Wood Burners

Why Have Woodburning Stoves Recently Become So Popular?

Top of the list in equal first place must be: significant savings in running costs with constantly rising prices for gas, oil and electricity; and good looks. Most everyone loves that traditional fireplace effect and the cosy warmth that more conventional forms of space heating just seem to lack.

Modern wood burners are very energy efficient and the price of the fuel compares extremely favourably with fossil fuel alternatives with potential energy savings at between 3 to 8 times depending on the exact comparison and location. They are also very clean and easy to use and maintain.

Whether you want a stylish ultra modern look or a traditional country kitchen style there’s a wood burning stove to suit your lifestyle – the choice is simply enormous. No matter what you choose though, wood burners always add a nice homely touch and people somehow seem to gravitate towards them.

The other main factor in favour of installing wood burning stoves is that they are very environmentally friendly. Oddly, many people would assume the exact opposite since they can see that a wood burning stove is clearly burning wood and creating smoke that contains carbon emissions. They tend to overlook that the “clean” electricity that enters their house has itself been created by burning fuel – almost always a fossil fuel such as coal, gas or oil.

The main difference between the two is that wood, unlike fossil fuels, is renewable and in the course of growing new wood (i.e. trees) carbon is extracted from the atmosphere and locked back up inside the wood. The carbon in a tree is eventually released back into the atmosphere regardless, so burning it releases no more carbon than leaving it to rot. It is a more or less balanced carbon cycle.

It is for this very reason that many architects and builders now incorporate energy saving wood burners in their designs for new buildings - it enables them to simultaneously provide an economical and aesthetically pleasing domestic space heating, hot water and optional cooking solution and much more easily comply with ever tougher regulations targeting low carbon emissions.

Woodburners, BioFuel And Climate Change

Woodburners use what is called “woody biomass” as fuel. Biomass (also often called biofuel) encompasses two principal categories: woody biomass (which is exactly what it sounds like) and non-woody biomass which is everything else including various sorts of biodegradable waste material and crops intentionally grown as biofuel, for example sugar and maize.

Woody biomass fuel suitable for use in a woodburning stove is typically wood pellets, wood chips and wood logs. Many modern wood burning stoves are described as “dual-fire” meaning that they are capable of being run by any of these fuels (wood biomass pellets are similar in size and appearance to the sort of thing people feed pet rabbits but made from highly compressed sawdust).

Dual-fire burners are not to be confused with “multi-fuel” stoves which are capable of burning both wood products and coal. While it might be convenient to use coal as a fuel - not least because unlike wood which should be burned “fast” it can be slowly burned - coal is extremely environmentally hostile. Coal is, hands down, far and away the worst fuel as regards CO2 pollution, beating both oil and gas by a considerable margin. Although the Climate Change Levy (a tax on energy designed to encourage energy efficiency and reduce carbon dioxide emissions) does not at present apply to domestic energy users, it is still worth noting that while wood fuel is exempt, coal is most certainly not.

Basic Checklist Before Considering Installing a Wood Burning Stove

There are various pros and cons involved with installing a wood burning stove and some of the crucial issues to consider for any biomass system are as follows.

First, check availability of solid fuel in your area; are there any local suppliers of wood pellets, wood chips and/or logs. Do you have sufficient suitable trees to provide your own logs, bearing in mind that wood intended to be used in a wood burning stove should be fully seasoned (left to dry naturally for at least a year) and that you should plan to replace any trees you harvest for biofuel.

Be very wary of burning wood whose source is unclear; it may contain excessive moisture which will foul your flue or worse may have been treated with preservatives or other substances that are hazardous to health when burnt.

The costs to run wood burners and the environmental benefits from installing wood burners both suffer badly if bulky and heavy wood fuel has to be transported any significant distance.

Second, ensure that you have somewhere to store the fuel since it is bulky and needs to be kept dry, and also check that you have adequate access to the wood burner (or the fuel hopper if you have installed an automatic fuel loading system) in order to load it with your intended biofuel. You don’t want to be having deliveries of wood every fortnight or so and you don’t want to struggle getting the wood to the burner. A covered space at least three cubic metres in size and relatively close to the wood burner is what you should aim for if your wood burning stove is to be an easy to use, cost effective alternative to conventional heating systems rather than a millstone around your neck. If you are sourcing your own wood then this must be well seasoned (left to dry naturally for a couple of years).

Third, with wood burning boiler stoves it is important to optimise the heat load, in other words to burn the fuel at a fast rate and high temperature in order to achieve optimal efficiency - running a wood burner in “tick over” mode can cause easily tarring of the flue. Obviously this requirement can present a problem since it’s unlikely you would want that much heat generated all the time. The solution for many is to install what is called an accumulator tank, which acts like a heat battery, storing the accumulated heat as very hot water which can then be released over the next day or so (typically into the house radiators and hot water system).

Fourth, bear in mind that a domestic wood burning stove requires a flue and that the vent material must be suitable for wood fuel applications. There must also be proper air movement to ensure correct operation of the stove. If you already have a chimney then it is possible to have this fitted with a lined flue suitable for a wood burner, but again this costs extra money.

However, some would go so far as to assert that the most important component of a wood burner installation is not the wood burning stove itself but the chimney! It is vital to keep the flue gasses hot which means an insulated flue, usually using either a steel liner or a lightweight aerated concrete lining, must be installed otherwise there is risk of accumulating tar deposits in the chimney.

On the subject of the chimney, remember that these need to be kept clean in order to function safely and efficiently, so find yourself a reputable local chimney sweep.

Finally, there are all manner of regulations you will likely need to check to ensure compliance and to ensure you can make full use of any grants and incentives that may be available to offset your installation costs. These are covered immediately below.

Regulations Governing Installation Of Wood Burning Stoves

Obviously the physical installation or the wood burner itself needs to comply with safety and building regulations. Also, you might need planning permission to fit a twin wall flue if you don’t already have a flue or suitable chimney. And of course, with recent Climate Change legislation you might also need to establish compliance with the Building Regulations Part L - Conservation of fuel and power (the UK implementation of the EU Energy Performance of Buildings Directive).

If you plan to install a wood burning boiler or stove in an urban environment in general, or are located in a smokeless zone, you will need to check which regulations apply, what exemptions might also apply and consider specially approved wood burning stoves that have been designed to comply with the Clean Air Act with regard to particulate pollution. In the UK you can easily check the location of Smoke Control Areas and also which types of wood burning appliances and specific fuels are exempt.

Grants and Incentives for Installing Wood Burning Stoves

Don’t forget to check whether you are eligible for incentive grants towards the cost of installing your wood burning stove. There are numerous government sponsored schemes and aid grants aimed at encouraging people to install environmentally friendly technologies such as wood burning stoves and wood burning boilers. You could be pleasantly surprised at not only the cost savings from operating your wood burner, but also the amount of financial assistance towards the initial installation costs you might be eligible for. In the UK these grant schemes are operated under the Low Carbon Buildings Programme (LCBP).

The UK government agency DEFRA (Department for Environment, Food and Rural Affairs) considers wood chip boilers to be the most cost-effective microgeneration technology in terms of energy saving potential and award financial incentives for installing wood burning systems. Under the terms of the LCBP, which is administered by DEFRA, the maximum grant available in the UK is £1500 (regardless of the size of the wood boiler) with an overall limit of 30% of the total cost (exclusive of VAT).

In the UK, you can go your own way and apply to your local authority building control department for a building notice which will cost anything up to about £300. Upon completion of your wood burner installation, you will also have to notify the authority who will inspect your installation to ensure it is fully compliant with building regulations. Failure to comply can lead to enforcement and serious problems for future house sale and can be unpleasantly expensive to rectify.

Needless to say, most people quite sensibly adopt the easier and safer route of employing a HETAS registered installer who will not only install your wood burner but also issue a Certificate of Compliance and notify the local authority on your behalf. Finding a reputable approved installer to both plan and carry out your wood burner installation is simply a matter of choosing a local installer from the list of approved solid fuel installers at the HETAS website. HETAS is an acronym for Heating Equipment Testing and Approval Scheme and any local HETAS accredited installer of wood burners should be able to provide answers and advice relating to supply of wood, installation options, local regulations and how to apply for grants.

Types Of Wood Burner Installation

As well as there being a huge number of manufacturers of domestic wood burners, there is also a bewildering variety of different types of wood burner. There are also many ways to use biomass systems such as wood burning boilers and stoves to to provide domestic heating and/or hot water, but to keep things simple we’ll divide things into three main categories: traditional stand-alone wood burning stoves, biomass boilers and wood burning cookers (often in the guise of traditional kitchen ranges).

There is obviously considerable overlap within these main groups; both wood burning stoves intended as room heaters (or space heating stoves) and cookers for example may be further subdivided into those with and those without wood burning boilers. There is then a further permutation to consider, which is whether or not the burner is designed to run on wood biomass pellets (properly dried and sized wood chips may also suffice).

A basic stand-alone wood burning stove provides very effective space heating for a single room, much like an open fireplace but rather more attractive, safe, clean, efficient and easier to maintain. Indeed, many people do install stand-alone wood burners in fireplaces as an alternative to an open fire. Regardless of location though, these are principally intended for localized space heating and to act as a feature or focal point in a living area.

Larger domestic wood burner systems are able to heat an entire house, in addition to providing a certain amount of local heat. These are wood burning or biomass boilers and as you might have guessed they operate by heating water which is then passed to the regular domestic radiators and usually also the main hot water cylinder.

An alternative configuration for a wood burning boiler is to heat then store water in what is termed a “heat accumulator” (similar in many respects to a hot water cylinder tank but larger and able to maintain effective water temperatures for several days.

The main reasons for opting for an accumulator are a) it is more efficient to run a wood burner fast, aiming to fully burn all the fuel present, but this then produces an excess of heat (converted into hot water) which needs to be stored for subsequent use, and b) it is also a good option for storing heat generated during the day if you also have some form of solar energy system installed. Accumulators generally have multiple “tapping points” (ways to connect heat sources) so they are ideal for storing heat supplied from say solar panels, wood burning stoves, conventional gas boilers, and so on).

There are also wood burning stoves that provide full cooking capabilities. Many are simply wood burning stoves where the heat is used to heat ovens and hobs but some models are more than capable of providing all domestic hot water and radiator heating for the whole of a large family house as well as localized space heating in the kitchen due to background heat from the oven and hobs. These are typically styled as traditional range cookers (think Aga and Rayburn) but in place of one of the main ovens is a boiler.

Modern whole house wood burner systems are often designed as a complete replacement for an existing gas, oil or electric heating system (or installed from scratch in new builds) and have every modern convenience you would expect including automatic loading hoppers, automatic ignition, programmable timer settings, remote control and full heat adjustment. The superb Belgian Saey range of wood burning stoves includes many such fine examples that look absolutely beautiful too.

The principal differences between wood burners such as these and conventional (usually gas) boilers are that they cost a great deal less to run and they are significantly more environmentally friendly since wood burning is a sustainable, close to carbon-neutral process. They’re a great deal more attractive as well, which is why you will almost always find a wood burner installed as a prominent feature in most homes, rather than hidden away in a cupboard or utility room.

Cost to Install a Wood Burner

Many people ask how much it costs to install a wood burner. This is a lot like asking how much it costs to build a house. It depends on what you want, what your budget is, how much space you need to heat, what type of heat you need (space heating, hot water, cooking, a combination thereof), what restrictions might apply and so on. There is no set answer because as you have already discovered there is no one definitive “wood burner”.

The term wood burner (and associated terms such as woodburning stove, wood boiler, wood burning cooker and so on) is generic and applied loosely to a whole class of different individual styles and makes of wood burner. Each costing different amounts to purchase, install, operate and maintain.

That said, as an extremely general example, a 20kW (which is approximately the size needed for a typical three-bedroom house) wood pellet boiler with automatic fuel hopper could cost around £5000 including all installation costs (i.e. including the cost of the flue and commissioning the boiler). The same size wood boiler system using a manual log feed would obviously come in slightly cheaper.

Unless you are highly competent at DIY and qualified to perform (and, all too often these day, also certify) the necessary work to install a wood burner then you should seek the advice and services of an approved heating engineer (as noted above). A qualified specialist should be able to provide an approximate idea of the type of wood burning system best suited to your requirements and typical costs to purchase, install and run such a wood burner.

Certainly beware buying a wood burner online. By all means use the internet to research wood burning stoves and get an idea of what’s available at what price and generally compare wood burning options; but at the end of the day you are always best advised to buy face to face from a reputable supplier with a physical address, a track record of happy customers and a reputation to protect. Whatever you think you might save by buying online, the truth is you will save many times over by dealing with an experienced professional company who understand the surprising complexities and potential pitfalls involved with installing wood burning stoves.

Integrating A Wood Burning Boiler With An Existing System

Of course, not everyone has the luxury of installing a brand new wood burning system into a new build. Most people are looking to install a wood burner either as a replacement for, or to operate in combination with, an existing gas boiler. Even those who are installing a new wood burning stove might consider installing a combination of wood burning and gas boiler (plus possibly also solar water heating). In an uncertain world it makes a lot of financial sense to adopt more than one technology.

Pretty much the first problem that most folk run into when attempting to integrate wood burning stoves and/or solar powered heating with existing, typically mains gas, heating systems is differences in design and particularly pressures within these various systems.

Most modern gas boilers are combination (or combi) boilers that are closed, pressurised systems, whereas the backboiler typically fitted (as the name suggests) to the back of most wood burning stoves is designed to feed a conventional gravity fed hot water cylinder and cannot withstand the pressure within a closed system. This is not to say that you cannot integrate a combi boiler and a wood burning back boiler. Some back boilers are designed to withstand the pressures in a sealed system - this type of installation has a pressure relief safety valve fitted to protect the back boiler.

However, as a general rule most wood burning stoves must be connected to an open vented system, and although the primary circuit may be pumped, it must be capable of dissipating heat from the wood burning stove by natural gravity circulation in case of a power or pump failure (the heat is usually sent to a thermal store or bled directly into the house radiators). The easiest option for many is to incorporate a thermal store (i.e. a heat accumulator) with a device for combining feeds from mains pressure combi boilers with those from renewable energy sources (solar thermal systems and wood burning stoves); the Grant CombiSOL is a well known example.

Installing a wood burning stove is not a light undertaking, but if you approach the idea with realistic expectations you stand a very good chance of reaping the very considerable benefits for many years to come.