Log Burning Stoves with Backboilers
If you provide your heating and hot water by using a log burning stove with a back boiler, then when you burn the logs the only CO2 that is released is the CO2 which the tree absorbed during its lifetime. If the logs are sustainably sourced then the tree that was felled has been replaced by another resulting overall in no net CO2 gain.
Of course, in order to burn logs on a log burner, the trees have to felled and turned into logs and transported , which of course results in some emissions, but these are fairly insignificant when compared to the CO2 emissions that result from heating a house with coal, oil, or gas. Burning logs is a very significant way of reducing your CO2 emissions to combat climate change, particularly if the stove has a back boiler, so that it not only heats your home, but supplies hot water. Of course there are other things to consider before installing a log burning boielr stove, for example you should make sure your house is well insulated so that it does not require much heating anyway. Read more about ways to be energy efficient.
If you have not used log burning stoves before, there are a few other things to consider first. You should also think about where and how you source your logs, where you store them and how well they are seasoned. Learn more about this on our firewood page.
Air Supply for Combustion in a Log Burning Stoves
A dedicated woodburner will be efficient at burning logs. A stove burning logs requires combustion air to enter the firebox from the top. When the logs heat up they release gases and it is these that create the majority of the heat and flame in the firebox of the stove. If the supply of air only comes from under the logs then the oxygen will often get used up before all these gases are burnt thus wasting heat. A well designed log burning stove therefore introduces a good supply of air above the logs, (often preheated air), to burn off these gases. This increases efficiency and also increases the heat output of the stove.
Logburning Stove Firebox Size
It is often easier to use a logburning stove with a large firebox - this lets you burn longer and larger logs in the stove. Often logs come in various shapes and sizes and it can be difficult to source logs that are all the perfect size for fitting into a woodburning stove with a small firebox. So when you come to choose your stove, (even if you are choosing one without a back boiler), then think about the size and type of logs which you will be using.
Grates in Log Burners
Logburners will often be designed without a grate, although some do. Wood burns well on a bed of ash as this provides a well insulated base for the logs to burn on. This helps to bring the firebox temperature up which helps in turn to increase the stoveís efficiency. Bringing the firebox temperature up is especially important in log burning stoves with a back boiler as the water in the backboiler will tend to cool the firebox down a little. We recommend using a heat charger.
Heat Chargers for Log Burning Stoves with Back Boilers
The backboiler in a stove is cooler than the firebricks or linings that make up the rest of the firebox. This is because the water in the back boiler will generally be within a temperature range of 20-90 degrees or so. The faster that this water can reach an operational temperature of around 60-70 degrees the better - with the water in the backboiler at this sort of temperature the firebox temperature in the log burner also rises and burning becomes more efficient.
The problem is that there is often a significant volume of water to heat in a central heating system and so it can take quite a while for the log burner to heat up the water to this temperature. This is where a heat charger comes in handy. Read more on our Laddomat heat charger page.