Specifications

Frost Control
The unit functions are controlled by an integrated mi-
croprocessor control board included in the unit as per
the frost control selected, the sequence of operation as
described below and according to the options selected as
described in Appendix F.
Exhaust Only Defrost
The exhaust only frost control cycle is electronically con-
trolled in response to outside air temperature. On a call for
defrost, the outside air damper and the heat exchanger
core damper close, the supply fan is de-energized and the
exhaust fan continues to draw warm room air through
the flat plate heat exchanger to remove the buildup of ice.
Frost control is initiated at an outdoor temperature of 23°F
[−5°C].The defrost/ventilation cycle is time and tempera-
ture based per Table 4.
Recirculation Defrost
The recirculation frost control cycle is electronically con-
trolled in response to the outside air temperature. On a
call for defrost, the outside air damper closes, the exhaust
fan is de-energized, the exhaust gravity backdraft and/or
motorized damper closes, the recirculation defrost damper
opens and the supply fan circulates warm air through the
flat plate heat exchanger to remove the buildup of ice. For
the HRV700i, it is possible to extend the frost control times
during very cold weather by removing the jumper JU1-F on
the circuit board. Frost control is initiated at an outdoor air
temperature of 23°F [−5°C]. The defrost/ventilation cycle is
time and temperature based per Table 4.
Non-defrost
No frost control can be used only in areas where the win-
ter outdoor air condition stays above 23°F [−5°C] and the
return air humidity level is below 20%.
Sequence of Operation
Unit Check Points
• 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 – Both fans on low
speed, internal frost control damper (if equipped)
opens fresh air from outside. If equipped with recir-
culation module, the internal frost control damper
closes recirculation opening.
• Power connected, high speed call – Both fans on
high speed, frost control damper opens fresh air
from outside. If equipped with recirculation module,
the internal frost control damper closes recirculation
opening.
• Power connected, occupied timer/sensor connec-
tion open (unoccupied mode) – Both fans are off,
frost control damper closes fresh air from outside. If
equipped with recirculation module, the internal frost
control damper opens recirculation opening.
• Power connected, FF control contacts close during
unit ventilation or frost control cycle.
IMPORTANT
On initial power up, the unit will perform a system check
and operate at high speed for five seconds.
Table 4: Recirculation (R) and Exhaust Only (E) Defrost
HRV
Model
Stage
Type of
Defrost
Initiate
Temperature
Ventilation Time
(Minutes) Defrost
Time/Run Time
Standard Extended
Aluminum and Polypropylene Core Heat Exchangers
600i
1200i
1 R/E 23°F −5°C 12/60 N/A
2 R/E 5°F −15°C 12/24 N/A
3 R/E −21°F −30°C 12/12 N/A
700i
1 R 23°F −5°C 6/60 10/28
2 R 5°F −15°C 6/32 10/28
3 R −21°F −30°C 6/19 10/15
Heat and Moisture (HM) Core Heat Exchangers
600i
1200i
1 R/E 23°F −5°C 10/50 10/30
2 R/E 5°F −15°C 10/30 10/20
3 R/E −21°F −30°C 10/20 10/15
VCES-HRV-IOM-1C – HRV600i, HRV700i, HRV1200i
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