Insulated hot composter

A sealed, insulated bin with an air core down the middle. Hot compost from kitchen scraps and leaves in a few square feet, and it keeps going after an open heap has frozen.

No. 01

What happened here

I loaded it in mid-August 2026 with shredded leaves, cardboard tubes, dried food-recycler output and diluted urine. It reached 130°F within five days and held there for about a week, then eased to 120°F and down to 80°F over the next two weeks.

That drop looks like a stall from outside. It isn’t — it is the normal end of a hot phase. Turned and recharged with fresh nitrogen, it was back at 125°F in a single day, against five days from cold, because the microbes were already there and only hungry.

What to expect

Check it weekly, not daily. When the temperature drops, ask about moisture and compaction before you assume something is wrong.
The second hot cycle is shorter than the first.
It takes no woody material — that goes to the biochar instead.
The air core cuts down on turning. It doesn’t remove it.

Why insulated

This far north, an open heap stops working around November. The insulation is meant to carry it into December. This is the bin’s first winter here, and I will report how far it gets.

From the yard log

August 2026 Worked

Loaded in mid-August with shredded leaves, cardboard cores, food-recycler output and diluted urine. It reached 130 °F within five days and held there about a week, then settled at 120 °F. A day after reloading it was back up to 125 °F.

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