9
Model PV
e
Heat Recovery Unit
Electrical Information
The unit must be electrically grounded in accordance
with the current National Electrical Code, ANSI/
NFPA 70. In Canada, use current CSA Standard
C22.1, Canadian Electrical Code, Part 1. In addition,
the installer should be aware of and comply with
any local ordinances or electrical power company
requirements that might apply. System power wiring
must be properly fused and conform to the local and
national electrical codes. System power wiring is to
the main disconnect (door interlocking disconnect
switch standard on most units) or distribution block
and must be compatible with the ratings shown on
the nameplate: supply power voltage, phase, and
amperage (Minimum Circuit Amps - MCA, Maximum
Overcurrent Protection - MOP). All wiring beyond this
point has been done by the manufacturer and cannot
be modified without affecting the unit’s agency /
safety certification.
If field installing an additional disconnect switch, it
is recommended that there be at least four feet of
service room between the switch and system access
panels. When providing or replacing fuses in a fusible
disconnect, use dual element time delay fuses and
size according to the rating plate.
If power supply is desired through the bottom of unit,
run the wiring through the curb, cut properly aligned
holes in the insulation pan and the bottom of the PVe
cabinet bottom and wire to the disconnect switch.
Seal penetrations to prevent leakage or air infiltration.
The electric supply to the unit must meet stringent
requirements for the system to operate properly.
Voltage supply and voltage imbalance between
phases should be within the following tolerances.
If the power is not within these voltage tolerances,
contact the power company prior to operating the
system.
Voltage Supply:
See voltage use range on the rating
plate. Measure and record each supply leg voltage at
all line disconnect switches. Readings must fall within
the allowable range on the rating plate.
Voltage Imbalance:
In a 3-phase system, excessive
voltage imbalance between the phases will cause
motors to overheat and eventually fail. Maximum
allowable imbalance is 2%. To determine voltage
imbalance, use recorded voltage measurements in
this formula.
Key:
V1, V2, V3 = line voltages as measured
VA (average) = (V1 + V2 + V3) / 3
VD = Line voltage (V1, V2 or V3) that
deviates farthest from average (VA)
Formula:
% Voltage Imbalance = [100 x (VA-VD)] / VA
CAUTION
If any of the original wire as supplied with the
appliance must be replaced, it must be replaced
with wiring material having a temperature rating of
at least 105ºC.
WARNING
To prevent injury or death due to electrocution or
contact with moving parts, lock disconnect switch
open.
Most factory supplied electrical components are
pre-wired. To determine what electrical accessories
require additional field wiring, refer to the unit-specific
wiring diagram located on the inside of the unit
control center access door. The low voltage control
circuit is 24 VAC and control wiring should not exceed
0.75 ohms.
Refer to Field Control Wiring Length/Gauge table for
wire length maximums for a given wire gauge.
Control wires should not be run inside the same
conduit as that carrying the supply power. Make sure
that field supplied conduit does not interfere with
access panel operation.
If wire resistance exceeds 0.75 ohms, an industrial-
style, plug-in relay should be added to the unit
control center and wired in place of the remote
switch (typically between terminal blocks R and G
on the terminal strip (refer to Typical Control Center
Components). The relay must be rated for at least
5 amps and have a 24 VAC coil. Failure to comply
with these guidelines may cause motor starters to
“chatter” or not pull in which can cause contactor
failures and/or motor failures.
Field Control Wiring Length/Gauge
Total
Wire Length
Minimum
Wire Gauge
125 ft.
18
200 ft.
16
300 ft.
14
450 ft.
12
