CSLB C-36 Plumbing ContractorFixture and Appliance InstallationMedium
A plumber is installing a solar water heater system. The local code requires a pressure relief valve (PRV) on the hot water storage tank and a temperature relief valve (TRV) or a combination T&P valve. What is the maximum allowed pressure setting for a PRV on a residential hot water storage tank, as per common plumbing codes like the UPC?
- A75 psi
- B125 psi
- C150 psi
- D100 psi
Show answer & explanationAnswer & explanation
Correct answer: C. 150 psi
Common plumbing codes, such as the Uniform Plumbing Code (UPC), typically specify that pressure relief valves (PRVs) on hot water storage tanks must be set to open at a maximum of 150 psi. This protects the tank from excessive pressure buildup.
Why the other options are wrong
- A. 75 psi is too low for a standard residential water heater PRV setting.
- B. 125 psi is closer but not the typical maximum for residential PRVs.
- D. 100 psi is also too low and would likely cause nuisance tripping.
Water Heater Pressure Relief Valve (PRV) Setting
The maximum pressure at which a pressure relief valve on a hot water storage tank is designed to open, releasing excess pressure to prevent tank rupture.
- Standard maximum setting is 150 psi.
- Acts as a critical safety device.
- Must be properly sized and installed according to code.
Memory trick: Pressure Relief: 'Protect Regularly' at 150 psi.