Friedrich 9 - Manual (Page 18)

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VPak ELECtRonIC ContRoL BoaRD anD waLL
tHERmoStat SEqUEnCE oF oPERatIon
Wall Thermostat Connections:
• The control is compatible with a standard single stage heat and cool Wall
Thermostat.
• It is compatible with Friedrich RT4 and RT5 Wall thermostats.
• Terminals are:
C – Common ground terminal.
W – call for heating.
Y – call for cooling,
R – 24V power from Electronic control to Wall Thermostat.
GL - call for low Fan.
GH- call for high fan
B – call for heat pump reversing valve.
The outputs of a single stage Heat and Cool Wall thermostat:
• When a call for cool from Wall thermostat the signals will go to
terminal Y, GL or GH.
• When a call for heat from Wall thermostat the signals will go to
terminal W, B, GL or GH.
• When a call for Fan Only from Wall thermostat the signals will go
to terminal GL or GH.
Remote T-stat Operation Features:
All buttons on the electronic control board will be disabled except “Heat”
When power is applied to L1 and L2, the Power LED will be lit on the
electronic control.
and “High Fan” buttons during Error code mode operation.
COMMON CONTROL FEATURES FOR COOL WITH ELECTRIC HEAT
AND HEAT PUMP WITH ELECTRIC HEAT UNITS:
Power On and Off Features on the Electronic Control:
Temperature set:
This feature will depend on Wall Thermostat.
˚F/˚C set:
This feature will depend on Wall Thermostat.
Fan speed, fan cycle on/off or continuous operation
This feature will depend on Wall Thermostat. For single speed Wall
Thermostat, user needs to choose between GH terminal (High Fan) or
GL terminal (Low Fan). For a two speed fan Wall Thermostat, connect
both GL and GH. If the PCB receives signals for both GL and GH at the
same time, only High Fan turns on.