@MindfulWilliam Huh. I like the idea of capturing the heat from a pile! I hadn't thought of that. Mind you, I don't have a use for it... no chickens, no greenhouse, and the wife would never allow the messiness of a working pile. But I do compost. Here is my solution. I built it out of hemlock (rot resistant). Two active chambers, alternated when filled. Sawdust from the wood pile and fire place ash for carbon and kitchen scraps and cuttings for nitrogen.