{"openapi":"3.1.0","info":{"title":"Chimney & Flue API","version":"1.0.0","description":"Chimney and flue sizing maths as an API, computed locally and deterministically — the draft and dimension numbers a stove installer, sweep or builder runs so a fire pulls cleanly and safely. The flue-size endpoint gives the minimum flue cross-section for a fireplace opening: at least a tenth of the opening area for a square or rectangular liner, a twelfth for a round one (which draws better) — a 36 × 30 inch opening needs about 108 square inches of rectangular flue, or a 10.7-inch round. The draft endpoint gives the theoretical draft from the stack effect, ΔP ≈ 3465 × height × (1/T_outside − 1/T_flue) with temperatures in kelvin, so a 6-metre chimney with 200 °C flue gas on a freezing day pulls about 32 pascals (0.13 inches of water column) — taller and hotter draws harder. The height endpoint applies the 3-2-10 rule: a chimney must finish at least 3 feet above where it pierces the roof and at least 2 feet above anything within 10 feet, whichever is higher. Everything is computed locally and deterministically, so it is instant and private. Ideal for hearth and stove-installer apps, chimney-sweep and inspection tools, building-design calculators, and DIY-safety sites. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. Educational estimates — verify against your appliance listing and adopted code.","contact":{"name":"PremiumApi","url":"https://www.oanor.com/by/premiumapi"}},"servers":[{"url":"https://api.oanor.com/chimney-api","description":"oanor gateway"}],"tags":[{"name":"Chimney"},{"name":"Meta"}],"components":{"securitySchemes":{"oanorKey":{"type":"apiKey","in":"header","name":"x-oanor-key","description":"Get your key at https://www.oanor.com/developer/keys"}}},"security":[{"oanorKey":[]}],"paths":{"/v1/draft":{"get":{"operationId":"get_v1_draft","tags":["Chimney"],"summary":"Theoretical stack-effect draft","description":"","parameters":[{"name":"height_m","in":"query","required":true,"description":"Chimney height in metres","schema":{"type":"string"},"example":"6"},{"name":"flue_temp_c","in":"query","required":true,"description":"Flue gas temperature °C","schema":{"type":"string"},"example":"200"},{"name":"outside_temp_c","in":"query","required":true,"description":"Outside air temperature °C","schema":{"type":"string"},"example":"0"}],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK","content":{"application/json":{"example":{"data":{"note":"Theoretical draft ≈ 3465 × height × (1/T_outside − 1/T_flue), with temperatures in kelvin — taller chimneys and hotter flue gas pull harder, and a cold outside boosts it. Real draft is lower after friction and bends. Most appliances want roughly 10–30 Pa (0.04–0.12 in w.c.); too much draft wastes heat up the flue.","inputs":{"height_m":6,"flue_temp_c":200,"outside_temp_c":0},"draft_pa":32.2,"draft_in_wc":0.1292},"meta":{"timestamp":"2026-06-06T15:30:41.880Z","request_id":"21f1b41c-e3b4-4c79-9b3e-74dd185615e4"},"status":"ok","message":"Draft","success":true}}}},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}},"/v1/flue-size":{"get":{"operationId":"get_v1_flue_size","tags":["Chimney"],"summary":"Minimum flue size for an opening","description":"","parameters":[{"name":"opening_width_in","in":"query","required":true,"description":"Fireplace opening width in inches","schema":{"type":"string"},"example":"36"},{"name":"opening_height_in","in":"query","required":true,"description":"Fireplace opening height in inches","schema":{"type":"string"},"example":"30"}],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK","content":{"application/json":{"example":{"data":{"note":"A fireplace flue should be at least 1/10 of the fireplace opening area for a rectangular/square liner, or 1/12 for a round one (round draws better). Too small and smoke spills into the room; far too large and the flue gases cool and the draft stalls. Match a stove's flue to its collar, not the room.","inputs":{"opening_width_in":36,"opening_height_in":30},"opening_area_sqin":1080,"min_rect_flue_area_sqin":108,"min_round_flue_area_sqin":90,"min_round_flue_diameter_in":10.7},"meta":{"timestamp":"2026-06-06T15:30:41.957Z","request_id":"73bffebd-741f-49b8-8e7e-c51652fd788b"},"status":"ok","message":"Flue size","success":true}}}},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}},"/v1/height":{"get":{"operationId":"get_v1_height","tags":["Chimney"],"summary":"3-2-10 minimum height","description":"","parameters":[{"name":"penetration_height_ft","in":"query","required":true,"description":"Roof-penetration elevation in feet","schema":{"type":"string"},"example":"20"},{"name":"tallest_within_10ft_ft","in":"query","required":false,"description":"Tallest roof/structure within 10 ft (default 0)","schema":{"type":"string"},"example":"24"}],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK","content":{"application/json":{"example":{"data":{"note":"The 3-2-10 rule: a chimney must terminate at least 3 ft above where it passes through the roof AND at least 2 ft above any roofline or structure within 10 ft horizontally — whichever is higher governs. A short chimney near a tall ridge drafts poorly and backs up; when in doubt, go taller.","inputs":{"penetration_height_ft":20,"tallest_within_10ft_ft":24},"governing_rule":"2 ft above obstruction within 10 ft","required_top_elevation_ft":26,"min_height_above_penetration_ft":6},"meta":{"timestamp":"2026-06-06T15:30:42.029Z","request_id":"b54e6d17-a1a4-48cb-9f09-4219ecb34109"},"status":"ok","message":"Height rule","success":true}}}},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}},"/v1/meta":{"get":{"operationId":"get_v1_meta","tags":["Meta"],"summary":"Spec","description":"","parameters":[],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK","content":{"application/json":{"example":{"data":{"notes":"Flue ≥ 1/10 of opening (1/12 round); draft = 3465·h·(1/To−1/Ti) in kelvin; 3-2-10 height rule. Educational estimates — verify against your fuel/appliance listing and adopted code.","service":"chimney-api","endpoints":{"GET /v1/meta":"This document.","GET /v1/draft":"Theoretical draft (Pa and in w.c.) from height and temperatures.","GET /v1/height":"Minimum chimney top height by the 3-2-10 rule.","GET /v1/flue-size":"Minimum flue cross-section for a fireplace opening (1/10 or 1/12)."},"description":"Chimney & flue maths: minimum flue size for a fireplace opening, theoretical stack-effect draft, and the 3-2-10 minimum-height rule."},"meta":{"timestamp":"2026-06-06T15:30:42.112Z","request_id":"c010f374-79fc-412b-b976-3e02a47c91bd"},"status":"ok","message":"Meta","success":true}}}},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}}},"x-oanor-pricing":[{"slug":"free","name":"Free","price_cents_month":0,"monthly_call_quota":420,"rps_limit":2,"hard_limit":true},{"slug":"starter","name":"Starter","price_cents_month":525,"monthly_call_quota":11000,"rps_limit":6,"hard_limit":true},{"slug":"pro","name":"Pro","price_cents_month":1720,"monthly_call_quota":72000,"rps_limit":15,"hard_limit":true},{"slug":"mega","name":"Mega","price_cents_month":5160,"monthly_call_quota":245000,"rps_limit":36,"hard_limit":true}],"x-oanor-marketplace-url":"https://www.oanor.com/api/chimney-api"}