Bard H24A2-A, Manual

Page: 14 / 22

Manual 2100-585C
Page 14 of 22
WIRING – MAIN POWER
Refer to the unit rating plate for wire sizing information and
maximum fuse or circuit breaker size. Each outdoor unit is
marked with a “Minimum Circuit Ampacity”. This means
that the field wiring used must be sized to carry that amount
of current. Depending on the installed KW of electric heat,
there may be two field power circuits required. If this is
the case, the unit serial plate will so indicate. All models
are suitable only for connection with copper wire. Each
unit and/or wiring diagram will be marked “Use Copper
Conductors Only”. These instructions must be adhered to.
Refer to the National Electrical Code (NEC) for complete
current carrying capacity data on the various insulation
grades of wiring material. All wiring must conform to NEC
and all local codes.
The electrical data lists fuse and wire sizes (75° C copper)
for all models including the most commonly used heater
sizes. Also shown are the number of field power circuits
required for the various models with heaters.
The unit rating plate lists a “Maximum Time Delay
Relay Fuse” or circuit breaker that is to be used with
the equipment. The correct size must be used for
proper circuit protection and also to assure that there
will be no nuisance tripping due to the momentary high
starting current of the compressor motor.
The disconnect access door on this unit may be locked
to prevent unauthorized access to the disconnect. To
convert for the locking capability, bend the tab located
in the bottom left-hand corner of the disconnect
opening under the disconnect access panel straight
out. This tab will now line up with the slot in the door.
When shut, a padlock may be placed through the hole
in the tab preventing entry.
See “Start Up” section for important information on
three phase scroll compressor start ups.
See Tables 3A and 3B for Electrical Specifications.
Low Voltage Connection
These units use a 24-volt AC low voltage circuit. The
“ RT ” terminal is the 24V transformer output, and the
“ R ” terminal is the 24VAC hot terminal for the operation
of the equipment. “
RT
” and “
R
” are connected with
brass jumper bar which can be removed and “ RT ” and
“ R ” connected to external NC (normally closed) contact
such as a fire/smoke detector that will cause immediate
shutdown of the equipment upon activation.
“
C
” terminal is
grounded
.
“ G ” terminal is the fan input .
“ Y ” terminal is the compressor input for cooling
1-Stage units only
“ W1 ” terminal is the 1st stage electric heat .
“ W2 ” terminal is the 2nd stage heat (if equipped).
“ E ”, “ F ”, “ Y2 ” & “ A ” Used with EWM-T Economizer.
“ 1 ” NO (normally open) lockout alarm.
“
2
” NC (normally closed) lockout alarm.
“ 3 ” COM lockout alarm.
“ 4 ” & “ 5 ” dirty filter alarm NC (normally closed).
“
6
” Used with MD4000 only; do not use for anything else!
“ Y1 ” & “ 7 ” Used with EWM-T Economizer; do not use
for anything else!
“ 8 ” & “ 9 ” ECON Fail Alarm.
WIRING – LOW VOLTAGE WIRING
230/208V, 1 phase and 3 phase equipment dual primary
voltage transformers. All equipment leaves the factory
wired on 240V tap. For 208V operation, reconnect
from 240V to 208V tap. The acceptable operating
voltage range for the 240 and 208V taps are:
TAP RANGE
240 253 – 216
208 220 – 187
NOTE: The voltage should be measured at the field
power connection point in the unit and while
the unit is operating at full load (maximum
amperage operating condition).
For H model units with Y or Z vent option economizers,
refer to the MV4000 Series Lead/Lag Controller manual
2100-571 for low voltage connection diagrams. Factory
installed Y and Z vent option are wired per Figure 7 of
2100-571.
DIRTY FILTER SWITCH AND RELAY
These units include a dirty filter switch and relay. The
alarm output of relay is normally closed, open on alarm
and is connected to terminals 4 and 5 of the unit low
voltage terminal block.
ECONOMIZER FAIL TIME DELAY RELAY
NOTE: Applies only to units with economizers.
These units employ a time delay relay used in
conjunction with the 100% Economizers to provide an
economizer fail alarm. The alarm output is connected
to terminals 8 and 9 of the low voltage terminal block.
The time delay should be set to no less than 3 minutes
to ensure no nuisance alarms.

MIS-3054
TIMER TO BE
SET HERE
MIS-3054