Select Proportional Output if the coil is controlled by a proportional valve that takes a 0–10 VDC or 4–20 mA signal. Selecting this option provides additional options to control Two Valves if you have a one third, two thirds valve arrangement. If you do not select the two valves option, you can add a Face and Bypass Damper to allow some air to bypass the coil in certain conditions. When the switchover temperature falls below the face and bypass damper switch over setpoint, the valve opens fully and the face and bypass damper modulates to maintain temperature. When the switchover temperature is above the face and bypass damper switchover setpoint, the damper opens fully to the coil and the valve modulates. The face and bypass damper can be controlled using a Proportional Actuator or an Incremental Actuator.
The option for Two Proportional Valves is intended for two sequenced steam valves. This option does not support including Face and Bypass Damper or Circulation Pump controls.