Compu-aire SYSTEM 2500 User manual

Rev.01 03-27-17
Page 1 of 71
Compu-Aire
SYSTEM 2500
PROGRAMMABLE CONTROLLER
-USER MANUAL-
8167 Byron Road Whittier, CA 90606
Phone: [phone] Fax: [phone]
SUBJECT TO CHANGE WITHOUT INCURRING OBLIGATION

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Compu-Aire
Table of Contents
1.0 INTRODUCTION.....................................................................................................................................7
2.0 QUICK REFERENCE GUIDE .....................................................................................................................8
3.0 SEQUENCE OF OPERATIONS ...............................................................................................................11
3.1 Standard Units in General...........................................................................................................11
3.2 How to Turn the Unit ON ............................................................................................................11
3.3 Lead/Lag Redundancy –pLAN Network......................................................................................11
3.4 Air Cooled DX with Chilled Water Plus........................................................................................12
3.5 Air Side Economizer ....................................................................................................................14
3.6 Water Side Economizer Energy miser (EM) Unit Using 2-Way Valves........................................14
3.7 Water Cooled Energy Miser........................................................................................................15
3.8 Dry Fluid Cooler with Energy Miser ............................................................................................17
3.9 Special Pump and Dry Fluid Cooler control logic........................................................................19
3.10 Optional features ........................................................................................................................20
4.0 CONFIGURATION.................................................................................................................................20
4.1 Software version .........................................................................................................................20
5.0 TECHNICAL SPECIFICATIONS ...............................................................................................................21
5.1 Controller and Display.................................................................................................................21
5.2 General Characteristics...............................................................................................................21
5.3 Mechanical Characteristics .........................................................................................................22
5.4 Electrical Characteristics .............................................................................................................22
5.5 Digital Inputs ...............................................................................................................................23
5.6 Universal inputs ..........................................................................................................................24
5.7 Analog Outputs ...........................................................................................................................25
5.8 Digital Outputs ............................................................................................................................25
5.9 Cable Length ...............................................................................................................................25
5.10 Standard Input / Outputs............................................................................................................26
5.11 Optional Features .......................................................................................................................27
5.12 Functional characteristics ...........................................................................................................27
5.13 Building Management System ....................................................................................................27

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6.0 Navigation Menu.................................................................................................................................28
7.0 Factory Setup ......................................................................................................................................43
7.1 Universal Inputs ..........................................................................................................................43
7.2 Analog Output.............................................................................................................................44
7.3 Digital Inputs ...............................................................................................................................45
7.4 Digital Outputs ............................................................................................................................46
7.5 HVAC ...........................................................................................................................................47
7.6 Loading System Default ..............................................................................................................48
7.7 Password.....................................................................................................................................49
7.8 Clock Setup..................................................................................................................................49
7.8.1 Night Setback ......................................................................................................................49
8.0 BUILDING MANAGEMENT SYSTEM (BMS) ..........................................................................................50
8.1 Modbus .......................................................................................................................................51
8.1.1 Mounting.............................................................................................................................51
8.2 LONWORKS .................................................................................................................................53
8.2.1 General characteristics .......................................................................................................53
8.2.2 Physical channels ................................................................................................................53
8.2.3 Physical Circuit Board Layout..............................................................................................53
8.2.4 LED Color Description .........................................................................................................54
8.2.5 Installation ..........................................................................................................................54
8.2.6 Connection to the Controller ..............................................................................................55
8.2.7 Connection to the LonWorks® network..............................................................................55
8.2.8 Service pin...........................................................................................................................55
8.2.9 WINK event .........................................................................................................................56
8.3 BACNET OVER TCP/IP For BMS Card Add ON .............................................................................57
8.3.1 Installation ..........................................................................................................................57
8.3.2 Functions.............................................................................................................................57
8.3.3 Default parameters.............................................................................................................57
8.3.4 Restarting the software ......................................................................................................58
8.3.5 Configuration ......................................................................................................................58
8.3.6 Web server..........................................................................................................................60

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8.3.7 Accessing the operating system by authentication ............................................................60
8.3.8 CGI script.............................................................................................................................61
8.3.9 SNMP...................................................................................................................................61
8.3.10 BACNET ...............................................................................................................................61
8.3.11 WARNINGS..........................................................................................................................62
8.4 BANET over MS/TP For BMS Card add on...................................................................................63
8.4.1 Installation ..........................................................................................................................63
8.4.2 Meaning of the jumpers......................................................................................................64
8.4.3 Operation............................................................................................................................64
8.4.4 Recalling the factory configuration (“factory bootswitch” mode) .....................................66
8.4.5 Configuration ......................................................................................................................66
8.4.6 BACNET Parameter Description..........................................................................................67
9.0 TROUBLESHOOTING GUIDE ................................................................................................................68

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Table of Figures
Figure 1 User Interface..................................................................................................................................8
Figure 2 Software information....................................................................................................................20
Figure 3 Optional External display ..............................................................................................................21
Figure 4 System 2500 controller.................................................................................................................21
Figure 5 power connection .........................................................................................................................22
Figure 6 Digital inputs .................................................................................................................................23
Figure 7 Analog outputs..............................................................................................................................25
Figure 8. Menu tree ....................................................................................................................................28
Figure 9. Alarm Status.................................................................................................................................29
Figure 10. Universal inputs .........................................................................................................................30
Figure 11. Universal outputs.......................................................................................................................30
Figure 12. Optional sensors ........................................................................................................................31
Figure 13. Communication ports ...............................................................................................................31
Figure 14. BMS2 (RS-485) setup .................................................................................................................31
Figure 15. Trending plot..............................................................................................................................32
Figure 16. Schedule.....................................................................................................................................33
Figure 17. Sensor calibration ......................................................................................................................34
Figure 18. Display setup..............................................................................................................................35
Figure 19. Manual controls .........................................................................................................................35
Figure 20. Network p-LAN menu................................................................................................................36
Figure 21. IP address..................................................................................................................................37
Figure 22. Rotation schedules....................................................................................................................37
Figure 23. Network configuration..............................................................................................................38
Figure 24. Network scan ............................................................................................................................38
Figure 25. IP Configuration ........................................................................................................................39
Figure 26. Network rotation map ..............................................................................................................40
Figure 27. Network setup...........................................................................................................................41
Figure 28. Network Assist ..........................................................................................................................42
Figure 29. Factory setting analog inputs....................................................................................................43
Figure 30. Factory Analog Outputs ............................................................................................................44
Figure 31. Digital Inputs .............................................................................................................................45
Figure 32. Digital Outputs ..........................................................................................................................46
Figure 33. Evap PID tuning .........................................................................................................................47
Figure 34. DX compressor PID tuning ........................................................................................................47
Figure 35. Heat PID tuning .........................................................................................................................47
Figure 36. Humidity PID tuning..................................................................................................................47
Figure 37. Dehumidification PID tuning.....................................................................................................48
Figure 38. Chilled water PID tuning ...........................................................................................................48
Figure 39. Economizer PID tuning..............................................................................................................48

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Figure 40. Assist PID tuning........................................................................................................................48
Figure 41. Hotgas bypass PID tuning..........................................................................................................48
Figure 42. Condenser fan PID tuning .........................................................................................................48
Figure 43. Password management.............................................................................................................49
Figure 44 Date and time..............................................................................................................................49
Figure 45. Night setback.............................................................................................................................50
Figure 46 - Building management system...................................................................................................50
Figure 47 - Communication protocol..........................................................................................................50
Figure 48 - LONTalk Card ............................................................................................................................53
Figure 49 - Remove plastic cover................................................................................................................55
Figure 50- Cut out window .........................................................................................................................55
Figure 51 - Installing plugin card.................................................................................................................55
Figure 52 - Replacing windows cover..........................................................................................................55
Figure 53 - PCOWeb....................................................................................................................................60
Figure 54 - Window cover...........................................................................................................................60
Figure 55 - Installing PCOWeb ....................................................................................................................60
Figure 56 - Installing plastic cover...............................................................................................................60

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1.0 INTRODUCTION
The System 2500 is a programmable controller based on a double microprocessor, designed for
precise "Smart" control of an air conditioning system. The System 2500 is made up of a
microprocessor based MAIN BOARD equipped with a set of terminals used to interface the
microcontroller board to the controlled devices such as compressors, fans, heaters, humidifiers,
and valves. The program is retained in a flash based memory and configuration parameters are
permanently stored (even in the case of a power failure) in a non-volatile memory.
The System 2500 also includes a microprocessor based TERMINAL unit complete with graphical
touch screen display with built in navigation keypad and LED indicators allowing the users to
easily set the controlled parameters for setpoints, dead bands, alarm thresholds, and carry out
the main working operations (on/off, displaying controlled variables, printouts). The controller
and graphical display terminal are powered by 24VAC power supply using low voltage control
transformers from the unit. Connection between the terminal unit and main board is necessary
only when programming the System 2500 basic parameters. The controller is linked to a graphic
display terminal via standard three wire cable.
The System 2500 represents the evolution of the microcontroller towards the networking
capabilities with integrated Ethernet interfaces. It offers a wide range of open stand protocols
for local connectives. The new operating system is optimized to ensure optimal system resource
usage and increase speed and reliability.

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2.0 QUICK REFERENCE GUIDE
The controller is fully programmed and pre-configured per system configuration. Further
modification may be required to better fit the application.
Figure 1 User Interface
1
Power/Link LED
Solid green: Normal operation
Flashing green: loss communication
OFF: No power
2
High contrast frame
3
Touch sensitive screen
Table 1 Touchscreen interface
2
3
1

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Compressor stage
Active: Green
OFF: Black
Heating stage
Active: Red
OFF: Black
Demand output
Pumpdown mode
Evaporator fan
Humidifier mode
Cooling mode
Dehumidification
mode
Heating mode
Econ/cooling assist
mode
Table 2 Icon legends
1
2
3
4
5
6
7
8

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1Room temperature and relative humidity
2Room return temperature and humidity setpoints
3Cooling stages
4Mode of operation
5System ON/OFF control
6System demands/outputs
7Heating stages
8Navigation system
Main menu
Alarm menu
Next menu
Previous menu
Table 3 Menu Options

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3.0 SEQUENCE OF OPERATIONS
3.1 Standard Units in General
In general, the controller is operated as follows:
NOTE: The following are applicable while the controller is in active mode and only apply to DX and
Chilled Water units.
•Fan starts up on demand for cooling, heating, humidifying or dehumidifying, or operates
continuously.
•Sequences the compressors on in stages with adjustable delays to meet demand for
specified temperature and humidity setpoints.
•Sequences the heaters on in stages with programmable delays to meet demand for heating
or reheat during dehumidification mode.
•Activates the humidifier as needed to meet the humidity demand.
•Dehumidification is achieved by means of cooling to reduce the humidity level. During the
dehumidification process, if the temperature falls below the room setpoint, heating is
brought on to reheat the air and maintain room temperature.
•The controller monitors the complete system for any sensor, fan, compressor, heater,
and/or humidifier failure. Upon critical failures, the complete system will shut down with
alarm. For certain component failures, the applicable feature is disabled to ensure safe
operation. For example, when compressor failure occurs, the failed compressor shall be
locked out but the system shall provide cooling by other compressor if available. On a
heater failure, the heaters are locked out. The system will not use that function until you
manually reset on the display. The controller also keeps the history of last 100 alarms after
you reset them.
3.2 How to Turn the Unit ON
From the status screen, navigate to the On/Off menu and press enter. Use the Up/Down
arrow buttons to toggle the On/Off operation.
The System Status screen should indicate the current system operating mode.
Default time delay for evaporator fan is 30 seconds to avoid short cycling.
Unit will automatically control the necessary mode of operation to maintain room setpoints.
3.3 Lead/Lag Redundancy –pLAN Network
System 2500 series controllers can be set for n+1 redundancy setup. A maximum of 32 units can
be linked together on the pLAN network. The pLAN networked systems are identified by IP
addresses. Any system within the network can be configured as master unit. This alleviates the
need to cumbersome wiring with the use of standard Ethernet cables. In case of master unit is out
of service, any of the slave units can be set as a new master to reduce network downtime. No
wiring changes are needed. Each controller is self-dependent with necessary sensors and it can be

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used as a stand-alone unit. When used on the pLAN Network, each unit is not required to have to
have the same software revision and date.
When the Master goes offline, all standby systems become active to standalone mode. This
reduces the chance of the controlled space temperature and humidity trailing off setpoints.
When an active unit with either Master or Slave goes into alarm, the next standby system or all
standby systems should become active. Network alarm events are programmable via the
technician menu. Communication between systems is maintained by a synchronized heartbeat.
Unit rotation can be set to achieve equal run time on. At the end of each cycle, the role of each
unit switches to its counterpart, meaning the Master becomes the Slave and the Slave becomes
the Master during the next cycle. During each cycle, the units operate according to the above
lead/lag logic.
3.4 Air Cooled DX with Chilled Water Plus
Summary of Equipment
The primary system shall be Chilled Water Cooling. Direct Expansion Cooling shall be setup as a
back up to the Chilled Water system. Both systems are designed to work independent of each
other.
The Chilled Water System comes standard with a three (3) way water modulating valve, coil, and
an optional “no water flow switch”. The DX system is equipped with a DX coil, compressor(s), and
outdoor air cooled condenser. Optional heaters and humidifiers are also available if needed.
A unique feature of Air Cooled/Chilled Water Plus units is that the chilled water coil is located at
the side of the direct expansion coil. The auxiliary chilled water coil is custom sized so that it
provides identical cooling capacity obtained during the refrigeration cycle with the compressor
operating.
Cooling-Chilled Water
Chilled Water cooling is the primary cooling system for C+ units. For optimum performance, the
controller is programmed to call chilled water cooling for the first 300 seconds regardless of the
chilled water temperature.
The C+ unit can switch over from one cooling mode to another based on sensing Chilled Water
flow or Chilled Water temperature. The standard practice is to sense the Chilled Water flow for
switching.
If “No Water flow”switch is selected, the unit senses the flow of chilled water by using a pressure
differential switch and switches over to DX cooling based on loss of water flow. When no water
flow switch is selected for switch over, the unit will only work on either DX or C.W. cooling mode.

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If chilled water supply temperature is selected for switch over, than the unit shall continue with
chilled water cooling if the chilled water supply temperature is below the required temperature
setpoint and switch over to the DX cooling.

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Cooling-Direct Expansion
Direct Expansion Cooling is designed to operate when the water flow switch senses that there is
no water flow. A digital signal is sent to the system from the controller to modulate the three (3)
way valve to cut water flow to the chilled water coil and the backup system direct expansion
cooling should start. The controller signals the compressor to start cooling. The outdoor
condenser gets energized as needed.
3.5 Air Side Economizer
Summary of Equipment
The Economizer Mixing Box is factory provided; however, it might be installed in the field by
others.
Sequence of Operation
The evaporator fan and a set of dampers for the economizers are energized depending on heating
or cooling demands. The controller commands the economizer box to bring either the minimum
amount of outside air or only outside air based on outside air temperature and humidity. The
controller determines whether the outdoor air temperature and humidity is suitable for
“economizer-cooling”. If the outdoor air is suitable, mechanical cooling shall be locked out by the
outdoor enthalpy control. The set of economizer damper actuators shall be energized, operating
the outdoor air and the return air dampers. The economizer damper actuators shall be regulated
to maintain proper discharge air temperature. When outdoor air is not suitable for “economizer-
cooling”, the Economizer shall be locked out and the outdoor air damper shall maintain minimum
position while the indoor fan is operating. Upon unit shutting down or power loss, the spring
return motor actuator shall close the outdoor air damper. The economizer shall be automatically
locked out during the heat mode (if applicable).
The Air Side Economizer box shall include: prewired modulating spring return damper actuators,
economizer control logic with compressor assist option, minimum outside air damper position
control, economizer control sensors including outdoor air temperature and humidity (enthalpy)
sensor, supply air and/or mixed air sensors. The supply air temperature sensor is used to maintain
the desire supply air temperature using DX and Economizer cooling together. The exhaust of
room air during economizer cooling mode shall be done by others in the field.
3.6 Water Side Economizer Energy miser (EM) Unit Using 2-Way Valves
Summary of Equipment
Energy Miser units are provided with Dual Cooling options. DX cooling using Compressor based
system and Economizer cooling using Water Side Economizer Coil.
The primary system shall be Direct Expansion Cooling. The free cooling Energy Miser coil is
provided together with the DX cooling coil. If the Water temperature drops below the Energy
Miser setpoint, the condenser water is diverted to the free cooling coil and DX cooling will be
programmed to either turned off or made available to assist based on demand.

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The Energy Miser System shall be provided with a Two (2) way water regulating valve for
condenser coil, a Two (2) way modulating chilled water valve for energy miser coil, DX coil(s),
compressor(s) and co-axial water condenser(s). The water valves on water cooled condensers and
free cooling energy miser CW Valves will allow the water flow in either condenser coil or free
cooling EM coil. The two way control valve shall control the amount of flow to auxiliary energy
miser cooling coils to meet the demand when in EM cooling mode. The Two way water regulating
valve will control the amount of water flow in condenser based on the refrigerant pressure in DX
cooling mode. System shall be programmed to do either DX cooling or EM cooling based on
entering water temperature.
Energy Miser systems are connected to Cooling Tower or Dry Fluid Coolers to obtain re-circulating
water or water glycol solution. In addition, the system is equipped with steam generating
humidifier, electric reheat and microprocessor based controller.
A unique feature of Energy Miser system is that the free cooling water coil is located just before
the direct expansion coil and is properly sized to provide the same cooling capacity as the DX
system at 45 deg. F. entering water temperature. The indoor unit will send a signal to enable and
disable the outdoor auxiliary equipment. The outdoor equipment has its own control logic to
provide water temperature suitable for either EM mode or DX cooling mode.
Cooling-Direct Expansion
Direct Expansion Cooling shall operate when the water temperature increases above the specified
EM setpoint. A digital signal is sent to the system by microprocessor to signal the compressors
and the two (2) way valves will regulate the water flow into the water cooled condensers based
on the refrigerant pressure. Each compressor system shall have separate 2-Way water regulating
valves. The Energy miser mode depends on the entering water temperature and it is adjustable.
Cooling-Energy Miser Mode
The unit can switch over from DX cooling mode to free cooling Energy Miser mode based on the
Entering Water temperature.
Unit shall start in DX cooling mode. If the temperature of water supply drops below the setpoint
for the Energy Miser mode, the unit will switch over to the Energy Miser free cooling mode. The
outdoor fluid cooler shall be provided with Energy Miser control panel to maintain lower fluid
temperature during Energy Miser mode.
In the free cooling Energy Miser mode, the compressors will remain shut off while the fans of the
unit shall be on. Humidification and Dehumidification modes shall operate as needed.
3.7 Water Cooled Energy Miser
Summary of Equipment

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Energy Miser units are provided with Dual Cooling options. DX cooling using Compressor based
system and Economizer cooling using Water Side Economizer Coil.
The primary system shall be Direct Expansion Cooling. The free cooling Energy Miser coil is
provided together with the DX cooling coil. If the water temperature drops below the Energy
Miser setpoint, the condenser water is diverted to the free cooling coil and DX cooling will be
programmed to either turned off or made available to assist based on demand.
The Energy Miser System shall come standard with a three (3) way water regulating valve for
condenser coil, a three (3) way modulating chilled water valve for Energy Miser coil, DX coil(s),
compressor(s) and co-axial water condenser(s). The water valves on water cooled condensers and
free cooling Energy Miser CW Valves are three way mixing type designed to divert the flow in
either condenser coil or free cooling EM coil. Three (3) way is used to maintain pressure drop, as
constant GPM is required for free cooling systems. The (3) three way control valve shall control
the amount of flow to auxiliary energy miser cooling coils and maintain constant temperature and
relative humidity
Energy miser systems are connected to Cooling Tower or Dry Fluid Coolers to obtain re-circulating
water or water glycol solution. In addition, the system is equipped with steam generating
humidifier, electric reheat and microprocessor based controller.
A unique feature of Energy Miser system is that the free cooling water coil is located just before
the direct expansion coil and is properly sized to provide the same cooling capacity as the DX
system at 45°F entering water temperature.
Cooling-Direct Expansion
Direct Expansion Cooling shall operate when the water temperature increases above the specified
setpoint. A digital signal is sent to the system by microprocessor to signal the three (3) way valve
to divert the water flow from the free cooling coil to the water cooled condensers and the direct
expansion cooling mode shall start. The microprocessor shall signal the compressor to start
cooling and at the same time energize the water regulating valve to supply water flow to the co-
axial condenser. The Energy Miser mode depends on the entering water temperature and it is
adjustable.
Note: Continuous water shall be flowing through the chilled water valve and will only supply
water to coil when called upon.

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Cooling-Energy Miser Mode
The unit can switch over from DX cooling mode to free cooling Energy Miser mode based on the
entering water temperature.
Unit shall start in DX cooling mode. If the temperature of water supply drops below the setpoint
for the Energy miser mode, the unit will switch over to the Energy Miser free cooling mode. The
controller will send signal to the auxiliary equipment to run Energy Miser mode for fluid
temperature control. The outdoor fluid cooler shall be provided with Energy Miser control panel
to maintain lower fluid temperature during Energy Miser mode.
In the free cooling Energy Miser mode, the compressors may shut off while the fans of the unit
shall be on. Humidification and Dehumidification modes shall be operating as needed. The
Compressors can be locked to remain off during Energy Miser mode if necessary.
3.8 Dry Fluid Cooler with Energy Miser
Summary of Equipment
DRY FLUID COOLER (DFC): The Dry Fluid Cooler Shall Consist of Casing, Coil, Direct-drive Propeller
Fan(s) driven by individual Fan Motor(s), Fan Guard and Mounting Legs. All fan motors shall be
factory wired to a common electrical control box. The Dry Fluid Cooler shall be arranged for
Vertical Air Flow.
The Glycol Coil shall have aluminum fins bonded to copper tubes and shall have full collars that
completely cover the copper tubes. The coil shall be pressure tested to 350 psig and shall be
designed for counter flow for high heat transfer efficiency.
The Dry Fluid Cooler casing shall be made from a non-corrosive metal to minimize maintenance.
Adjustable mounting legs and supports shall be furnished with the DFC. Vibration isolators of the
rubber and shear or spring type are to be field provided by others.
The motors shall be permanently lubricated, sealed ball bearings, with inherent overload
protection. Motors shall be mounted inside the Dry Fluid Cooler Casing for weather protection.
The direct drive fan blades shall be aluminum, and shall be protected by a heavy gauge, steel
wire, zinc plated, and epoxy coated fan guard. Full width baffles to prevent bypass air shall
separate each fan section.
Dry Fluid Cooler (DFC) requires separate power supply and one set of dry contact from indoor unit
to Enable/Disable.
DFC is equipped with its own control panel that includes power block, fan contactors, aqua stats,
freeze stats, relays and single or dual pump package control as necessary.
Aqua stats are installed in the control panel and bulbs to be attached with leaving water header of
the coil.

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The fluid cooler shall be provided with ambient T-stats to control the water temperature during
DX cooling mode. The DFC shall bypass the T-Stat control logic and run all fans continuously
during Energy Miser mode.
Condenser cooling mode
If the water temperature is above 50Deg. F. (Default setting), the DFC will be in normal condenser
cooling mode. Aqua stat # 1 will be open above 50 Deg. F. In normal cooling mode, the DFC will be
enabled by either of the compressor from indoor unit.
The Freeze stat is installed in series of the enabling signal. If the freeze stat opens, the DFC unit
will be fully disabled.
1. The first fan of DFC runs continuously as long as enabling signal is present.
2. The default setting for second fan to cycle OFF is 60 Deg. F and below with aqua
stat #.
3. The default setting for third fan to cycle OFF is 70 Deg. F. and below with aqua
stat #.
4. The default setting for forth fan to cycle OFF is 75 Deg. F. and below with aqua
stat #.
5. All these default settings are field adjustable to fine tune the unit operation.
Energy Miser cooling mode
During winter months, when water temperature drops below 50Deg. F., the aqua stat #1 will
close and DFC unit will switch over to free cooling energy miser mode. In Energy Miser mode, all
other aqua stats (aqua stat 2, 3 and 4) will be bypassed and all fans will run continuously. The free
cooling temperature setpoint on aqua stat #1 must synchronize with Energy Miser water
temperature setpoint for indoor unit.
Pumps
Summary of Equipment
PUMP PACKAGE: The pump package shall include a close coupled, industrial duty pump with
heavy-duty ball bearings motors, stainless steel shafts and bronze fitted construction. The pump
package shall include pump starter, aqua-stats, and fan cycling contactor(s) to control the
condenser glycol temperature. The control panel shall be factory provided for filed installation in
a weatherproof box provided on the Dry Fluid Cooler. The pump shall be protected with a base
and weather shield from the ambient conditions.
DUAL PUMP PACKAGE (Optional): The dual pump package shall include close-coupled, industrial
duty pumps with heavy-duty ball bearings motors, stainless steel shafts and bronze fitted
construction. The pump package shall include pump starters, aqua-stats, and fan cycling
contactor(s) to control the condenser glycol temperature. The control panel shall be factory
provided for filed installation in a weatherproof box provided on the Dry Fluid Cooler. The pumps

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shall be protected with a base and complete vented weather enclosure from the ambient
conditions. The optional Pressure Differential (No Water Flow) switch shall be provided for field
installation.
GLYCOL PUMP: A matching centrifugal circulating pump is provided for field mounting and piping.
Pump Operation
When compressor is on, the pump and fluid cooler will be enabled. Note that this is in DX cooling.
In free cooling, the logic is the same, as pumps are enabled with economizer cooling.
3.9 Special Pump and Dry Fluid Cooler control logic
Pump speed adjusted based on differential pressure across pumps as 2-way control valves modulate.
Dry cooler and Pump controller Sequence of operation
Free cooling mode
Either outdoor air temperature is monitored or a signal from each CRAC unit (free cooling and DX
condenser) is sent to the pump controller to determine which function is provided.
Fan speed may be increased sufficiently to allow pump minimum operating speed to be maintained
should zone loads decrease, thus decreasing flow below safe pump operation.
Outside air temperature reaches 48 deg. F.
Pump controls switch to free cooling mode –Fans run 100% until condenser outlet temperature reaches
38 deg. F., at which time fans speed will reduce to maintain 38 deg. F. or minimum pumps speed is
reached, then fans will reduce speed to maintain minimum pump speed, which is accomplished by 2-
way valves modulating open is response to increased condenser water supply temperature.
Controls shall monitor both fan KW and Pump KW energy consumption and determine best speed
combination to maintain lowest condenser supply water temperature during free cooling mode.
DX Cooling mode
Outside air temperature 50 deg. F.
Pump control increases fan speed as condenser water temperature increases. Maintain 65F condenser
outlet water by modulating fan speed. At 75 deg. F. exiting condenser water temperature fan speed is
100%.
Controls shall monitor both fan KW and Pump KW energy consumption and determine best speed
combination to maintain lowest condenser supply water temperature during DX cooling mode.

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3.10 Optional features
•Discharge air temperature sensor to prevent overheating or cooling of the air stream.
•Outside air temperature sensor for automatic temperature adjustment or economizer
action.
•Free-cooling temperature sensor for water cooled systems.
•Hot gas bypass either by solenoid or by modulating electronic valve.
•Redundant system operation of two or more units with automatic crossover and
compensation.
•Networking to a central command computer, or to an existing building automation system.
The System 2500 is truly one of the most powerful and flexible controllers available for HVAC
units today.
4.0 CONFIGURATION
The display unit is pre-configured at the factory for the most common user requirements. Some
settings can be changed to adapt to the user’s specific needs.
4.1 Software version
Software version: During boot-up, the splash screen is shown briefly with a quick summary of the
loaded operation system along with software, boot, and O/S version. The about screen can also
be accessed via the menu. Version number is needed prior to contacting the factory for technical
support.
Figure 2 Software information