Product Overview

BAC-1xx63/1xxx63 Series (6 Relays and 3 Analog Outputs) Section 53 Application Guide S
temperature above the active heating setpoint minus one half
the heating proportional band, the second stage of compressor
will be de-energized. Upon further rise in temperature above
the active heating setpoint, the rst stage of compressor will be
de-energized. In the cooling mode, if the space temp rises above
the active cooling setpoint plus one half the cooling proportional
band AND the rst stage of compressor has been o for at least
the minimum o time, the rst stage of compressor will be en-
ergized. If the space temp further rises above the active cooling
setpoint plus the cooling proportional band AND the rst stage
of compressor has been energized for at least the stage delay
AND the second stage of compressor has been o for at least the
minimum o time, the second stage of compressor will be en-
ergized. Upon decrease in space temp below the active cooling
setpoint plus one half the cooling proportional band, the second
stage of compressor shall be de-energized. Upon further decrease
in space temp below the active cooling setpoint, the rst stage of
compressor shall be de-energized.
If at any time there is a fan failure alarm or low limit alarm, all com-
pressor stages are de-energized.
Auxiliary/Emergency Heat
The heat pump application can be congured with auxiliary heat in
three methods: no auxiliary heat, auxiliary heat with outside air temp
compressor lockout, and auxiliary heat without outside air temp com-
pressor lockout.
If the unit is congured for auxiliary heat without compressor lock-
out, the auxiliary heat and emergency heat function as third and fourth
stages of heat. If the space temperature drops below the active heating
setpoint minus 1.5 times the heating proportional band and remains
below that temperature for the Auxiliary Heat Delay (adjustable), the
auxiliary heat is energized. If the space temperature further falls below
the active heating setpoint minus 2 times heating proportional band and
the auxiliary heat is energized, the emergency heat is then energized. If
the space temperature rises above the active heating setpoint minus 1.5
times heating proportional band, the emergency heat is de-energized. If
the space temp further rises above the active heating setpoint minus the
heating proportional band, the auxiliary heat is de-energized.
If the heat pump application is congured for auxiliary heat with com-
pressor lockout, a compressor lockout mode is enabled if the outside air
temperature drops 1.0° F (0.56° C) below the Compressor OAT Low Limit.
The compressor lockout mode is disabled if the outside air temperature
rises 1.0° F (0.56° C) above the Compressor OAT Low Limit. If the com-
pressor lockout mode is disabled, the auxiliary and emergency heat func-
tion as described above. If the compressor lockout mode is enabled, all
stages of compressor are de-energized and the auxiliary and emergency
heat function as described above but without the Auxiliary Heat Delay.
If the System Mode is set to “Emer Ht,” the compressors are locked out
and the auxiliary and emergency heat stage operate as follows:
If the space temp drops below the active heating setpoint minus one
half the heating proportional band, the auxiliary heat is energized. If
the space temp further falls below the active heating setpoint minus the
heating proportional band AND the auxiliary heat has been energized
for at least the stage delay, the emergency heat is energized. Upon rise in
temperature above the active heating setpoint minus one half the heat-
ing proportional band, the emergency heat will be de-energized. Upon
further rise in temperature above the active heating setpoint, the auxil-
iary heat will be de-energized.
Any time there is a fan failure alarm or low limit alarm, auxiliary and
emergency heating are de-energized.
Economizer Control
If the HPU application is congured for the economizer option, the base
economizer sequence described in the Common Features section is followed.
Dehumidification
Upon activation of the dehumidication mode, congured stages of
compressor are energized after they have been o for at least the mini-
mum o time. The reversing valve is set to the cooling mode based on
the reversing valve conguration. Auxiliary and emergency heating
stages then follow their normal sequence to maintain the active heating
setpoint.