E 503.4.6.3 Off-Hour Controls
- Controls that can start and stop the system under different time schedules for seven different day-types per week, are capable of retaining programming and time setting during loss of power for a period of not less than 10 hours, and include an accessible manual override, or equivalent function, that allows temporary operation of the system for up to 2 hours.
- An occupant sensor that is capable of shutting the system off where no occupant is sensed for a period of up to 30 minutes.
- A manually operated timer capable of being adjusted to operate the system for up to 2 hours.
- An interlock to a security system that shuts the system off where the security system is activated.
Exception: Residential occupancies shall be permitted to use controls that can start and stop the system under two different time schedules per week. [ASHRAE 90.1:22.214.171.124.1]
Exception: Radiant heating systems capable of and configured with a setback heating setpoint at not less than 4°F (2°C) below the occupied heating setpoint. [ASHRAE 90.1:126.96.36.199.2]
Exceptions: Isolation devices and controls are not required for the following:
- Exhaust air and outdoor air connections to isolation zones where the fan system to which they connect is not more than 5000 ft3/min (2.3597 m3/s).
- Exhaust airflow from a single isolation zone of less than 10 percent of the design airflow of the exhaust system to which it connects.
- Zones intended to operate continuously or intended to be inoperative only when all other zones are inoperative. [ASHRAE 90.1:188.8.131.52.4]