Hydronic piping systems must be tested hydrostatically at one and one-half times the maximum design pressure, but not less than what psi?

Hydronic piping systems are crucial in heating and cooling applications, and testing these systems is essential to ensure their integrity and safety. According to the International Mechanical Code (IMC), these systems must indeed undergo hydrostatic testing at a pressure of one and one-half times their maximum design pressure. However, the code also establishes a minimum pressure requirement that must be adhered to during testing.

In this case, the minimum pressure specified for hydrostatic testing is set at 100 psi. This standard serves as a safeguard to ensure that even at lower design pressures, the integrity of the piping system is verified. By establishing this minimum, the code helps to prevent potential failures and ensure that the system can withstand pressures that may exceed typical operating conditions, thereby promoting safety and reliability in hydronic systems.

The other choices provided are not the minimum required value, and selecting any of those would not align with the requirements set forth in the IMC, thus failing to fulfill the necessary testing criterion for hydrostatic pressure testing in hydronic systems.