Page 43
XP25
Reconfiguring Outdoor Control using
iComfort Wi-Fi
®
Thermostat
If any component of the HVAC system is changed, ( e.g. an
outdoor sensor is replaced), reconfigure the system. To
begin reconfiguring a system, select the
Setup
tab.
System Overview
Refer to the iComfort Wi-Fi
®
Thermostat Installer Guide for
configuration procedures.
IMPORTANT
Some scroll compressors have internal an vacuum
protector that unloads the scrolls when suction pressure
drops below 20 psig. A hissing sound is heard when the
compressor is running unloaded. Protector resets when
low pressure in system is raised above 40 psig. DO NOT
REPLACE COMPRESSOR.
The outdoor control provides the following functions:
•
Demand defrost algorithm
•
Field-selectable defrost termination temperatures
through the thermostat interface
•
Internal switching of outputs
•
Anti-short-cycle delay (adjustable through the
thermostat interface
•
Five-strike lockout function
•
Ambient (RT13), coil (RT21) and liquid line (RT36)
temperatures monitoring and protection
COMPRESSOR PROTECTION — FIVE-STRIKE
LOCKOUT FUNCTION
The five-strike lockout function is designed to protect the
unit's compressor from damage. The five-strike feature is
used for high (S4) and low (S87) pressure switch trips.
Resetting Five-Strike Lockout
Once the condition has been resolved, power to the outdoor
control
R
terminal must be cycled
OFF
.
Diagnostic Information
The following diagnostic information is available through the
thermostat user interface. Refer to the Wi-Fi
®
Installer
System Setup Guide.
•
Compressor anti-short cycle delay timer status
•
Cooling rate
•
Heating rate
•
Compressor shift delay timer status
•
Defrost status
•
High pressure switch status
•
Low pressure switch status
•
Compressor top cap switch status
•
Liquid line temperature
•
Outdoor ambient temperature
•
Coil temperature
•
Time since last defrost
•
Calibration delta T
•
Current delta T
•
Outdoor fan RPM
•
Compressor active alarm
•
Compressor Hz
•
Inverter compressor short cycle
•
Heat sink temperature
Installer Test
Verify the proper operation of the system by running the
Installer Test feature through the thermostat interface. Refer
to the iComfort Wi-Fi
®
Installer's System Setup Guide.
Defrost Function
The outdoor unit control measures differential temperatures
to detect when the system is performing poorly because of
ice build-up on the outdoor coil. The controller self-calibrates
(see figure 33) when the defrost system starts and after each
system defrost cycle. The outdoor unit control monitors
ambient temperature, outdoor coil temperature, and total
run-time to determine when a defrost cycle is required. The
coil temperature sensor is designed with a spring clip to
secure the sensor to the outside coil tubing. The location of
the coil sensor is important for proper defrost operation (see
figure 59 on page 77 for location of coil sensor).
NOTE - The outdoor unit control accurately measures the
performance of the system as frost accumulates on the
outdoor coil. This typically translates into longer running time
between defrost cycles as more frost accumulates on the
outdoor coil before the outdoor control initiates defrost
cycles.
DEFROST OPERATING MODES
The outdoor control has three operational modes:
•
Defrost calibration (see figure 33)
•
Operation
•
Defrost test
DEFROST TERMINATION TEMPERATURES
The defrost termination temperature setting selections (50,
70, 80, 90, and 100°F) are available through the thermostat
interface. The factory default setting is
50°F (10°C)
.
NOTE - Colder climates may require a higher discharge
termination temperature setting to maintain a clear coil.
