McQuay WGS Installation Manual
Operation & Maintenance Data
Group: WSHP
Part Number: 910127707
Date: June 2012
OM 1149
MicroTech® III SmartSource Unit Controller with I/O Expansion Module for
Single and Two Stage Water Source Heat Pump Units, Models GS/GT
I/O Expansion Module
MicroTech III SmartSource Unit Controller
©2012 McQuay International
Contents
Introduction ..........................................................................3
Control Boards Terminals and Connectors Descriptions 4
MicroTech III Unit Controller .............................................4
I/O Expansion Module .....................................................5
BACnet Communication Module.......................................5
LonWorks Communication Module .................................5
Replacing a MicroTech III Circuit Board: ........................... 7
Initial Power-Up ...................................................................7
General Use and Information .............................................8
Operating Modes ..............................................................8
Control Inputs (HP, LP, SLTS, COF, U, E, O) .................. 10
Control Outputs {A and IV/PR (H8)}................................10
Unoccupied Operation – Stand Alone Thermostat Control 11
Thermostat Inputs (G, Y1, Y2, W1, and W2) .................. 11
Additional Fault Modes ..................................................... 11
High / Low Pressure Faults (HP/LP) ...............................12
Fan Operation During Most Modes, Faults and
Shutdowns .........................................................................14
Faults and Modes ...........................................................14
Troubleshooting the Water Source Heat Pump Unit ......16
Microtech® III Unit Controller Interface to External
Equipment ..........................................................................17
Appendix A .........................................................................17
Operation and Maintenance of I/O Expansion Module ...17
Introduction .....................................................................17
Initial Power up ..................................................................17
Operation ............................................................................18
Thermostat Inputs ...........................................................18
Electric Heat Controls .......................................................18
Supplemental Electric Heat Control ................................18
Boilerless Heat Control ...................................................18
Compressor Heating Source Selection ...........................19
Fan Speed Control .............................................................19
I/O Expansion Module Faults and Fan Operating Modes
Tables .................................................................................20
Unit Options: ......................................................................21
Waterside Economizer ....................................................21
SmartSource Dehumidication ........................................21
Hot Gas Reheat Smart Dehumidication ........................21
Simplied Dehumidication.............................................22
Humidistat Controlled Dehumidication ..........................22
Dehumidication Only: ....................................................24
MicroTech III Unit Controller with LonWorks®
Communication Module ..................................................25
MicroTech III Controller with an Optional BACnet®
Communication Module ..................................................26
Appendix C – Typical Wiring Diagrams ......................27-35
115V, 1Ph – Model WGS, MicroTech III SmartSource Unit
Controller with BACnet Communication Module
(Hot Gas Reheat) (See page 28 for Service & Disconnect
Wiring) ............................................................................27
265V, 1Ph – Model WGS-WGT, MicroTech III SmartSource
Unit Controller with BACnet Communication Module (Hot
Gas Reheat) (See page 30 for Service & Disconnect
Wiring) ............................................................................29
208-230V, 1Ph – Model WGS-WGT, MicroTech III
SmartSource Unit Controller with BACnet Communication
Module (Waterside Economizer, Desuperheater, 115V Loop
Pumps & 20kW Electric Heat) (See page 32 for Service &
Disconnect Wiring)..........................................................31
208-230V, 3Ph – Model WGS-WGT, MicroTech III
SmartSource Unit Controller with BACnet Communication
Module (Waterside Economizer, 230V Loop Pumps &
5kW Electric Heat) (See page 34 for Service & Disconnect
Wiring) ............................................................................33
460V, 3Ph – Model WGS-WGT, MicroTech III SmartSource
Unit Controller with BACnet Communication Module
(Waterside Economizer, 230V Loop Pumps & 20kW
Electric Heat) (See page 36 for Service & Disconnect
Wiring) ............................................................................35
Controller Comparison ....................................................37
Introduction
This installation and operation manual covers the MicroTech® III unit controller for Daikin McQuay G-Series Water
Source Heat Pumps. For information on LonWorks® or
BACnet® communication modules and other ancillary components, see:
■ IM 927 - MicroTech III Water Source Heat Pump
LonWorks Communication Module.
■ IM 928 - MicroTech III Water Source Heat Pump Unit
Controller BACnet MS/TP Communication Module.
■ IM 933 - LonWorks Plug-In Software for use
with MicroTech III Unit Controller - LonWorks
Communication Module.
■ IM 952 - Multiple Unit Control Panel (MUCP) for use
with MicroTech III Unit Controller and Mark IV Unit
Controller.
■ IM 955 - MicroTech III Water Source Heat Pump Wall-
Mounted Room Temperature Sensors.
■ IM 956 - Temperature Sensors for Units with MicroTech
III Unit Controller and LonWorks Communication
Module.
OM 1149 / Page 3 of 40
Control Boards Terminals and Connectors Descriptions
MicroTech III Unit Controller
Table 1: MicroTech III Unit Controller Terminals &
Descriptions
H1 – 1 24 24 VAC Power Input
H1 – 2 C 24 VAC common
H2 – 1 SL1 Fan Main Required Output – Switched L1
H2 – 2 Blank Terminal
H2 – 3 N Fan Main Required Output – Neutral
H3 – 1 HP1-1 Comp High Pressure Switch (HP1) Input Terminal 1
H3 – 2 HP1-2 Comp High Pressure Switch (HP1) Input Terminal 2
H4 – 1 1 Discharge Air Temp Sensor – Common
H4 – 2 Discharge Air Temp Sensor – Signal
H4 – 3 Leaving Water Temp Sensor – Common
H4 – 4 Leaving Water Temp Sensor – Signal
H5 – 1 1
H5 – 2
H5 – 3
H5 – 4
H5 – 5
H5 – 6
H5 – 7
H5 – 8
H5 – 9
H5 – 10
H5 – 11
H5 – 12
H6 – 1 1 Condensate Overow Signal Input
H6 – 2 Compressor Suction Temp Sensor (LT1) – Common
H6 – 3 Compressor Suction Temp Sensor (LT1) – Signal
H6 – 4 Compressor Low Pressure Switch (LP1) – Source Voltage
H6 – 5 Compressor Low Pressure Switch (LP1) – Signal
H6 – 6 Reversing Valve – Common
H6 – 7 Reversing Valve – Output
H7 – 1 1 No Connection
H7 – 2 No Connection
Connections to I/O Expansion Board
H7 – 3 Red LED Output
H7 – 4 Green LED Output
H7 – 5 Yellow LED Output
H7 – 6 Red-Green-Yellow LED Common
H8 – 1 1 Isolation Valve/Pump Request Relay N/O
H8 – 2 Isolation Valve/Pump Request Relay N/C
H8 – 3 24 VAC Common
H9 – 1 1 Room Temp Sensor & Tenant Override – Signal
H9 – 2 Room Temp Sensor & Tenant Override – Common
TB1 – 1 1 Room Sensor – Status LED Output
TB1 – 2 2 Room Sensor – Fan Mode & Unit Mode Switches
TB1 – 3 3 Room Sensor – Setpoint Adjust Potentiometer
TB1 – 4 4 Room Sensor – Room Temp Sensor & Tenant Override
TB1 – 5 5 Room Sensor – DC Signal Common
TB2 – 1 R 24 VAC
TB2 – 2 A Thermostat – Alarm Output
TB2 – 3 W2 Thermostat – Heat Stage #2 (W2) Input
TB2 – 4 W1 Thermostat – Heat Stage #1 (W1) Input
TB2 – 5 Y2 Thermostat – Cool Stage #2 (Y2) Input
TB2 – 6 Y1 Thermostat – Cool Stage #1 (Y1) Input
TB2 – 7 G Thermostat – Fan Input
TB2 – 8 O Thermostat – Heat Stage #3 (W3) Input
TB2 – 9 C 24 VAC Common
TB3 – 1 E Emergency Shutdown Input
TB3 – 2 U Unoccupied Input
L1 – 1 L1 - 1 Line Voltage Terminal 1
L1 – 2 L1 - 2 Line Voltage Terminal 2
L1 – 3 L1 - 3 Line Voltage Terminal 3
N1 N1 Neutral Terminal 1
N2 N2 Neutral Terminal 2
N3 N3 Neutral Terminal 3
Page 4 of 40 / OM 1149
I/O Expansion Module
Table 2: I/O Expansion Module Connectors/Terminals
H1 – 1 1
H1 – 2
H1 – 3
H1 – 4
H1 – 5
H1 – 6
H1 – 7
H1 – 8
H1 – 9
H1 – 10
H1 – 11
H1 – 12
H2 – 1 1 Auxiliary Heat Stage #2 Output – N/O
H2 – 2 No Connection
H2 – 3 24 VAC Common
H3 – 1 1 Ext. 24 VAC In
H3 – 2 Ext. 24 VAC Common In
H3 – 3 HGR / Waterside Economizer Output – N/O
H3 – 4 Ext. 24 VAC Common
H3 – 5 ECM Fan Motor Variable Speed Signal Output
H3 – 6 ECM Fan Motor Variable Speed Signal – Common
H4 – 1 1 Entering Water Temp Sensor – Signal
H4 – 2 Entering Water Temp Sensor – Common
H5 – 1 1 No Connection
H5 – 2 No Connection
H5 – 3 Red LED Output
H5 – 4 Green LED Output
H5 – 5 Yellow LED Output
H5 – 6 Red-Green-Yellow LED Common
H6 – 1 HP2-1 Comp High Capacity High Press Sw (HP2) Input Terminal 1
H6 – 2 HP2-2 Comp High Capacity High Press Sw (HP2) Input Terminal 2
H7 – 1 Fan Speed Table Row Select – Signal
H7 – 2 Fan Speed Table Row Select – Common
H7 – 3 Thermostat – Heat Stage #4 (W4) Input – Signal
H7 – 4 Auxiliary 24 VAC Out
H8 – 1 1 Compressor – High Capacity Output – N/O
H8 – 2 24 VAC Common
H8 – 3 No Connection
H8 – 4 Auxiliary Heat Stage #1 Output – N/O
H8 – 5 24 VAC Common
TB1 – 1 1 Humidistat Signal Input
TB1 – 2 2 Thermostat - Heat Stage #4 (W4) Input – Signal
Connections to Main Board
BACnet Communication Module
Table 3: BACnet Communication Module Connectors/
Terminals
P4 – 1 P4 GND
P4 – 2 + 5 VDC
P4 – 3 SPI SELECT (SPI Select To Communications Board)
P4 – 4 SPI CLK (Master Clock)
P4 – 5 SPI RCV (MOSI)
P4 – 6 SPI XMIT (MISO)
P4 – 7 SRDY OUT (SPI Ready To Baseboard)
P4 – 8 No Connection
P3 – 1 P3 Network Signal +
P3 – 2 Network Signal –
P3 – 3 REF
P3 – 4 Shield
LonWorks Communication Module
Table 4: LON Communication Module Connectors/
Terminals
CN_SPI – 1 CN_SPI GND
CN_SPI – 2 + 5 VDC
CN_SPI – 3
CN_SPI – 4 SPI_CLK_0 (Master Clock)
CN_SPI – 5 SPI_RX_0 (MOSI)
CN_SPI – 6 SPI_TX_0 (MISO)
CN_SPI – 7 SREADY_0 (SPI Ready To Baseboard)
CN_SPI – 8 No Connection
TB1 – 1 TB1 Network Signal A
TB1 – 2 Network Signal B
TB1 – 3 REF
SPI_SELECT1_0 (SPI Select To CommunicationsBoard)
OM 1149 / Page 5 of 40
Figure 1: MicroTech III Unit Controller & I/O Expansion Module Connectors Descriptions
Page 6 of 40 / OM 1149
CAUTION
Initial Power-Up
The MicroTech III circuit board incorporates static sensitive de-
vices. A static charge from touching the device can damage the
electronic components. To help prevent damage during service,
use static discharge wrist straps.Static discharge wrist straps
are grounded to the heat pump chassis through a 1 Mohm resistor.
Pre start check list:
A random start delay time between 180 and 240 seconds is
generated at power up.
Figure 2: Location of Configuration Jumpers on the Base
Board Controller
Replacing a MicroTech III Circuit Board:
1. Connect wrist strap to unit.
2. Remove faulty board and place on static protected surface.
3. Remove replacement board from static protected bag.
Do not touch circuit board; hold by edges.
4. Holding board in grounded hand, install board in unit.
5. Insert faulty board in empty static bag for return.
Table 5: Configuration Jumper Settings
Jumper Description Options
JP1 Mode
Shorted for service/test operation mode
JP2 Fan operation only applies to Open for continuous fan operation
room sensor control without a Shorted for cycling fan operation
fan mode On/Auto switch
JP3 Freeze protection
Shorted for antifreeze protection
JP4 Freeze fault protection Open for none
Shorted to enable freeze fault protection based on Leaving Water Temperature (LWT)
JP5 Set point adjustment range only Open for adjustment range of -5.0° to +5.0° F
applies to network controls with a Shorted for 55° to 95° F adjustment range
room temperature sensor
JP6 Room control type
Shorted for room temperature sensor control, MicroTech III only
JP7 Compressor heating source Open to enable compressor heating
Shorted to disable compressor heating
JP8 I/O expansion module Open when I/O expansion module is not needed
Shorted when I/O expansion module is required
Open for normal operation mode
Open for water freeze protection
Open for thermostatic room control
OM 1149 / Page 7 of 40
General Use and Information
The Microtech III SmartSource unit controller is a water
source heat pump control platform used to control the heat
pump in all modes of operation, including variable speed
fans, two stage compressors, loop pumps, economizers,
reversing valves, and all components used to control conditioned space temperature and humidity. By adding communi-
cations cards, (LonWorks or BACnet) network integration is
possible. The controller can be used with thermostat control
or wall sensor control.
All MicroTech III unit controller inputs must be operated by
dry contacts powered by the control board’s power terminals.
No solid state devices (Triacs) may be used to operate MicroTech III unit controller inputs. No outside power sources may
be used to operate MicroTech III. All units must be properly
grounded per local code requirements. See the Installation
and Maintenance bulletin specic to your Water Source Heat
Pump.
Occupied Operation
The board will be in occupied mode if the unoccupied termi-
nal (U) is not shorted to ground.
Yellow Green Red
Off On Off
Operating Modes
■ Start-up – The unit will not operate until all the inputs
and safety controls are checked for normal conditions.
■ Cooling mode – On an initial call for cooling, the fan
will energize at its “fan only” setting, the pump request
will engergize, the 45 second ow timer will start after
the ow, compressor minimum off, and random startup
timers are expired, the compressor and fan will start at the
stage 1 cooling settings. If room setpoint conditions are
not satised, the fan will operate at the stage 2 cooling
settings. When the room setpoint conditions are satised,
the compressor will shut off and the fan will operate
according to its “fan only” setting when enabled for
continuous fan operation. If fan cycling is enabled, the fan
will turn off once room setpoint conditions are satised.
■ Dehumidication modes – There are four
dehumidication modes of operation;
1. Smart Dehumidication with Hot Gas Reheat
2. Simplied Dehumidication
3. Humidistat Controlled Dehumidication
4. Dehumidication Only
See "SmartSource Dehumidication" on page 21 for details.
▪ Smart Dehumidication – Uses hot gas reheat,
a humidistat, a 2-stage thermostat and air ow
management for precise humidity control. When the
cooling and heating temperature setpoint is satised
and there is a call for dehumidication, maximum
dehumidication is initiated by energizing the
fan at its “fan only” setting, energizing the pump
Board LED Status – Occupied
request, engergizing the 30 second proof-of-ow
timer, energizing the hot gas reheat solenoid valve,
energizing the compressor at maximum cooling, and
energizing the fan at the dehumidication setting.
When the room humidity conditions are satised,
the compressor will shut off and the fan will operate
according to its “fan only” setting when enabled for
continuous fan operation. If fan cycling is enabled, the
fan will turn off, once room humidity conditions are
satised.
▪ Simplied Dehumidication – Uses a 3-stage
thermostat and air ow management to optimize unit
capacity and fan speed for maximum latent capacity
while decreasing room humidity levels. On a call for
cooling, the fan will energize at its “fan only” setting,
the pump request will energize, the 30 second ow
timer will start, after the ow, compressor minimum
off, and random startup timers are expired, the
compressor will start at stage 1 cooling and the fan
will energize at its dehumidication setting. If the
room setpoint temperature is still not satised, the fan
will be energized at the stage 1 cooling settings. If
the room setpoint temperature is still not satised, the
compressor and fan will operate at the stage 2 cooling
settings. When the room temperature conditions are
satised, the compressor will shut off and the fan
will operate according to its “fan only” setting when
enabled for continuous fan operation. If fan cycling
is enabled, the fan will turn off, once room setpoint
conditions are satised.
▪ Humidistat Controlled Dehumidication – Uses
a humidistat and 2-stage thermostat to control room
humidity levels. On a call for dehumidication, the
fan will energize at its “fan only” setting, the pump
request will energize, the 30 second ow timer will
start, after the ow, compressor minimum off, and
random startup timers are expired, the compressor
will start at stage 1 cooling and the fan will energize
at its dehumidication setting. If the room setpoint
temperature is not satised, the fan will be energized
at the stage 1 cooling settings. If the room setpoint
temperature is still not satised, the compressor and
fan will operate at the stage 2 cooling settings. When
the room temperature and humidity conditions are
satised, the compressor will shut off and the fan
will operate according to its “fan only” setting when
enabled for continuous fan operation. If fan cycling
is enabled, the fan will turn off once room setpoint
conditions are satised.
▪ Dehumidication Only – Uses a humidistat in the
cooling only mode. On a call for dehumidication, the
fan will energize at its “fan only” setting, the pump
request will energize, the 30 second ow timer will
start, after the ow, compressor minimum off, and
random startup timers are expired, the compressor
will start at stage 1 cooling and the fan will energize
Page 8 of 40 / OM 1149
at its dehumidication setting. Room temperature
conditions are not monitored or maintained. The unit
only responds to a call for dehumidication. When the
room humidity conditions are satised, the compressor
will shut off and the fan will operate according to its
“fan only” setting when enabled for continuous fan
operation. If fan cycling is enabled, the fan will turn
off once room setpoint conditions are satised.
■ Heating mode – On an initial call for heating, the fan will
energize at its "fan only" setting, the pump request
will energize, the 30 second ow timer will start,
after the ow, compressor minimum off, and random
startup timers are expired, the compressor and fan will
start at stage 1 heating settings; the reversing valve
shall energize 5 seconds after the compressor turns
on. If room setpoint conditions are not satised, the
fan will operate at stage 2 heating settings. When the
room setpoint conditions are satised, the compressor
will shut off and the fan will operate according to its
“fan only” setting when enabled for continuous fan
operation. If fan cycling is enabled, the fan will turn
off, once room setpoint conditions are satised.
■ Boilerless Electric Heat mode – When the entering water
temperature is below setpoint, the compressor will not
be allowed to operate. On an initial call for heating,
stage 1 electric heat will be energized and the fan will
start at its electric heat setting. For units equipped with
2 stages of electric heat, if room setpoint conditions
are not satised, the second stage of electric heat
will be energized and the fan will continue to operate
at its electric heat setting. When the room setpoint
conditions are satised, electric heat will be de-
energized and the fan will continue to operate at its
“fan only” setting when enabled, for continuous fan
operation. If fan cycling is enabled, the fan will turn
off after 30 seconds once room setpoint conditions are
satised.
■ Supplemental Electric Heat mode – On an initial call
for heating, the fan will energize at its “fan only”
setting, the pump request will energize, the 30 second
ow timer will start. After the ow, compressor
minimum off, and random startup timers are expired,
the compressor and fan will start at stage 1 heating
settings; the reversing valve shall energize 5 seconds
after the compressor turns on. If room setpoint
conditions are not satised, the fan will operate at
stage 2 heating settings. If room setpoint conditions
are still not satised, the compressor will continue
to operate and stage 1 electric heat will be energized
and the fan will operate at its electric heat setting. For
units equipped with 2 stages of electric heat, if room
setpoint conditions are still not satised, the second
stage of electric heat will be energized and the fan will
continue to operate at its electric heat setting. When
the room setpoint conditions are satised, electric
heat will be de-energized allowing the compressor
to remain on if necessary to maintain room setpoint
conditions. The fan will operate according to its
“fan only” setting when enabled, for continuous fan
operation. If fan cycling is enabled, the fan will turn
off once room setpoint conditions are satised.
■ Primary Electric Heat mode – On an initial call for
heating, stage 1 electric heat will be energized and
the fan will start at its electric heat setting. For units
equipped with 2 stages of electric heat, if room
setpoint conditions are not satised, the second stage
of electric heat will be energized and the fan will
continue to operate at its electric heat setting. When
the room setpoint conditions are satised, electric
heat will be de-energized and the fan will continue
to operate at its “fan only” setting when enabled, for
continuous fan operation. If fan cycling is enabled, the
fan will turn off after 30 seconds once room setpoint
conditions are satised.
■ Emergency Electric Heat mode – A 24v control signal
from the thermostat will initiate a call for stage 1 or stage
2 electric heat. The compressor will not operate and the
fan will start at its electric heat setting.
■ Occupied Mode – The MicroTech III SmartSource unit
controller will manage occupied and unoccupied modes
of operation. The occupancy mode can be established by
a BACnet or LonWorks communication signal, from a
room sensor equipped with “Occupied/Unoccupied” mode
functions, or a thermostat equipped with an “Occupied/
Unoccupied” mode switch. When in the occupied
mode, the unit will be controlled to its occupied setpoint
conditions. The occupancy state will be displayed on
sensors equipped with “Occupied/Unoccupied” mode
functions and annunciation capabilities.
■ Unoccupied Mode – When operating in the unoccupied
mode, the unit will be controlled to its unoccupied setpoint
conditions and the fan will cycle according to a call for
cooling, dehumidication or heating. A simple “grounded”
signal between terminals U and C on the MicroTech
III SmartSource unit controller will place the unit into
the unoccupied mode for night setback operation. The
occupancy state will be displayed on sensors equipped
with “Occupied/Unoccupied” mode functions and
annunciation capabilities.
■ Override Mode – A momentary (4 to 9 seconds) press of
the “Override” button on the thermostat or room sensor
during the unoccupied mode will cause the unit to operate
in the occupied mode for two hours, for after-hours
heating, cooling or dehumidication. “OVERRIDE” will
be displayed on sensors equipped with override button and
annunciation capabilities.
OM 1149 / Page 9 of 40
■ “Energy Save” Bypass Mode – BACnet or LonWorks
units can receive a signal from the Building Automation
System (BAS) to initiate the energy savings mode. This
mode is typically initiated by the BAS with smart grid
technologies to save energy. The savings is driven by
reducing peak electrical demand for the building. Once
initiated, the MicroTech III SmartSource unit controller
will reset its effective setpoint to minimize the stage
of compressor operation. “E-SAVE” will be displayed
on sensors equipped with bypass mode annunciation
capabilities.
■ Motorized Water Valve or Pump Start – When there
is a call for cooling, dehumidication or heating, the
MicroTech III SmartSource unit controller will energize
its IV/PR (H8) terminal to open the motorized water
valve or start the loop pump 30 seconds prior to starting
the compressor. The IV/ PR (H8) terminal may be “daisy
chained” between 200 units.
Control Inputs (HP, LP, SLTS, COF, U, E, O)
The control inputs are High Pressure (HP), Low Pressure
(LP), Suction Line Temperature Sensor (SLTS), Condensate
Overow (COF), Unoccupied (U), and Remote Shutdown
(E). The control inputs are in normal states during occupied
mode. The state of each control in occupied mode during
normal operation is as follows:
■ High Pressure (HP): Normally closed switch that opens
on a high refrigerant pressure condition. Control will
generate a high pressure fault and disables the compressor
output when the switch is open.
■ Low Pressure (LP): Normally closed switch that opens on
a low refrigerant pressure condition. Control will generate
a low pressure fault when the switch is open. Suction Line
Temperature Sensor (SLTS): temperature sensor on the
suction line.
■ Condensate Overow (COF): senses condensate level
in condensate pan. Control will generate a fault when
condensate level is too high.
■ Unoccupied (U): Grounding this terminal puts the control
into unoccupied mode.
■ Remote Shutdown (E): Grounding this terminal forces the
control to shutdown the unit.
Control Outputs {A and IV/PR (H8)}
The control outputs are Alarm Fault (A) and Isolation Valve
/ Pump Request {IV/PR (H8)}. The operation of the control
outputs during occupied mode is as follows:
■ The thermostat alarm output will be energized when there
are fault conditions presently active. Without any fault
conditions active, the alarm output shall be de-energized.
■ Isolation Valve / Pump Request {IV/PR (H8)}: is
selectable to be energized when the compressor is
off (normally closed), or when the compressor is
on (normally open), by moving the wire lead to the
appropriate terminal.
Figure 3: H8 Terminals on MicroTech III Board
■ Reversing Valve: 24V signal that is energized upon a call
for heat mode.
■ Compressor Relay: Line or low voltage output used to
control compressor. (On/Off)
Fan Operation
The G terminal controls continuous fan operation. The fan
runs continuously when the G terminal is energized. When the
G terminal is de-energized, the fan cycles with the compressor.
Cooling Mode
The Y1 terminal controls the Cooling Mode of operation.
When the Y1 terminal is energized (24VAC), the following
occurs:
1. The fan energizes.
2. The IV/PR (H8) control output de-energizes or energizes
depending on the H8 terminal wiring (refer to Table 1 on
page 4 & Figure 1 on page 6).
3. The compressor energizes after 30 seconds.
4. The reversing valve de-energizes 5 seconds after the
compressor turns on.
When the Y1 terminal is de-energized, the following occurs:
1. The compressor de-energizes.
2. The IV/PR (H8) control output energizes or de-energizes
depending on the H8 terminal wiring (refer to Table 1 on
page 4 & Figure 1 on page 6).
3. The fan de-energizes, unless the G terminal is energized
(24VAC).
Note: To prevent compressor cycling and all compressors
from starting up together after loss of power, the
required minimum on/off time default is 180 seconds.
This may cause the compressor time delay to be
longer than indicated above.
Page 10 of 40 / OM 1149
Heating Mode
The W1 terminal controls the occupied Heating Mode of
operation. When the W1 terminal is energized, the following
occurs:
1. The fan energizes.
2. The IV/PR (H8) control output de-energizes or energizes
depending on the H8 terminal wiring (refer to Table 1 on
page 4 & Figure 1 on page 6).
3. The compressor energizes after 30 seconds.
4. The reversing valve energizes 5 seconds after the
compressor turns on.
When the W1 terminal is de-energized, the following occurs:
1. The compressor de-energizes.
2. The IV/PR (H8) control output energizes or de-energizes
depending on H8 terminal wiring (refer to Table 1 on page
4 & Figure 1 on page 6).
3. The fan de-energizes, unless the G terminal is energized.
Note: To prevent compressor cycling, the required minimum
on/off time default is 180 seconds. This may cause
the compressor time delay to be longer than indicated
above.
Unoccupied Operation – Stand Alone Thermostat Control
The board will be in unoccupied mode if the unoccupied
terminal (U) is grounded.
Yellow Green Red
On On Off
Board LED Status – Unoccupied
Thermostat Inputs (G, Y1, Y2, W1, and W2)
The only thermostat inputs used during unoccupied operation
are Y2 and W2, which when energized will activate Cooling
Mode or Heating Mode respectively. Inputs G, Y1 and W1
have no effect during unoccupied mode.
Figure 4: Terminal "U" - Grounded for Unoccupied
Additional Fault Modes
Brownout
Yellow Green Red
Off Flash Off
Brownout condition is provided to protect the water source
heat pump’s motor electrical damage due to low voltage
conditions.
The MicroTech III unit controller is designed to monitor the
24VAC power supply to the board. If the line voltage supplied to the water source heat pump drops, the 24VAC supply
to the control board will also drop. When the line voltage
supplied to the unit drops below approximately 80% of the
unit nameplate rated value, the controller goes into brownout
condition. The controller remains in brownout condition until
line voltage returns to approximately 90% of the unit nameplate value.
When in brownout condition, thermostat and control inputs
have no affect upon unit operation. Remote shutdown and
brownout conditions have the same level of priority. See "Pri-
ority Level of Faults and Modes" on page 14.
When the unit is in brownout condition the following occurs:
1. The compressor de-energizes.
2. The fan de-energizes.
3. Fault terminal (A) energizes (fault). A to R will be used to
indicate an alarm signal.
When the line voltage supplied to the unit returns to accept-
able levels (~90% of nameplate) the controller returns to the
current mode.
Remote Shutdown
Yellow Green Red
Off Flash Off
When the E terminal is grounded, the MicroTech III unit
controller enters remote shutdown mode. Remote shutdown
is provided so that when properly connected to a building
automation system, remote switch, etc., the E terminal can be
used to shut down the water source heat pump.
Figure 5: Terminal "E" - Grounded for Remote Shutdown
Board LED Status – Brownout
Board LED Status – Remote Shutdown
OM 1149 / Page 11 of 40
When in remote shutdown (E terminal grounded), thermostat
and control inputs have no affect upon unit operation. No faults
or modes have higher priority than remote shutdown. Remote
shutdown and brownout condition have the same level of
priority. See "Priority Level of Faults and Modes" on page 14.
When the unit is in remote shutdown mode, the following
occurs:
1. The compressor de-energizes (if enabled).
2. The fan de-energizes (if enabled).
3. Fault terminal (A) will remain de-energizes because
emergency shutdown is a "mode". A to C will be used to
indicate normal operation.
When the E terminal is no longer grounded the unit will automatically return to normal operation.
Note: The remote shutdown input (E) will suspend unit
operation. Disconnect power when servicing the unit/
controller.
High / Low Pressure Faults (HP/LP)
Normally closed high and low refrigerant pressure switches
help protect the water source heat pump from excessively
high or low refrigerant pressures. The MicroTech III unit controller monitors these switches individually. If the compressor
is running and the HP circuit is open, the controller enters
a pressure fault mode. If the LP circuit is open after a time
delay (default of 30 seconds, adjustable if a communication
module is present) the controller enters a low pressure fault
mode.
Yellow Green Red
HP Off Off Flash
LP Off Off Solid
See "Priority Level of Faults and Modes" on page 14..
When the unit is in high or low pressure fault modes the following occurs:
1. The compressor de-energizes.
2. The IV/PR(H8) output will change state. (On to Off / Off
to On).
3. The fan de-energizes.
4. The fault terminal (A) energizes (fault). A to R will be
used to indicate an alarm signal.
High Pressure Reset
After the HP circuit is closed, the unit does not return to
normal operation until the alarm is manually reset. The unit is
locked out in this manner until the unit can be serviced.
The alarm is reset by a short interruption of unit power, by
holding down the tenant override button for more than 10
seconds, or via the Building Automation System (BAS).
Low Pressure Reset
The low pressure switch fault is subject to intelligent reset.
If the pressure recovers, it resets two times within a 24-hour
time period. If further faults are detected within the 24 hours,
the controller must be manually reset as described in the High
Pressure Reset section above.
Board LED Status – High/Low Pressure Faults
Low Suction Temperature Fault Heating
1. The control will attempt to recover from a low suction
temperature condition by defrosting water heat exchanger
(coaxial coil).
2. See the Defrost Process below for details.
Low Suction Temperature Fault Cooling
1. When the suction line temperature falls below 28° F
disable the compressor output only.
2. The fan will continue to run drawing warmer air over the
air heat exchanger.
3. When the suction line temperature increases by Low Temp
Protect Diff (the default is 8° F) degrees.
4. The compressor is available for cooling if the Compressor
Minimum Off timer has expired.
5. Mark the occurrence of the fault.
Yellow Green Red
Flash Off Off
Board LED Status – Low Suction Line Temperature Fault
Defrost Sequence of Operation:
1. Immediately turn off the compressor if operating in the
cooling or dehumidication modes.
2. The fan will remain on at the existing fan speed if the unit
is cooling, dehumidifying or congured for electric heat
3. The reversing valve output is de-activated, placing the
reversing valve in the cooling mode and moving warm
refrigerant to the coax coil.
4. Fan speed is not changed, however “Heat Stage #1” speed
is used if the fan is presently off.
5. If the compressor was on at the beginning of the defrost
process, then start the 60 second xed defrost timer.
6. Wait for the defrost timer to expire.
7. If the alarm condition has cleared:
· Return to normal operation.
8. If the alarm condition remains active:
• Compressor High Capacity is turned off
• Compressor is immediately turned off, ignoring the
Compressor Minimum ON timer
• Compressor is disabled for heating and cooling
• Electric heating can be used if it is available
• Fan and pump remain available for operation
Heating Mode
When the suction line temperature falls below 28°F on standard equipment (6.5°F on Geothermal) the low temperature
fault generates the following:
■ The reversing valve de-energizes. The compressor and fan
continue to operate in cooling mode for 60 seconds, which
results in a defrost mode. This defrosts any ice that may
have accumulated in the water-to-refrigerant coil, because
of a lack of condenser water ow in heat mode.
■ In heat mode the low temperature fault is subject to
Intelligent Reset.
Page 12 of 40 / OM 1149
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