EcoNet P16AZ24A - Sequence of Operation for Conventional 24 VAC Thermostat Controls

33
Operation
NOTE: Should the outdoor ambient
temperature thermistor fail, the VSODC
will initiate a defrost every 34 minutes of
operation when the coil temperature is
below 35°F.
6.7 Sequence
of Operation for
Conventional 2-Stage
24VAC Thermostat
Controls
The (-)A15AZ/(-)P16AZ/(-)A16AZ unit will have
variable capacity from 45% to 65%. A compres-
sor demand above 65% capacity shall switch
the inverter operation to line voltage. This type
of hybrid operation shall either take place when
connected to a communicating indoor unit and a
non-communicating thermostat.
In legacy mode, the outdoor control shall deter-
mine the compressor speed.
The difference between the temperature set-
point and the room temperature measured at
the 24VAC 2-stage thermostat will determine
whether the system gets a cooling or heating
call. Upon a cooling/heating call, the VSODC
will command the air-handler or gas furnace
control board to deliver an appropriate indoor
air-flow level based on the capacity using the
parameters stored internally to the UODC. One
second after the compressor starts, the VSODC
will direct the variable speed outdoor motor to
operate at the appropriate speed to deliver the
necessary outdoor air-flow for that capacity
based on the parameters stored in the UODC.
As the building load changes throughout the call
for cooling/heating operation, the compressor
speed, outdoor fan speed, and indoor air-flow
level will respond by ramping up or down as
required to meet the building load exactly rather
than simply cycling on and off as conventional
systems do. When the call for cool ing/heating
has ended, the call from the 2-stage thermo-
stat will be removed and the UODC will direct
the outdoor and indoor units to shut down. The
compressor and outdoor fan motor will ramp
down to zero RPM and the indoor blower motor
will ramp down to the minimum air-flow level for
30-45 seconds to extract the residual heating
from the cold indoor coil before it stops.
Note: Anytime the compressor goes to line
operation, the unit shall stay there until the
heating/cooling satisfies the thermostat
demand
6.0 NORMAL SEQUENCE OF OPERATION
Off
On
Off
On
Off
Off
On
On
60
º
F [15.6
º
C]
50
º
F [10
º
C]
40
º
F [4.4
º
C]
70
º
F [21.1
º
C]
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