A check valve traps heated water between the service and tank. Which pressure condition needs control?
- AFixture-unit diversity
- Expansion pressure from heating the trapped water
- CLoss of drainage venting
- DReduced gas heating value for the described plumbing system and documented site conditions
Why B is correct
The best answer is: Expansion pressure from heating the trapped water. Heated water expands. In a closed distribution system that volume cannot return toward the source, so an approved and properly sized expansion-control method prevents pressure rise and nuisance relief discharge. The transferred field condition applies the same plumbing design, installation, service, or safety principle to a different project setting. The alternatives omit a prerequisite, conflict with the approved method, or fail to control the stated sanitation or physical hazard.