Specifications

VCES-ERV-IOM-1A – ERV500i/e
10
The unit functions are controlled by integrated unit con-
trols including recirculation/exhaust only defrost (optional).
In cold temperatures, frost control cycles will remove frost
from the enthalpy wheel to maintain proper operation.
This removal of frost occurs when a damper closes the
outside air port and allows room air to circulate through
the enthalpy wheel and back to the vented room. Each
unit has different frost control requirements and the
schedules are shown on the wiring diagrams located in
the unit control box.
Exhaust Only
Supply fan is de-energized. There is no outdoor air ven-
tilation for the duration of frost control. Enthalpy wheel
maintains rotation.
Recirculation (ERV500i Only)
The exhaust fan is de-energized. There is no outdoor
air ventilation for the duration of frost control. Enthalpy
wheel continues to rotate.
Before start-up, check the unit for obstructive packaging,
objects near or in blowers, dampers, enthalpy wheel, etc.
Once installation is complete, check all modes of opera-
tion to ensure that the unit is working properly. Close the
doors and check for operation on Low and High using the
dry contacts labeled Low-Com-High on the side of the
unit. If there is a wall control, check the operation of all
speed settings.
Units Equipped with Frost Control
When the unit is in defrost, unoccupied mode, or off, the
ventilation damper will close. The ventilation damper will
open during ventilation.
Unit Checkpoints
• Power connected, no ventilation call – Both fans
are off, frost control damper (if equipped) closes off
fresh air from outside.
• Power connected, low speed call (if equipped) – Both
fans on low speed, frost control damper (if equipped)
opens fresh air from outside and closes recirculation
opening. If unit is single speed, it will come on that
speed on a call for low or high.
• Power connected, high speed call – Both fans on
high speed, frost control damper (if equipped) opens
fresh air from outside and closes recirculation open-
ing. If unit is single speed, it will come on the speed
on a call for low or high.
• Power connected, occupied timer/sensor connection
open (unoccupied mode) – Both fans are off, frost
control damper (if equipped) closed off fresh air from
outside.
• Power connected, enthalpy control contacts closed,
unit ventilating – Wheel stops rotating, fans stay on
set speed, frost control damper (if equipped) is open.
• Power connected, enthalpy control contacts closed,
unit not in ventilation mode – Wheel does not rotate,
fans come on low speed (if equipped), if unit is single
speed, it will come on that speed on a call for low or
high, frost control damper (if equipped) is open.
• Power connected, recirculation defrost (optional) is
factory installed – Recirc contacts are closed, exhaust
fan is de-energized, supply fan runs and recirculation
damper opens (ERV500i only).
For proper performance the unit must operate with equal
supply and exhaust flow rates. Permanent or temporarily
field supplied and installed flow measuring stations (FMS)
and magnehelic gauges can be used to measure and com-
pare supply flow with exhaust flow. Appendix D shows
proper installation of the FMS in the “exhaust air from
space” and “supply air to space” ducts for measuring ex-
haust and supply flows respectively.
It is important to locate the FMS in the “warm side” duc-
twork as described above to minimize the effect of dif-
ferences in air density, especially when balancing during
extreme cold outside conditions. Air density variations can
effect the FMS by more than 15%.
The FMS should be located downstream from straight
sections of duct and not immediately after fans or obstruc-
tions that will cause turbulent flow. See Appendix D which
illustrates minimum distances from fan, elbows or transi-
tions for best operation.
Frost Control
Sequence of Operation
Airflow Balancing
IMPORTANT
On initial power up, the unit will perform a system check
and operate at high speed for five seconds.