Please explain BURN CYCLES

[jadm]

I read about burn cycles in individual topics posted here but have not found where an article is that goes in to detail about them.

Can someone fill me in on the specifics of each cycle and how they are identified?

I'd also like to know how to work with them in regards to how I burn wood in my insert. I've figured a bit out through trial and error but I am sure there must be a more efficient/scientific way of doing what I'm trying to achieve here (Getting the most out of my fuel with the least amount of waste).

Thanks!

 

[webbie]

Basics....although I'm certain others can do better!

First phase is the wood heating up and losing it's moisture.
Second phase is the wood gases (smoke) coming off the wood - ideally these gases are burnt and that is that makes the dance of secondary combustion in non-cats and what fuels cats.

The third phase is when the gases have all been released and the wood is reduced to hot embers (carbon). In this stage it is more like coal and tend to put out very little smoke.

In general, the first phase wants to have a lot of air, the second phase a medium amount and the third phase can exist with very little air. Of course, in the real world some of these phases are all happening at the same time, etc.

See:
http://www.canren.gc.ca/prod_serv/index.asp?CaId=103&PgId=613

 

[jadm]

Thanks for the definition. Easy to understand!

 

[Heat Miser]

To add to the excellent explanation given above:

You don't want to add wood to your stove until you reach the stage where all you have left are coals. My first year of burning I was constantly adding wood every couple hours trying to keep an even temperature/burn. I realized quickly that I was consuming a lot more wood, the house was too hot, and it was a lot of work.

Now after doing this for a few years I only open up the top loader to add wood when I have hot coals remaining and I don't see any obvious big pieces of unburned splits. The hot coals are good enough to quickly ignite the wood with little smoke and the burn cycle is a lot longer (8-10 hours normally). I only load the stove three times a day: Morning, Early Evening and before bed. The stove burns a lot more efficiently and I'm using a heck of a lot less wood it seems.

 

[bokehman]

You don't want to add wood to your stove until you reach the stage where all you have left are coals.

In the Jotul C31/33 manual it says the opposite. Something along the lines of: Add two splits (length: 50cm/20", diameter: 8-12cm/3-5", combined total weight: 1.8kilos/4lb) every 50 minutes. But it also says burn to embers before reloading.

 

[Heat Miser]

You don't want to add wood to your stove until you reach the stage where all you have left are coals.

In the Jotul C31/33 manual it says the opposite. Something along the lines of: Add two splits (length: 50cm/20", diameter: 8-12cm/3-5", combined total weight: 1.8kilos/4lb) every 50 minutes. But it also says burn to embers before reloading.

I run a VC Defiant catalytic so perhaps the operations are different. But other literature I've read also agrees with reloading on hot coals as part of the cycle. Reloading every 50 minutes does not seem like practical advice for most people. I'd say try both to see what works better for the stove.

 

[stoveguy2esw]

adding wood during the second stage is going to rob efficiency , the new wood will enter its char stage which will add moisture to the smoke released , this retards the secondary combustion in a cat (or reburn type non-cat) a percentage of the energy you want to convert to heat from the secondary stage (which is the most productive stage) is instead appropriated to char the new wood. more combustion air is often needed in the char stage and users invariably open the draft to get the new wood burning rapidly , this will char more quickly , but in doing so it allows the remaining secondary energy to escape up the flue. as craig stated above , the most effective way to squeeze the best output from each stick of wood is to load, char, burn to coals , rake and repeat, adding wood in the middle of the cycle is a less effective way to operate most any stove.