Valent Controls IOM 66 IOM-C1-0616
Part Number 474626
E. Enable the final fixed stage of capacity and modulate the Digital Scroll™ to maintain the evaporator coil leaving
air temperature setpoint (310 and 350 casings only).
6.3. [Active Head Pressure Control 1.0] To maintain a consistent condensing temperature in cooling and dehumidification
mode, the controller shall perform functions.
A. Enable and modulate single bank of condensing fans with a variable frequency drive to maintain a condensing
temperature of 110°F.
B. As head pressure rises, a mechanical switch shall enable additional condensing fans and first bank of
condensing fans shall modulate to maintain a condensing temperature of 110°F.
C. As head pressure lowers, individual condensing fans shall disable condensing fans first bank of condensing
fans shall modulate to maintain a condensing temperature of 110°F.
6.4. [Active Head Pressure Control 2.0] To maintain a consistent condensing temperature in cooling and dehumidification
mode, the controller shall perform functions.
A. Enable and modulate all condensing fans with EC motors at the same speed to maintain a condensing
temperature of 110°F.
7. COOLING & REFRIGERATION – WATER SOURCE HEAT PUMP
7.1. In cooling mode the controller shall perform the following functions.
A. Enable the Digital Scroll™ compressor and modulate capacity to maintain supply air temperature setpoint.
B. If the Digital Scroll™ compressor is not able to maintain the supply air temperature, additional fixed stages of
capacity shall be enabled and the Digital Scroll™ shall continue to modulate to maintain the supply air
temperature setpoint.
C. If the combination of multiple compressors provides lowers the supply air temperature below its setpoint, the
controller shall disable one or more fixed stages of capacity.
7.2. In dehumidification mode the controller shall perform the following functions.
A. Enable a fixed stage of capacity to maintain or exceed the evaporator coil leaving air temperature setpoint.
B. Modulate the hot gas reheat valve to maintain the supply air temperature setpoint.
C. Enable the Digital Scroll™ compressor to maintain the evaporator coil leaving air temperature setpoint.
7.3. To maintain a consistent condensing temperature in cooling and dehumidification mode the controller shall modulate
the water valve on each circuit to maintain a condensing temperature of 110°F.
8. HEATING – INDIRECT GAS FURNACE
8.1. In heating mode the unit controller shall perform the following actions.
A. Enable indirect gas furnace.
B. Modulate capacity to maintain the supply air temperature setpoint.
8.2. When an enable signal is received from the unit controller, the furnace controller shall initiate the following ignition
sequence.
A. Enable the combustion blower at full speed for 15 seconds on 110/210/310 casings and 30 seconds on 350
casings.
B. Modulate the gas valve to 100% on 110/210/310 casings and 55% on 350 casing furnace.
C. Enable the spark igniter for 10 seconds on 110/210/310 casings and 5 seconds on 350 casings.
D. Hold the ignition modulation setpoint for 30 seconds on 110/210/310 casings and 120 seconds for 350 casings.
8.3. Once the ignition sequence is complete, the furnace controller shall perform the following actions.
A. Modulate the gas valve based on the modulation signal from the unit controller.
B. Lower and raise the speed of the combustion fan based on the modulation signal from the unit controller (two-
speed).
8.4. If the furnace controller does not receive confirmation of a successful ignition sequence (flame providing switch not
made), it shall initiate the ignition sequence two additional times on 110/210/310 casings and three additional times
on 350 casings.
8.5. Upon the loss of the enable signal from the unit controller, the furnace controller shall perform the following actions.
A. Modulate the gas valve to 0%.
B. Increase the combustion blower to full speed for 30 seconds on 110/210/310 casings and 60 seconds for 350
casings.
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