Fixtures, Fixture Fittings, and Water Heaters
Fixture Requirements
This domain covers fixture materials, installation clearances, accessibility, and water efficiency. Know that fixtures must be of an approved material, properly supported, and installed with the required clearances and trap seal protection. Water closets, lavatories, sinks, and floor drains each have specific installation rules. Accessibility standards (reach ranges, clear floor space) appear in questions about public facilities.
Water Heaters
Water heater questions test temperature-and-pressure relief valve requirements, discharge piping, thermal expansion, combustion air, and venting. Know that the T&P relief valve must be rated for the heater, piped full size to a safe discharge, and not threaded or capped at the end. Gas water heaters require combustion air and proper venting; electric heaters require safe wiring and disconnect.
Traps
- Assuming any relief valve works; it must match the heater's rating.
- Forgetting that discharge piping cannot be reduced or trapped.
- Overlooking thermal expansion in closed systems.
- Confusing fixture clearances with accessibility clearances.
- Ignoring that a floor drain needs a trap primer where required.
Worked Example / Rule of Thumb
When reviewing a water heater installation, check four items: T&P valve present and rated, discharge full size and safe, combustion air adequate (gas), and venting correct. Rule of thumb: if the discharge ends where someone could be scalded or where it can be capped, it fails.
Fixture traps must maintain their seal; trap primers protect infrequently used floor drains.