Specifications

22
RG SERIES ENGINEERING GUIDE
Controls - FX10 (optional) cont.
Emergency Heat/Network Enabled Output (BO5)
This output is set from the factory to enable/disable emergency
heat. If a problem occurs with the unit resulting in the compressor
being locked out in heating mode, the control will automatically
enable this output to turn on field installed electric heat. This
output is interlocked with the blower proving input BI-6 (Blower
proving sensors must be field supplied and installed). BI-6 must be
connected to PB2 position 3 (see unit schematic) in the field if no
blower proving sensor is desired. There is a configurable parameter
available through a BAS network that must be enabled if this output
is to be commanded over the BAS network.
MUI Alarm History Reporting
If a fault occurs the fault will be recorded in history for display on
the medium user interface in the History Menu. Each fault type will
be displayed in the history menu with a number between 0 and 3.
A reading of 3+ will mean that fault has occurred more than three
times in the past. The history menu can be cleared with a power
cycle only. Alarm date and time are not included in the history.
Inputs and Outputs Configuration
Field Selectable Options
Freeze Detection Set Point (BI-5)
The freeze detection set point input allows you to adjust the freeze
detection set point (AI-5). When the jumper is installed on BI-5 (Wire
#24) the freeze detection set point is factory set for 30°F (-1°C).
When the jumper on BI-5 (Wire #24) is removed the freeze detection
set point will be 15°F (-9°C).
Accessory Outputs (BO-7 and BO-8)
Accessory Output 1 will be energized 90 seconds prior to
the compressor output being energized. Accessory Output 2
will be energized with the blower output (BO-1). When the
corresponding compressor output is turned off the accessory
output will be deactivated immediately. These outputs are
selectable for normally open or normally closed operation through
the MUI or through the BAS.
Hot Gas Reheat Description
The refrigerant flows in normal heat pump path in heating and
cooling mode. During the Reheat mode, the operation begins
with superheated vapor leaving the compressor going through
the reheat valve to the reheat air coil. In the reheat coil the high
temperature high pressure gas reheats the air exiting the unit to
near neutral. Next, the refrigerant exits the reheat coil and passes
through a check valve, which is used to prevent refrigerant flow
into the reheat coil during normal heating and cooling operation.
The refrigerant passes through the check valve and is then
diverted to the coaxial heat exchanger by the four way reversing
valve. The hot gas enters the coaxial heat exchanger which will
condense the gas to a high pressure liquid due to heat being
rejected to the loop fluid. The high pressure liquid leaves the coax
and enters the inlet of the TXV. After passing through the TXV the
low pressure mixture of liquid/vapor refrigerant expands in the
air coil evaporating into a low pressure low temperature gas and
moves back through the reversing valve and into the compressor
suction. The cycle then starts again by compressing the low
pressure low temperature gas into a superheated vapor. A small
copper bleed line is located on the reheat/reclaim valve to allow
refrigerant that has migrated to the reheat coil to escape.
Hot Gas Bypass Description
The hot gas bypass (HGB) option is designed to limit the minimum
evaporating pressure in the cooling mode to prevent the air coil
from icing. The HGB valve senses pressure at the outlet of the
evaporator by an external equalizer. If the evaporator pressure
decreases to 115 psig the HGB valve will begin to open and
bypass hot discharge gas into the inlet of the evaporator. The
valve will continue to open as needed until it reaches its maximum
capacity. Upon a rise of suction pressure, the valve will begin to
close back off and normal cooling operation will resume.
Hot Gas Reheat/Hot Gas Bypass