Efficient Coal Chulha for Heating

I’m developing a coal-fired chulha whose principal job is heating spaces, and I want it to work just as well in the living room on a chilly night as it does on an open veranda. The core requirement is long-lasting heat; I’d like the embers to hold temperature for hours with minimal refuelling so users can relax instead of constantly tending the fire.

Because the unit will serve both indoor and outdoor settings, good airflow control, smoke management, and safety shielding are essential. If your experience tells you that Portability or High efficiency upgrades can be incorporated without compromising the heat-holding goal, let’s explore them, but the emphasis must remain on sustained warmth.

Here’s what I need from you:
• A practical design (drawings or 3-D model) that can be fabricated with readily available materials
• A clear bill of materials and step-by-step build instructions
• Guidance on safe indoor operation, including ventilation and ash disposal recommendations
• An estimated burn-time profile and any simple tests I can run to verify performance

If you have worked on traditional stoves, biomass heaters, or similar combustion projects, please share examples so I can quickly understand your approach. I’m ready to move forward as soon as I see a concept that convincingly solves the long-lasting heat challenge.