19
E SERIES INSTALLATION MANUAL
Optional FX10 Microprocessor Control
The Johnson Controls FX10 board is specifically designed for commercial heat pumps and provides control of the entire unit
as well as input ports for N2 Open, LonTalk, BacNet communication protocols as well as an input port for a user interface.
The user interface is an accessory item that can be used to aid in diagnostics and unit setup. A 16 pin low voltage terminal
board provides terminals for common field connections.
FX10 Operation
Startup
The unit will not operate until all the inputs and safety controls are checked for normal operating conditions.
Fault Retry
All faults are tested twice before finally locking the unit out to prevent nuisance service calls.
Component Sequencing Delays
Components are sequenced and delayed for optimum unit performance. See table below.
CONTROL TIMING
Lead compressor ON delay
30 seconds
Short cycle delay
4 minutes
Minimum compressor ON time
2 minutes (except for fault condition)
High pressure fault recognition
Less than 1 second
Low pressure fault recognition delay
30 seconds
Freeze protection fault recognition delay
30 seconds
Condensate overflow fault recognition delay
30 seconds
Low pressure fault bypass delay
2 minutes
Freeze protection fault bypass delay
2 minutes
Random start delay
0-120 seconds
Short Cycle Protection
The control allows a minimum compressor off time of 4 minutes and a minimum compressor run time of 2 minutes for
short cycle protection.
Random Start
A random start delay of 1 to 120 seconds is generated after each power up to prevent simultaneous startup of all units
within a building after the release from an unoccupied cycle or power loss.
Emergency Shutdown
A normally open dry contact must be placed between DI2 and PB2-L2. Closing the contact will set the unit into emer-
gency shutdown mode. All unit operation is suspended while in emergency shutdown mode.
Condensate Overflow Protection
The board incorporates an impedance liquid sensor at the top of the condensate drain pan. Upon a continuous 30-
second sensing of the condensate, the operation of the unit is suspended.
Safety Controls
The FX10 board receives separate signals from a high pressure switch for safety, a low pressure switch to detect loss
of refrigerant charge and a low suction temperature thermistor for freeze protection. Upon a continuous 30-second
measurement of the fault (immediate for high pressure), compressor operation is stopped.
Freeze Protection
Note:
For applications using a closed loop antifreeze solution, remove the wire between DI5 and PB2-L1 (see unit
schematic). On applications using an open loop/ground water system, make sure the wire is connected.
Note:
For additional information on the FX10 Control, refer to Application Guide AGFX10 or Submittal Data SD1981.
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