My log burner is a Pönttöuuni RMH batch box with waterback that has no grate or under air, the fire burns flat on firebricks. I burn about 1 to 1.5 buckets per day. I usually burn 1 batch log stuffed firebox morning and evening, mid day when it is real cold.
I clean the firebox between each firing to harvest the char. It is then sifted to separate the ash, crushed in a low speed chipper and fed into the basement rotating vermicomposter.
With this procedure I get a warm home and hot showers from the char flair and about 1m3 of rich biochar vermicompost every winter for my garden.
During the winter I use this charpost in trays with professional LED grow lamps in a ladybug infested mylar tent to grow fresh herbs and salad all winter long. The maths show my salad doing this is about 5x cheaper than the store accounting for the lamps, with flavor and nutrients no store sells.
Come spring I tip out the trays into my hugel raised garden beds making a very instant summer garden for our short growing season.
The sifted ash fraction is mixed into the garden watering jugs periodically over the summer to water in phosphorus, calcium, and it's other minerals to boost my fruit production and prevent blossom end rot.
