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Utility Interface
With Infinity Control
The input labeled UTIL is active only when a communicating
Infinity Control is used. This input allows a power utility device to
interrupt compressor operation during peak load periods. See Fig.
13 for wiring connections. When the utility sends a signal to shut
the
system
down,
the
"CURTAILMENT ACTIVE".
INFINITY BOARD
R
UTILITY RELAY
UTILITY SIGNAL
OPEN RELAY
*
SUPPLIED BY UTILITY PROVIDER
Fig. 14 --- Utility Interface
With Non–Communicating Thermostats
When
the utility
curtailment interface is used
non–communicating thermostat, the utility relay should be wired
between R and Y.
Low Ambient Cooling
When this unit is operating below 55_F/12.78_C outdoor
temperature, provisions must be made for low ambient operation.
Infinity Controlled low ambient cooling:
This unit is capable of low ambient cooling without a kit ONLY
when using the Infinity control. A low ambient kit is not required,
and the outdoor fan motor does not need to be replaced for Infinity
controlled low ambient operation. The Infinity Control provides
an automatic evaporator coil freeze protection algorithm that
eliminates the need for an evaporator freeze thermostat. Low
ambient cooling must be enabled in the User Interface set up. Fan
may not begin to cycle until about 40_F/4.44_C OAT. Fan will
cycle based on coil and outdoor air temperature.
Infinity controlled low ambient mode operates as follows:
S
Fan is OFF when outdoor coil temp is < (outdoor air tem-
perature + 3_F/–16.11_C) or outdoor fan has been ON
for 30 minutes. (Fan is turned off to allow refrigerant
system to stabilize.)
S
Fan is ON when outdoor coil temp > (outdoor air temperat-
ure + 25_F/–3.89_C) or outdoor coil temp >
80_F/26.67_C or if outdoor fan has been OFF for 30
minutes. (Fan is turned on to allow refrigerant system
to stabilize.)
S
Low pressure switch is ignored for first 3 minutes during
low ambient start up. After 3 minutes, if LPS trips, then
outdoor fan motor is turned off for 10 minutes, with the
compressor running. If LPS closes within 10 minutes then
cooling continues with the outdoor fan cycling per the
coil temperature routine listed above for the remainder of
the cooling cycle. If the LPS does not close within 10
minutes, then the normal LPS trip response (shut down
cooling operation and generate LPS trip error) will occur.
Standard Thermostat low ambient cooling mode:
A Low Ambient Pressure Switch kit, Evaporator Freeze
Thermostat and Isolation Relay must be installed for low ambient
operation in standard thermostat mode. The fan motor is a
ball–bearing type and does not need to be changed. A crankcase
heater must be installed. See Product Data for part numbers on
appropriate unit size and series units.
User
Interface
will
display
UTIL
*
A05410
with a
DEFROST
This control offers 4 possible defrost interval times: 30, 60, 90 or
120 minutes. These are selected by dip switches on the unit control
board, or in the Infinity control (if used). The Infinity Control
selection overrides the control board dip switch settings.
Auto defrost is available with Infinity communicating control only
and it must be enabled in the User Interface. Auto defrost adjusts
the defrost interval time based on the last defrost time as follows:
S
When defrost time is < 3 minutes, the next defrost
interval = 120 minutes
S
When defrost time is 3–5 minutes, the next defrost
interval = 90 minutes
S
When defrost time is 5–7 minutes, the next defrost
interval = 60 minutes
S
When defrost time is > 7 minutes, the next defrost
interval = 30 minutes
The control board accumulates compressor run time. As the
accumulated run time approaches the selected defrost interval time,
the control board monitors the coil temperature sensor for a defrost
demand. If a defrost demand exists, a defrost cycle will be initiated
at the end of the selected time interval. A defrost demand exists
when the coil temperature is at or below 32_F/0_C for 4 minutes
during the interval.
The defrost cycle is terminated when the coil temperature reaches
65_F/18.33_C or 10 minutes has passed.
If the coil temperature does not reach 32_F/0_C within the interval,
the interval timer will be reset and start over.
NOTE:
S
Upon initial power up the first defrost interval is defaulted
to 30 minutes. Remaining intervals are at selected times.
S
Defrost is only allowed to occur below 50_F/10_C outdoor
ambient temperature.
Defrost Hold
In a non–communicating system, if the thermostat becomes
satisfied before the defrost cycle is terminated, the control will
"hold" in defrost mode and finish the defrost cycle on the next call
for heat. Defrost hold is not needed in a communicating system
because the User Interface will complete the defrost cycle before
shutting down the system.
Forced Defrost
Forced defrost can be initiated manually in a non–communicating
system, or by communicated command from a User Interface. The
board contains a 2–pin header labeled FORCED DEFROST (see
Fig. 12). To initiate a forced defrost:
S
Manually, short
FORCED DEFROST pins
seconds then release
S
If coil temp is at defrost temp of 32_F/0_C, and outdoor
air temperature is below 50_F/10_C, a full defrost se-
quence will occur
S
If the coil temp or outdoor air temperature do not meet
the above requirements, an abbreviated 30 second de-
frost will occur
S
The Quiet Shift–2 compressor on/off delays, as described
below, will be included in a forced defrost if Quiet
Shift–2 is enabled.
QUIET SHIFT–2
Quiet Shift–2 is a field selectable defrost mode which may
eliminate occasional noise that could be heard at the start and finish
of the defrost cycle.
On a non–communicating system, this feature must be enabled by
selecting the 3rd position of the 3–position dip switch on the
outdoor control board. For communicating systems, it must be
enabled at the User Interface. When activated, the following
sequence of operation occurs: Defrost Initiation – the compressor
10
for 5
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