Valent Controls IOM 68 IOM-C1-0616
Part Number 474626
A. The controller shall enter the defrost mode when all of the following conditions are met.
a. Suction temperature is less than 30°F.
b. Suction temperature is equal to or greater than the outdoor air dewpoint less 25°F.
B. The controller shall perform the following functions in the defrost mode.
a. Outdoor air damper shall close.
b. Return air damper shall open (operates inversely of outdoor air damper).
c. Exhaust fan (if equipped) shall disable.
d. Condensing fans shall disable.
e. Energy recovery wheel (if equipped) shall disable.
f. Supply fan shall modulate to the maximum design speed.
g. Reversing valve shall enable to make indoor coil the evaporator and outdoor coil the condenser.
h. Compressor(s) shall enable and/or modulate to full capacity.
i. Mechanical heat source enabled to maintain supply air temperature setpoint.
C. The controller shall exit the defrost mode under the following conditions.
a. Condensing temperature reaches 60°F.
D. If the controller enables three defrost modes in one hour of operation, the controller shall disable the heat pump
and enable the mechanical form of heating.
13. MODULATION SEQUENCES
13.1. Supply Fan Modulation
A. The controller shall modulate the supply fan speed based on the following input.
a. Duct static pressure.
b. Space static pressure.
c. 0-10 VDC input (signal provided by others).
d. BAS communication.
13.2. Damper Modulation
A. The controller shall modulate the outdoor air and return air damper based on the following input.
a. Space static pressure.
b. Outdoor air volume.
c. Space carbon dioxide.
d. BAS communication.
13.3. Exhaust Fan Modulation
A. The controller shall modulate the exhaust fan speed based on the following input.
a. Space static pressure.
b. 0-10 VDC input (signal provided by others).
c. BAS communication.
d. Supply fan tracking.
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