Specifications
VCES-ERV-IOM-1A – ERV500i/e
24
Wheel Rotation Sensor
ERVs can be equipped with a wheel rotation sensor op-
tion. This option cannot be ordered for a non-defrost unit.
This option cannot be used in conjunction with a digital
wall control and must be ordered with a control board.
With the wheel rotating, the wheel rotation sensor board
activates the relay coil and closes the ‘NO’ (normally open)
set of contacts across the occupied/timer sensor contacts
(pin 3 and 4), allowing the unit to operate. If the wheel
rotation stops (unless in an enthalpy state, defrost mode
or unoccupied condition), the contacts will be open and
cause the motors to shut down and the dampers (op-
tional) to close.
A set of 24 VAC wheel alarm contacts are available on the
terminals to power a light or indicator. The drawing below
shows the wiring necessary to power the 24 VAC light or
indicator.
CO
2
Ventilation Control
ERVs can be controlled by a CO
2
controller that can be
connected to fan control Low-Com-High (not all units
have two speeds). As the CO
2
levels exceed acceptable
limits, the dry contact across High-Com is closed, raising
high speed fan ventilation.
IMPORTANT
If the wheel rotation sensor board shuts the unit down,
the only procedure to re-start the unit is to turn the
power off and then back on again.
CAUTION
The wheel rotation sensor printed circuit board has 120
VAC wired to two terminals. Improper wiring or handling
of the circuit board could either damage the board, the
unit or cause personal injury.
LED 1 2 3
NO COM NC 24V COM VENSEN ALA DIS
NO COM NC
24 COM SEN
DEF+ DEF−
CAUTION
120 VAC
DEF+ DEF-
CAUTION
120 VAC
VEN ALA DIS
NO = NORMALLY OPEN
NC = NORMALLY CLOSED
COM = COMMON
24V = 24 VAC
COM = COMMON
SEN = SENSOR
ALA = RELAY ON (24 VAC LIGHT, MAX. 1 AMP)
DIS = ROTATION DETECTOR DISABLE (24 VAC)
VEN = VENTILATION MODE (DISABLE WRS) (24 VAC)
DEF+ = DEFROST MODE (DISABLE WRS) (120 VAC)
DEF- = DEFROST MODE (DISABLE WRS) (120 VAC)
NO NC
RELAY
COM SEN
COM
SENSOR
MAGNET
J1 J2
DELAY
J1 J2
DELAY
LED 1 2 3
J1 & J2 = DETECTION DELAY
J1 J2 DELAY
1 min.
X 2 min.
X 4 min.
X X 8 min.
*default
1 = RELAY ON (RED)
2 = POWER ON (GREEN)
3 = SENSOR DETECTION INDICATOR (YELLOW)
*
Figure G7: Wheel rotation sensor board
24 VAC LIGHT or INDICATOR
(supplied by others)
WRS BOARD RELAY
'NC' CONTACTS
(normally closed –
opens on wheel failure)
CONTROL CONTACTS
CLASS 2 VOLTAGE
WALL CONTROL
BLACK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
NOTE:
Connections are all dry contacts
except wall control, wheel alarm
contacts and 24 VAC power contacts.
Use of 24 VAC circuit requires
isolating contacts (ex. thermostat)
to prevent interconnection of
Class 2 outputs.
RED
OCCUPIED
TIMER/
SENSOR
FIELD WIRED
TERMINALS
AB
UNOCC.
RECIRC
CONTACTS
LOW
COMMON
HIGH
DIRTY
FILTER
INDICATOR
(1.5A–24 VAC)
(ERV UNITS)
WHEEL
ALARM
OPTION
(24 VAC)
(ERV UNITS)
ENTHALPY
(−) 24 VAC
(40 VA)
(+) 24 VAC
GREEN
YELLOW
(RECIRC UNITS)
Figure G8: Wheel rotation alarm
FACTORY MOUNTED
JUMPER
CO
2
SENSOR
AC INPUT
AC GROUND
NC NO
CONTROL CONTACTS
CLASS 2 VOLTAGE
WALL CONTROL
BLACK
1
2
3
4
5
6
7
8
9
10
11
8
12
13
14
15
16
17
18
19
20
NOTE:
Connections are all dry contacts
except wall control, wheel alarm
contacts and 24 VAC power contacts.
Use of 24 VAC circuit requires
isolating contacts (ex. thermostat)
to prevent interconnection of
Class 2 outputs.
Note 1: Terminal 5 on CO
2
sensor
used only with two-speed units.
Note 2: Terminal 7 and 8 on CO
2
sensor used only with blower VFDs.
NORMAL OPERATION – LOW SPEED
CO
2
LEVELS EXCEED SETPOINT – HIGH SPEED
RED
OCCUPIED
TIMER/
SENSOR
FIELD WIRED
TERMINALS
AB
UNOCC.
RECIRC
CONTACTS
LOW
COMMON
HIGH
DIRTY
FILTER
INDICATOR
(1.5A–24 VAC)
(ERV UNITS)
WHEEL
ALARM
OPTION
(24 VAC)
(ERV UNITS)
ENTHALPY
(−) 24 VAC
(40 VA)
(+) 24 VAC
GREEN
YELLOW
(RECIRC UNITS)
7
6
5
3
2
1
2
1
4
Figure G9: CO
2
ventilation control