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TERMINAL
BLOCK
TO UNIT
TERMINAL
CONTROL
BLOCK
CIRCUIT
C
W
24V CIRCUIT
ENERGY RECOVERY VENTILATOR CONTROL
The 62XC,XD units can be equipped with an optional enthalpy
type Energy Recovery Ventilator (ERV). ERV operation is en-
abled whenever the unit is in occupied mode. See the Operation
section of this manual for ERV operating sequence.
VFD Defrost
The ERV may be equipped with a VFD for frost control. The VFD
will slow the rotating speed (45 RPM) to the configured minimum
speed (10 RPM) when the temperature of the return air coming off
the wheel (WExAT) is equal to or less than 25°F (configurable in
the VFD controller). Slowing the wheel with inhibit the formation
of frost. Refer to the VFD section for additional information on
the VFD.
NOTE: The variable speed defrost control slows down the speed
of the wheel to reduce its effectiveness and keeping the return air
from getting fully saturated which can lead in condensation of the
wheel and possible frosting.
The 25°F default setpoint does not cover the whole range of appli-
cations where frosting may occur. Under certain conditions (high
R.H. % from the return air and very low OA DB temperatures)
frosting may occur even below the default setpoint.
This setpoint MUST be adjusted to ensure that the return air when
cooled down by the ERV does not reach its dew point temperature.
–
+
0-10
VDC
INPUT
SEE MANUAL FOR
SIGNAL
INPUT SIGNAL
WIRING
3 2 1
SCR CONTROLLER
YELLOW
Fig. 98 — SCR Control Electric Heat
LIMIT
SWITCH
TRANSFORMER
GROUND
The Heat source must be sized accordingly to account for reduc-
tion in capacity for applications where the unit will enter in defrost
mode.
ERV Maintenance
BEARINGS
All units will be equipped with permanently lubricated inboard
bearings. These bearings should require no maintenance for the life
of the equipment. If the ERV is equipped with external flanged
bearings, lubricate annually with a petroleum based lubricant.
ERV MOTOR
Verify motor alignment and electrical connections.
BELT
Check motor alignment, belt tension and wear. Replace belt as re-
quired.
VFD
Check electrical connections, tighten as required.
BYPASS
Check operation for binding, lubricate as required. Check actuator
electrical connections.
FILTERS
Replace as required.
65
AIR PRESSURE
SWITCH
MANUAL
RESET
LIMIT
HEATER
RELAY
TERMINAL
BLOCK
MAIN
TERMINAL
BLOCK
L1
L2
L3
3 PHASE
60 CPS
SUPPLY
POWER TO
FAN MOTOR
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