Air intake for this type of biochar burner

Share this post

Share on facebook
Share on linkedin
Share on twitter
Share on email

I cut three square holes like this and when we burnt it was finished in 3.5 hrs but nothing was charred?

The char in the picture was from the first burn that was 2o hrs… All done.
Reply from Peter Hirst:
You need at least four of those holes, probably six, evenly spaced around the bottom of the outer barrel.  Then you need secondary air holes, smaller but more of them, evenly spaced around the top.  .  The inner barrel has to be completely sealed, except where gas is allowed to escape under the bottom rim  and the space between inner and outer barrel  packed with small fuel, lit at the top before the lid and chimney are placed.

PEter
previously I had written him that we had successful char in a much longer period without these extra air vents. We only had 2 slits made with a grinder on each side. This gave the effect of a 20 hr space heater (IE.,in greenhouse). I don’t see that making more holes will increase the charring in the inside barrel. So we will block up the holes and continue with the 20 hr burner. I think this will be more useful than obtaining a quick char.

Further reading

100 years later… Farming Today

Some of the principles that Howard wrote about 100 years ago are just being talked about in this broadcast of Farming Today. From the Groundswell

Support Our Projects

Whilst Good Gardeners International is lucky enough to generate some income through our own products, we still rely heavily on invaluable donations from people such as yourself. If you can support us and the work we do, there are four options below to get involved.