wood burning stoves – overview

Measuring the efficiency of a stove is difficult, for the public it is impossible. As a layman you would think that if you buy an 8kW stove which is 50% efficient you will get 4kW of heat. Wrong. The efficiency indicates how complete (or clean) the combustion is and the kW rating is how much wood the stove burns every hour. Neither have any relevance to how much heat ends up in the room. To create a stove which heats effectively, you need high efficiency and an effective means to extract the heat before it is lost up the chimney.

 

image of biomass boiler

Perfect combustion of wood

Burning wood efficiently requires a three part process –  a primary, secondary and tertiary combustion process.

Primary combustion
Primary combustion is the initial burning of the wood at relatively low temperatures. During primary burn, water is evaporated and large amounts of creosote gas are produced. This creosote holds 60% of the potential energy of the wood, but it is deposited on the inside of the stove and the lining of the chimney.

Secondary combustion
If the combustion chamber is insulated sufficiently to raise the core temperature and exactly the correct amount of oxygen is introduced, at 600oC the creosote spontaneously combusts. This creates a chain reaction which increases the temperature inside the stove from 600oC to 900oC with no extra use of fuel. This is the secondary burn.

Tertiary combustion
Tertiary combustion occurs by fully burning the carbon, charcoal and ash which is left behind. These contain a huge amount of energy and provide a long rate of heat. Anyone who has barbequed will be aware of how much heat is present in semi-combusted wood. Blacksmiths melt steel on it.

With high efficiency stoves, 100kg of wood can be reduced to 1 pint of ash (a ratio of 350:1) which is simply scooped out. No more carrying bucket loads of ash through the house every time you want a fire.

Why choose a room sealed stove?

The majority of wood burners draw their air from the room, often through vents at the top or bottom of the door. Whilst this is a very cheap and simple method, it is also very inefficient and results in comparatively poor combustion. Drawing air from the front of the fire for combustion means that you are dragging huge amounts of warm air from the room (which you have already paid to heat) and losing it up the chimney. This is replaced by cold air from outside, creeping around windows and under doors, chilling your living room.

Room sealed stoves draw all their air through a vent at the rear where it is ducted to the outside. This way it only draws cold air from outside. All the lovely heat stays in your room. British standards dictate that any room with a stove rated greater than 5kW must have an air vent fitted. With the room sealing kit fitted to the stove you do not need to fit a vent in the room, conserving yet more energy.

Where possible it always pays to room seal a stove. The average chimney will drag all the warm air from a room once every single hour. There is an increasing range of stove models which can be room sealed through an outside wall to completely eliminate this heat loss. This alone can add up to 50% additional efficiency to an open vented stove.

what is biomass

what is biomass?

Biomass is biological material derived from living, or recently living organisms. In the context of biomass for energy this is often used to mean plant based material, but biomass can equally apply to both animal and vegetable derived material.

why use biomass?

why use biomass?

Biomass is a renewable, low carbon fuel that is already widely available throughout the UK. Its production and use also brings additional environmental and social benefits.

but is it really sustainable?

but is it really sustainable?

Yes! As plants grow, each molecule of carbon dioxide they absorb from the air ends up as one atom of carbon in the plant, and two atoms of oxygen which are returned to the atmosphere. When the biomass is burned, each atom of carbon combines with two atoms of oxygen to give one molecule of carbon dioxide.

what type of boiler?

what type of boiler?

There are many different types of biomass boilers available, to suit every application so it may be easiest to first consider the three different types of fuel – wood pellets, wood chip & logs.

biomass is often chosen for older houses requiring large amounts of heat

Take advantage of the Renewable Heat Incentive to cover the cost of your transition to biomass. With the current Domestic RHI payments set at £0.122 per KWh, this could mean annual payments of over £3,000, for 7 years, for a standard family house with a heating requirement of 25,000KWh indicated on the EPC.

Combine this with interest free loans, significantly reduced fuel costs when compared to oil, LPG or electricity, the financial arguments to transition to biomass, are worthy of very serious consideration. To find out more click here, or get in touch.

For Non-Domestic installations the RHI payments last for 20 years and the return on investment can be very significant. For a more detailed explanation click here, or give us a call and we can talk you through it.

how it works

Take a look at how biomass technology works in detail…

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running costs

See how the running costs stack up against your current system, in light of the Renewable Heat Incentive & 0% loans…

considerations

There are many practical, financial and ethical issues to consider when getting a new heating system for your home…

buying a biomass system from us

This section will take you through the steps involved in safely buying a biomass system…

biomass is often chosen for older houses requiring large amounts of heat

Take advantage of the Renewable Heat Incentive to cover the cost of your transition to biomass. With the current Domestic RHI payments set at £0.122 per KWh, this could mean annual payments of over £3,000, for 7 years, for a standard family house with a heating requirement of 25,000KWh indicated on the EPC. Combine this with interest free loans, significantly reduced fuel costs when compared to oil, LPG or electricity, the financial arguments to transition to biomass, are worthy of very serious consideration. To find out more click here, or get in touch. For Non-Domestic installations the RHI payments last for 20 years and the return on investment can be very significant. For a more detailed explanation click here, or give us a call and we can talk you through it.

we are MCS Approved Installers and members of the Renewable Energy Consumer Code

Based in the Scottish Borders and operating in Scotland's Central Belt area, we aim to offer you the best advice, products and prices with a quality installation service from our friendly team. We take pride in operating to the highest technical and ethical standards!

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what we do

Green Star Energy Solutions Ltd. is a is a company that specialises in taking a holistic look at the specific energy requirements of your home or business and matching this to a perfect renewable solution, where viable.

We are a small renewable energy company, whoes objective is to reduce the energy bills of rural householders and businesses, enabling our clients to capitalise on the RHI and other government incentives, while reducing their CO2 emmissions.

As a new company, reputation is everything to us, and we aim to earn a the best reputation, and exceed the expectations of our clients. We were established in 2014, with the main objective of addressing the large number of properties in the central belt that do not have access to mains gas, and are running on oil of electric heating systems.

With the introduction of The RHI in April 2014, it has never before been so financially beneficial for house holders and businesses to move over to renewables – we’d like you to help you with this transition!