On the 175,000 BTU reznor unit heaters 3H917NA, what is the gas line psi requirement?

Hello, thank you for reaching out. The gas supply pressure must not exceed 1/2 psi (14 inches water column) at the unit's gas valve. If you have additional questions, please feel free to reach out over the phone to our Customer Service line at 1-888-901-5460. Have a great rest of your day.