a wood-burning stove or making a new chimney, is considered as building work and comes under the Building Regulations.

Your local authority building control must be notified and they will inspect the installation and issue a certificate of compliance if the works are in accordance with the regulations.

The government have issued 'Approved Document J - Combustion Appliances and Fuel Storage systems' which you can read here, it explains how to comply with the Building Regulations.

Choosing your stove

What to consider before choosing your stove.

Size & heat output:

When choosing a wood-burning stove, it's important to select one that's the right size for the space to be heated.

Too big and you will have a smokey smouldering fire which wastes fuel, too small and no matter how much fuel you put on it, it will not be able to heat your space properly.

You can find out what heat output you need for your space with the calculators on our Heating Costs page.

The Type of Stove

The traditional basic wood burning stove such as   The Clarke Buckingham Cast Iron Multi Fuel Stove loses some efficiency (amount of fuel turned to heat) by producing smoke, which consists mainly of unburnt combustion products.

More advanced stoves use some clever technology to increase efficiency by burning off some of those unburnt combustion products.

Catalytic wood burners:

Waste combustion gases often have both oxygen and fuel remaining, by introducing a catalyst at the top of the burner as the gases enter the flue the gases are relit, this effectively burns the smoke, reducing emissions and increasing efficiency.

The catalyst is usually a honeycomb insert placed in the flue entrance. They need to be replaced every 5 to 10 years.

Clean burning wood burners:

Because of the difficulty of replacing catalysts most modern wood burners have an integral secondary combustion chamber that mixes the exhaust gases with preheated fresh air to burn off otherwise wasted fuel.

The end result is similar to the Catalytic wood burner, with much-reduced emissions and increased fuel efficiency.

Pyrolysing or advanced combustion wood-burning stoves.

Usually called cleanburn. These are designed to work at a high temperature (1000°f + )  to burn any combustible gases and particulates produced by the stove resulting in cleaner emissions.

This is done by forcing heated air into the stove over the fire providing a fresh source of oxygen to the already heated waste gases allowing them to burn off.

Another benefit of this is that the funnelling of hot air towards the front of the wood burner keeps the glass doors clear which gives you a better view of the fire. This effect is sometimes called airwash.

Wood Burner or Multi-fuel burner?

Multi-fuel burning stoves are designed to burn a variety of solid fuels, they can burn wood, smokeless fuels, briquettes, coal, coke, peat and turf.

They differ from wood-burning stoves by having a raised grate with moving bars or a central riddling grate and ashpan. These allow for the removal of ash to maintain effective combustion conditions.

Many wood-burning stoves are engineered so they can be converted to multi-fuel burning stoves with the addition of a grate.

The heat output of a multi-fuel stove is similar to that of a wood-burning stove, the benefit is that as you can use a variety of fuels you can opt for the cheapest available at the time.

When using other fuels always check that they comply with local clean air regulations.

Unless you only intend to burn wood we recommend keeping your fuel options open by getting a multi-fuel burning stove.

Never burn plastics or household waste in a stove, plastics produce lethal gases, including cyanide, and burning household waste can cause residue buildups which increase the risk of flue fires or can block the flue completely.

Installing Your Wood Burning Stove

Caution!

A wood-burning stove is a serious piece of kit, you are bringing a living fire into your home.

Install it badly and at worse, you can burn your house down or cause serious harm to the occupants, even death, so treat stories of how easy it is to DIY with caution.

If you lack the skills or expertise don't attempt it, if someone offers to install it for you and they are not registered as a competent person, you can check the register here, then don't hire them.

Use a professional who does this as their day job and has the necessary experience to install your wood-burning stove correctly and safely. All HETAS engineers are on the competent person's register.

DIY:

If you are a competent builder or a seasoned DIY'er and you want to go ahead please download this official LABC (Local Authority Building Control) technical guide  How to install wood-burning stoves   also familiarise yourself with 'Approved Document J - Combustion Appliances and Fuel Storage systems',

If you do not use a HETAS engineer or are not registered with the Competent Person Scheme then you will have to notify your local authority before you commence work, submit a building notice or full plans application and pay a fee to have a Building Control Body come and inspect the work.

Professional Installation

Due to the dangers which can be caused by improper installation and the legal necessity of having a Certificate of compliance we recommend installation by a HETAS registered engineer.

HETAS is the official body recognized by the Government to approve biomass and solid fuel domestic heating appliances, fuels and services, including the registration of competent installers and servicing businesses.

If you are uncertain about the type of wood-burning stove you need or about siting it, then call for professional advice.

Certificate of compliance.

Regulations require all wood-burning stoves installed after April 2006 to have either a HETAS certificate or building regulation compliance. Failure to do so is an offence that can result in enforcement action being taken against the Householders and /or the installer.

The result can be a fine of up to £5000, it can also invalidate your insurance and you will have difficulties selling your house without a Certificate of compliance for a wood-burning stove installation.

Smoke control areas:

Some authorities have restrictions under the clean air act which control the emission of smoke.

Before ordering your wood-burning stove, check with your local authority to see what its policies are on solid fuel domestic fires.

To comply with these regulations wood-burning stoves have a number of features to reduce harmful emissions and increase heating efficiency. Some are DEFRA (Department for Environment, Food & Rural Affairs) rated as 'for use in smoke control areas'.

You can download the DEFRA practical guide to stoves here

External Ventilation:

As previously mentioned, rooms housing wood-burning Stoves rated over 5 kW need an air vent, If you are concerned about droughts in the room, there are some stoves that are designed to draw in extra air from outside.

The Costs

To Buy

A basic 5 kW multi-fuel burning cast iron stove costs around  £300 plus the cost of installation, there are no electrical components so it can be used safely during a power cut.

Mid-range models costing £300 - £800 should be well designed, clean burn and highly efficient (average 84% when burning seasoned wood).

Stoves should be DEFRA rated for use in smokeless zones so they meet the highest standards for emission control.

Expect to pay £1000+ for top specification stylish contemporary designs such as the Danish Aduro and Slovakian Thorma ranges. These are made to the highest standards and have extensive guarantees.

The Thorma Andorra 5kw stove pictured here costs about £850 plus installation costs.

This one is steel with an 80% efficiency rating, is rotatable, has a concrete storage heater option and a 2-year guarantee.

With top models expect extras such as remote controls, a variety of super-efficient & energy saving tech' as well as cutting-edge design.

Some high specification stoves have active fan extraction/ventilation systems which use electricity and would not be safe to use during a power cut.

Installation Costs 

If you already have a suitable chimney and no additional building alterations are required, the installation costs can be as little as £450 to install the stove in your hearth and run a flue up your chimney.

If you don't have a chimney then an installation can rise to around £1500 (depending on how complex the flueing is). In England & Wales, this is deemed controlled works and will need a certificate of compliance which your HETAS engineer will supply.

Running costs 

From May 1st 2021 UK homes with open fires and wood-burning stoves will no longer be allowed to burn wet wood ( with a moisture content of above 20%) and house coal, sales of wet wood and house coal will be phased out in England from February 2021.

Wood (or other solid fuel) to burn in your stove:  Firewood is usually sold by the cubic metre (M³). For the average British winter, If you use your stove most evenings you’ll probably need 3-4 cubic metres. If you use it all of the time,  then maybe 6 cubic metres or more. Bulk buying high-quality kiln-dried hardwood can work out at around £100 per M³. Source your own wood and it can cost as little as £0.

Routine cleaning: Once a year a  sweep of the flue or chimney is needed to remove the creosote and soot build-up, this may mean hiring a chimney sweep once a year, the cost should be well under £100.

Maintenance: Emptying the ash pan and cleaning the exterior regularly costs nothing,  you can use an Ash carrier to minimise mess or treat yourself to an ash vacuum cleaner which makes it easier and cleaner. With a cast-iron stove, you may want to use graphite polish to preserve the silver-black finish.

Other costs: More hi-tech models may use a small amount of electricity to run a fan and remote controls.

Using Your Stove

Congratulations, you've read this guide and now decided to invest in a wood-burning stove and start reducing your heating bills.

Warning

While it is tempting to use old bits of wood and builders debris to save money (after all it's free), this will cause serious issues because painted and varnished wood give off toxic fumes and causes build-ups in the flue.

Burning MDF, chipboard or other man-made boards causes flue build-up from the resins used to bond the wood fibres together, the smoke emitted also contains hydrochloric acid which attacks both steel flues and concrete chimney liners.

Waste builders wood contains nails, staples and other bits of non-combustible scrap which can cause damage to the burner and harm you when cleaning out the stove.

Wood picked up from parks, woods etc... are full of moisture and unless dried out will not burn properly resulting in a smokey inefficient fire.

The key to using a wood-burning stove effectively is to manage  3 things:

1. The Fuel:

The moisture content of wood determines how much heat the fire puts out and how much creosote will build up in your flue. Burning green (unseasoned) wood means boiling the water out of it before it starts to burn properly, you may as well pour water into your lit fire.

Unseasoned wood can have a moisture content of up to 90%, burning it will cut the efficiency of your wood burning stove by three-quarters and cause heavy creosote build up in the flue, creosote burns at about 2000° F. You do not want loads of this flammable goo stuck to the inside of your flue!

Using unseasoned wood takes all the pleasure out of using a  wood burning stove; it's hard to light and goes out often. When lit it tends to smoulder giving off little heat, many people who complain about the disappointing performance of their wood burning stoves are doing so because they are using the wrong kind of wood.

Dry seasoned wood with a moisture content below 20%  is the only wood suitable for use in wood-burning stoves.  From May 1st 2021 it will be illegal to burn woods with above 20% moisture content in your stove or open home fire.

2.The Ash Bed:

To get a  wood-burner working well you need to get a good hot ash bed, the wood then sits on the bed of hot ash and a  chemical reaction takes place (Pyrolysis). This carbonises the wood (turns it to charcoal) which burns to form the hot base and releases flammable products such as Methane (CH4)  Hydrogen gas (H₂) and tars from the wood which then burn as flames and generate heat.

3.The Air supply: 

Once you have established a hot ash bed pyrolysis does not need much oxygen to get the wood hot enough to release flammable gases,  these are the gases that burn as flames and will need their own oxygen supply.

Ensure the upper part of the fire has a good supply of air. Closing the upper (secondary) vent of the stove will result in incomplete combustion, the gases will not burn properly and will be deposited as soot and creosote inside your stove and flue, wasting fuel.

Manage these 3 things correctly and you will have a well working, clean-burning stove, working at maximum efficiency.

Using The Stove

Piling logs into your stove to keep a roaring fire going is the wrong approach, wood-burning stoves are intended for intermittent combustion.

This means letting the wood burn down to embers before new logs are added. To obtain the best possible combustion, you should use the fuel to regulate the heat output.

• Size - Burning small logs provides more powerful combustion than burning large logs as the surface area is greater and more flammable gas is released.
• Quantity - The ideal heat output is reached by burning approx. 1.3 kg per hour (this will vary depending on the size of the firebox).

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First Lighting

The first few times the wood-burning stove is used, there may be some smoke and unpleasant odours, which is normal and caused by the heat-resistant paint hardening.

Make sure there is sufficient ventilation during this stage. It is also important not to let the fire burn too fiercely the first 2-3 times so that the stove has time to expand slowly, too hot first firings can cause it to crack.

Lighting the stove

The fire lighting method is very important for starting combustion quickly and efficiently.

1. Open the primary damper at the bottom of the door and the secondary damper at the top of the door.

2. Place a log of wood crosswise in the combustion chamber and put 2 firelighters close to the log. Light the firelighters and quickly put a new log close to the firelighters and several small logs at an angle above it. Air must be able to reach the firelighters, but the logs should be touching to “warm” each other. If you are not using firelighters start your kindling fire and build up the logs in the same way around the kindling fire as you would with the firelighters.

3. Keep the door approx. 1 cm ajar, until the glass is too hot to touch. Then close the door. When there
are distinct, visible flames and the fire has taken hold, close the primary air intake/damper.

Hardwood or softwood?

Opinions vary on this and on the benefits and pitfalls of using wood from various trees, but in reality, the choice of wood depends on which kind of fire you want:

For a slow long-lasting fire use hardwood, for a quick hot burning fire use softwood.

As Hardwood burns slower than softwood it gives a more even burn and constant heat, another advantage of hardwood is it produces more ash, this aids pyrolysis.

If you want a quick-burning softwood fire,  after kindling put down a layer of hardwood to build a nice hot ash bed, then feed it with softwood.

For all types of fire use softwood kindling to start it as it burns faster than hardwood it is easier to get the fire started and up to heat.

Layer your stove like this: Softwood kindling, then hardwood to build an ash bed, feed with hardwood for an even burning slow fire, or feed with softwood for a quick burning hot fire.

Hardwood in the UK is obtained from slow-growing broadleaf deciduous trees such as Oak, Ash, Birch, Elm & Beech. Softwood comes from conifers such as Pine, Cedar, Spruce and Yew.

It's worth getting to know your trees so when gathering you can sort out your woods into hard and soft piles.

Good quality seasoned hardwood produces about 4.5kWh per Kilo, unseasoned wood produces about 1 kWh per Kilo.

Wood Management

The cost of running your stove is the cost of the wood supply, sourcing free wood is the key to saving money.

To get the best value from your stove you need to gather and season your own wood, this needs to be done sensibly, chopping down the trees in your local park for fuel is illegal.

Sources of legal free wood are all around.

The first place to look is your neighbours, let anyone with a garden know that if they are pruning trees you will remove the wood for free.

Smaller pieces can be used for kindling, larger logs will form part of your wood store.

When you see tree surgeons working, ask them for a few logs before they throw them in those giant shredders.

If you can strike up a rapport with a local gardening company, you may be able to get a constant supply from them for free.

Only glean for dead wood in your local parks or woodland after getting permission from landowners or relevant authorities as some councils and land management bodies have strict rules on removal of wood from their property.

Preparing the wood:

Water in wood is trapped in microscopic tubes, these need to be dried out, the quickest way to do this (and the most expensive) is to dry the wood in a kiln.

The traditional (and free) way is to season wood by leaving outside and letting the wind penetrate the wood, chasing out the trapped water.

Any wood you gather must be seasoned for at least 2 years, this is how long it takes to dry out properly, 1-year-old seasoned wood still has a significant moisture content.

To do this you need to make a woodpile:

Find a suitable space in your garden or yard, the more exposed to the wind the better.

Your woodpile needs to be raised off the ground, a couple of builders pallets are ideal for the base, then stack the wood so it is end on to the wind, allowing the air to flow through it.

Rotating your wood supply:

This is how you eventually cut your fuel costs to zero

At the end of year one start a second woodpile, at the end of year two woodpile no. 1 is ready for use.

Cut the wood from woodpile 1 into the right size bits for burning in your stove and put them onto your log pile, you should have enough to see you through year three.

Restart the woodpile and repeat this every year.

Reducing your Heating Bill by up to 90%

You should now know how to:

• Choose a wood-burning stove suitable for your needs.
• Get it installed safely.
• Source and manage a free wood supply.
• Use your wood-burning stove properly to get maximum heat output.
• Be able to enjoy cheap effective heating.

There is more you can do, the stove is only installed in one room, how about sharing the benefits of free fuelled heating to the rest of your house and using it to heat water for bathing, washing dishes etc...?

If you live in a cosy bungalow or flat one wood-burning stove may be all you need.

Using a heat-driven stove fan, leaving the internal doors open and following the advice on our energy saving page will allow the heat from your wood-burning stove to circulate through your home.

However this is not practical in a 3 story house on a cold winters day, that's why we went from open fires to central heating, one central boiler supplies heat to radiators that heat every room in the house.

And you can run your entire central heating and hot water system from your wood-burning stove

Many stoves have back boilers and are designed to drive hot water central heating systems.

There are plenty to chose from whatever your lifestyle. Over half of all solid fuel boilers in Europe use wood, most of the boilers we recommend come from established European manufacturers such as NES Ltd of Bulgaria, who have decades of expertise in making them.

Traditional cast iron models such as the entry-level  8kw  Castmaster Belvoir Stove Boiler priced at £499, the same price as a mid-range wood burning stove.

It will provide 4kW of heat to the room and 8kW to the water system, enough to supply a 120-litre hot water tank and 4 medium radiators.

High spec high powered dedicated boilers such as the  BURNiT  WBS range available in sizes from 20kW to 110kW (this will easily power the heating for a large family house).

.AGA style range cookers combine kitchen hobs and ovens with stoves and central heating boilers.

A new AGA Rayburn supreme can heat up to 10 radiators and will cost around £3000,  pre-owned ones are available for much less. Try Preloved for hassle and fee-free buying from other householders.

There are cheaper alternatives and we have listed some in our Wood Burning  Range Cooker section.

As with any heating system you may have to  occasionally use a portable heater  to deal with cold spots or for quickly heating a specific area (such as a cold bathroom), have a look at The Home Heating Shop for suggestions

We recommend contacting your local HEATAS engineer and asking them to have a look at your existing home heating setup. They will advise you on the best  Wood burning stove boiler option for your home.

If you follow our guide your main home heating will only cost you the time it takes to gather wood and you will see a reduction of up to 90% in heating energy bills.

What size Boiler Will You Need

To calculate the right boiler size for your home it is best to ask a heating professional to visit and advise you as there are many factors such as the size and number of your radiators, the level of insulation in your house, the size of your hot water tank and your level of hot water usage etc...

To give you a  rough idea of what size you may need you can follow these steps to calculate the heat output of radiators needed for each room, heat output is measured in British Thermal Units (BTU), 1kW  of heat output = approx 3400 BTUs.

How to calculate the size radiators you need.

Measure the length, width and height of each room in feet. Multiply all three values to get the cubic footage of the space.

For example, if you have a room that measures 12 feet long by 10 feet wide by 7 feet high, multiplying 12 by 10 by 7 produces 840 cubic feet.

Then for

• Lounges and dining rooms Multiply cubic feet by 5
• Bedrooms Multiply cubic feet by 4
• Common areas and kitchens Multiply cubic feet by 3
• For rooms facing north Add 15%
• For French windows Add 20%
• For double-glazing Deduct 10%

Then add the total of each room together and then add 20% to the total for a hot water circulating tank and 10% for general losses. This will give you the boiler size in BTU you need for your house.

To convert BTU to kW multiply the total by  0.000293

These calculations will you a general idea of the boiler size you will require, but get your home checked by the installer before you buy your boiler.

If you want to convert from  gas  central heating using the already fitted radiators the approximate heat values per radiator are:

• 120-litre domestic heat water tank - 2.6k (9,000 BTU)
• 600mm x1200mm double radiator - 2kW (7.030BTU)
• 600mm x 1000mm double radiator -1.7kW (5,850 BTU)
• 600mm x 800mm double radiator - 1.4kW (4,680 BTU)
• 600mm x 600mm double radiator -1kW (3,510 BTU)