The Snawfus Hearth

A 20–30 minute hot batch fire, twice a day, radiates steady heat for 18–24 hours off the mass — the same principle as a true Russian stove, achieved through two stacked bells instead of a channel maze. The lower bell captures direct combustion heat; the upper bell cools the gas further and houses the bake oven and hot water coil, fed by a bypass damper that routes hot gas under the oven floor during the burn.

Tier Ladder

• Settler — Hearth Starter: small single-bell-pair unit, no oven, ~1,500–2,000 lb mass, sized for 400–700 sq ft.
• Homesteader — Hearth & Oven: adds a front-loading bake oven off the upper bell, ~3,000–3,500 lb mass.
• Foreman — Full Hearth (Greenbrier spec): adds a heated bench and a copper coil thermosiphoning to a hot water tank, ~4,500–5,500 lb mass.
• Monticello — Great Hearth: whole-home scale, 7,000–9,000+ lb, dual flue liner, optional radiant floor tie-in.
• Mythic — The Snawfus Hearth: 10,000+ lb, twin-firebox option, cast iron cook surface, cast bronze fittings — the heater is the house's core.

Technical Specifications (Foreman tier baseline)

• Firebox: refractory core, batch-burn, ~1.5–2 cu ft, secondary air injection
• Bell system: double bell (lower/upper), Chernov-style, no serpentine channels
• Hot water coil: copper, sited in the upper bell, thermosiphon (no pump) to insulated storage
• Footing: isolated geopolymer pillar footing, independent of the surrounding slab
• Efficiency target: 85–90%+

Construction Variant: Quick RMH Prototype (Pre-Settler)

A genuinely different build tradition, not a smaller version of the double-bell design above — a J-tube rocket mass heater (fuel magazine + burn tunnel feeding an insulated vertical heat riser, topped with an exposed steel barrel as a fast-radiant surface, ducted through a sand or cob thermal-mass bench) instead of the Chernov-style double bell. Confirmed real, buildable, and cheap: a materials list built around a 6" well-casing steel pipe heat riser, perlite insulation, and firebrick only where the burn tunnel and riser actually need it, ran a scrounged-materials build for roughly $150. Meant as a fast, low-stakes proof-of-concept for the "burn hot, store heat in mass" principle before committing budget to a Foreman-tier double-bell build — not a replacement for it, and not to be merged into the double-bell spec above.

• Sizing rule: no component's cross-sectional area should exceed the flue's; the burn tunnel is the smallest CSA in the system, riser height scales with system CSA.
• Firebrick required in the burn tunnel and riser (high-heat zones); standard brick is fine elsewhere (e.g. around the ash box).
• Clearance: the exposed barrel/riser cap is a genuine burn hazard — reaches several hundred °F on the surface. Needs a locked clearance or physical barrier spec before building around young kids, not just "use thick metal."
• Not currently recognized under standard mechanical/building code the way an EPA-certified wood stove is — needs a WV-specific permitting check before this goes in as a buildable plan.
• Do not cite "8x more efficient than a standard stove" — real efficiency gain, but that specific multiplier is an unverified anecdotal figure with no instrumented test behind it.

Specialist Sign-Offs Required Before Construction

• Masonry heater specialist — bell sizing, flue draft calculation, dual liner clearances at Monticello+ tiers
• Structural engineer — point load at footing, especially for elevated installations
• Local code/chimney sweep certification — solid fuel appliance inspection, clearance-to-combustibles verification (RMH prototype needs its own check — see variant above)

Open Items

• Bench length/orientation not yet fixed — waiting on final floor plan
• Twin-firebox zoning logic for Mythic tier (redundancy vs. simultaneous dual-zone heating) needs a build-sheet pass
• RMH prototype: kid-safe clearance/barrier spec and WV code check still open — see kb-build/drafts/mm-pin-vetting-kb.json (pin_003_rocket_mass_heater, pin_014_rmh_steel_sand_build)