Design Blueprint: Cookstove Carbon Monoxide Witness and Chimney-Draft Flue

DESIGN BLUEPRINT — SIMULATED, NOT MEASURED — NOT BUILT. A build specification derived from the source paper (DOI 10.5281/zenodo.24108910): a US$19.80 (volume) electrochemical carbon monoxide witness that works as an alarm (11.7% relative uncertainty at 35 ppm) but cannot certify compliance with the WHO 24-hour guideline — zero drift limits its smallest resolvable exceedance to 2.3 times the guideline (8.0 ppm) — paired with a 0.15 m diameter, 3.5 m flue costing US$49.10 that delivers the 0.045 m3/s design flow for a 3.0 kW flue-connected fire in calm air and against a 5 m/s adverse wind, and fails at cold start, at low fire on a hot day, and against an 8 m/s adverse wind (0.0 m3/s). Includes bill of materials, sizing rules, assembly, installation, commissioning, maintenance, and failure modes. Sole author: William Alexander Aldred (ORCID 0009-0000-1215-577X). CC BY 4.0.