About Physics of Buildings
Physics of Buildings explains how the systems inside homes and commercial buildings work, through their physics: pumps, tanks, drains, boilers, heat pumps, ducts and wires. It is written for two readers at once: the homeowner with a problem, and the technician, apprentice, student or engineer who wants the mechanism and the numbers.
This page on plumbing traps and vents is a Physics of Buildings explainer. It is made by an AI-assisted production system: an AI agent researched the sources, wrote the text, and built the simulations and the calculator, and a separate, independent verification step checks every claim and every model against the cited sources before the page is published. There are no ads and no sign-up.
How the physics is checked§
Every model behind a figure is tested twice: by its author against worked examples and limiting cases, and by an independent test suite written from the model specification and the sources alone, without reading the model’s code. Every factual claim is recorded in a claims register with its source and checked by a reviewer who did not write it. What each figure simplifies is stated next to it and collected on the sources page. The simulations use representative numbers (an illustrative flush, vent and wind) to show each mechanism; they are labelled as simulated.
Editorial boundaries§
- We explain mechanisms and help you describe a problem. A symptom list gives common causes, not a diagnosis; a licensed plumber confirms the cause.
- Vent, stack and drain work, roof access, and anything that opens the drainage system to the room are jobs for a licensed plumber. Sewer gas can be toxic and flammable.
- Plumbing codes (the International Plumbing Code, the Uniform Plumbing Code and local amendments) differ from place to place. We describe what codes require in general terms and do not reproduce code text. Nothing here is a statement of code compliance, and no figure or calculator result is a sizing method or a guarantee.
- Manufacturers’ documents are cited because they publish the numbers installers use; citing one is not an endorsement.
Found an error?§
Please open an issue on the source repository. Corrections are welcome and credited.
Reuse§
Text and figures are licensed CC BY 4.0; code is MIT. Teachers and trainers may use and adapt any of it, with attribution.