It’s almost been nine months since the official launch of the Ecodesign Ready initiative. Back in February this year there was significant coverage about what Ecodesign means for the stove industry and the environment alike. Since then, there has been a lot of focus on creating a cleaner, greener environment – with much focus being in London.
Only recently the Mayor of London called for additional powers to further limit pollution in the capital. Open fires, well know for being highly un-environmentally friendly, have come under much criticism as part of this environmental clean up. While the Ecodesign Ready initiative, by contrast is a clear ally in the pursuit a cleaner environment.
How an Ecodesign Stove is so Environmentally Friendly:
The main drive of the 2022 Ecodesign rules for wood burning stoves, is to significantly reduce unwanted emissions from the combustion of wood in domestic stove fireboxes, whilst maintaining a good thermal efficiency.
It is hard for the stove development engineer to achieve these new clean burning levels, but what exactly is needed within a firebox to produce cleaner emissions?
Here is an insight into some of the things a stove development engineer pays specific attention to, in making an ecodesign ready stove:
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- Gasification: A solid log does not just burn by itself, it needs to be broken down into constituent parts by thermally degrading it into gases and solid matter. The solid elements act like a sort of wick in a candle, and all the gases produced burn as bright attractive flames above the fuel within the firebox. To achieve this thermal breakdown it is important to get the right burning conditions, especially the retention of heat within the fuel bed.
. - Secondary Air: This is usually present in modern wood burners, primarily for the objective of maintaining clean glass as an air wash, but secondary air is an important part of burning off the gases produced by logs within the combustion chamber. In fact a portion of the secondary air can act as primary air, as well in promoting the gassing off from the solid logs during the burn cycle.
. - Tertiary Air: This is probably the development that has most reduced smoke emissions over recent years, and is in fact extra secondary combustion air by a different route. The entry points are usually above the fuel in the rear of the firebox and continue combustion flames once the majority of primary and secondary air have done their job.
. - Mixing Fuel & Air: This is often overlooked but it is critical to mix the fuel and air well inside the firebox. Air that pays no part in the combustion process just cools the firebox, and carries away heat into the flue, hence the poor thermal efficiency of an open fire. The entries for the various air injection stages, plus the shape of the firebox itself contribute to the mixing and therefore completeness of combustion.
. - The Conditions Inside The Firebox: These are critical to the effects of all the foregoing stages. For example if heat is lost too quickly, then flames will stop burning before combustion is completed. Also no matter how hot they are, pockets of unburned gases with no oxygen present cannot burn any further.
In summary the only way to succeed at achieving Ecodesign levels of combustion is to get the various elements of the whole system to work as one, to truly maximise the combination of fuel gases and air. It is possible to use innovations in this process such as C&J’s own patented tertiary air profiling system, used within Purevision stoves, which optimise the mixing of tertiary air into the gases above the fuel bed.
One thing we can be certain of, is that there will be continued pressure to improve the combustion process within wood burners to reduce unwanted emissions or particulates and gaseous carbon compounds. Here at Charlton & Jenrick we intend to stay at the forefront of those developments.
