High pressure, the PRV, and the expansion tank

Over 80 psi, a PRV is required to reduce it (IPC 604.8) — and because that closes the system, a thermal-expansion tank is required too (IPC 607.3).

Diagram of a home water service showing pressure control. The street can deliver over 100 psi; where static pressure exceeds 80 psi, a pressure-reducing valve (PRV) is required to bring it down to about 60 psi (IPC 604.8). Adding the PRV closes the system, so IPC 607.3 then requires a thermal-expansion tank on the water heater’s cold supply so heating cycles don’t spike the pressure. — Source: IPC 604.8 & 607.3

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Diagram of a home water service showing pressure control. The street can deliver over 100 psi; where static pressure exceeds 80 psi, a pressure-reducing valve (PRV) is required to bring it down to about 60 psi (IPC 604.8). Adding the PRV closes the system, so IPC 607.3 then requires a thermal-expansion tank on the water heater’s cold supply so heating cycles don’t spike the pressure.

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