Zonex DigiTract 4-2 User manual

DigiTract 4-2
Two Stage Heat/Cool
Comfort Control System
Installation Guide
Part #DT4MAN
Rev. April 2003
Zoning Systems
That’s all we do.

TABLE OF CONTENTS...................................................................................................................................................................Page
INTRODUCTION.......................................................................................................................................................................................................1
SYSTEM DESCRIPTION...........................................................................................................................................................................................1
COMPONENT SELECTION GUIDE..........................................................................................................................................................................2
WIRING
Gas/Electric DTGE4-2.........................................................................................................................................................................................3
Heat Pump DTHP4-2..........................................................................................................................................................................................4
Zone Dampers....................................................................................................................................................................................................5
SYSTEM CONTROLLERS
Gas/Electric DTGE4-2
Operation...........................................................................................................................................................................................6
Status Lights .......................................................................................................................................................................................6
Components.......................................................................................................................................................................................7
Heat Pump DTHP4-2
Operation...........................................................................................................................................................................................8
Status Lights .......................................................................................................................................................................................9
Components.....................................................................................................................................................................................10
CAPACITY CONTROLLERS.....................................................................................................................................................................................11
Gas/Electric DTGE4-2.......................................................................................................................................................................11
Heat Pump DTHP4-2........................................................................................................................................................................11
Calibration .......................................................................................................................................................................................11
LAS Installation ................................................................................................................................................................................11
ZONE THERMOSTATS
Types ........................................................................................................................................................................................................12
Zonex Systems Gas/Electric Models..................................................................................................................................................................12
Digital (SADIGI)...............................................................................................................................................................................12
Digital (SADIGI) Operation..............................................................................................................................................................13
Programmable (101PROG)..............................................................................................................................................................12
Communicating (DIGICOM/DIGIHP)................................................................................................................................................12
Compatibility ....................................................................................................................................................................................................12
ZONE DAMPERS
Round ...................................................................................................................................................................................................14-15
Rectangular.................................................................................................................................................................................................16-17
Installation Notes..............................................................................................................................................................................................18
BYPASS DAMPERS
Barometric..................................................................................................................................................................................................18-19
Electronic ...................................................................................................................................................................................................20-21
Static Pressure Controller.................................................................................................................................................................22
DAMPER TRANSFORMER .....................................................................................................................................................................................23
SYSTEM STARTUP
Gas/Electric DTGE4-2.......................................................................................................................................................................................23
Heat Pump DTHP4-2........................................................................................................................................................................................24
Troubleshooting / Service Checks.....................................................................................................................................................................25
LAS Voltage – Temperature Conversion Chart..................................................................................................................................................25

1
Fused 24V Transformer
DIGITRACT 4-2
System Controller
73
73
73
73
5
23
1
4
6
ZONE 4
ZONE 3
ZONE 2
ZONE 1
LAS
The Zonex Systems Digitract 4-2 zoning system enables up to four room thermostats to control a single HVAC system. This permits superior building
temperature control over a standard single thermostat. To provide economical, effective and simplified remote control and monitoring capability of
one or more Digitract 4-2 zone control systems, the ZonexCommander may be used to manage up to 80 thermostat schedules. The ZonexCommander is
a Windows®based thermal management system, which can integrate gas/electric and heat pump zone systems to include stand alone HVAC systems.
INTRODUCTION
SYSTEM DESCRIPTION
The DigiTract 4-2 zoning system consists of a 2-stage System Controller
with built-in Capacity Control (leaving air sensor), Zone Dampers, Zone
Thermostats, Bypass Damper and Damper Transformer.
The System Controller is the heart of the Digitract 4-2 zoning system.
It monitors the leaving air temperature, zone thermostats and controls the
HVAC System and zone dampers. See pages 6 to 10 for further information.
The Leaving Air Sensor (LAS) is part of the staging and capacity control
feature of the System Controller. It is a sensor placed in the leaving air
of the HVAC system. The LAS monitors the leaving air temperature of the
HVAC system and sends this information to the System Controller. The
System Controller uses this information to stage and temporarily cycle
the HVAC system off if the leaving air gets too hot in heat mode or too cold
in cool mode. For heat pumps, this information is also used to control the
auxiliary heat to maintain a minimum supply air temperature of 88
degrees. See Capacity Controller section, page 11, for further information.
The Zone Dampers are air valves placed in the forced air duct work
for each zone. They are controlled by the System Controller. While the
HVAC system is running, the zone dampers for any zone thermostats not
calling will close and zone dampers for the zones calling will remain
open. Conditioned air is only directed to the zones needing it. See pages
14 to 18 for further information.
The Zone Thermostats monitor the room temperature of each zone
and compare it to the heat and cool setpoints stored in them. If the room
temperature drops below the heat setpoint, the zone thermostat makes
a heat call telling the System Controller that zone needs heating. If the
room temperature rises above the cool setpoint, that thermostat makes
a cool call telling the System Controller that zone needs cooling.
Two-stage thermostats are not required with the DigiTract 4-2 System.
The System Controller will cycle staging and auxiliary strip heat based on
leaving air temperature. See pages12 to 13 for further information.
The Bypass Damper is a pressure relief valve placed between the
supply and return ducts of the forced air duct work. As zone dampers
start closing, the bypass damper will open and divert some of the supply
air to the return. This prevents a pressure buildup in the supply duct
which can cause fan cavitation, excessive air velocities, and excessive
zone damper blow-by. See pages 18 to 22 for further information.
Damper Transformer. Wired to TR1 and TR2 on the System Controller.
Powers the zone dampers only. Requires an in-line fuse. See Damper
Transformer section, page 23.
System Controller
Leaving Air Sensor
Zone Damper
Zone Thermostat
Bypass Damper
Damper
Transformer
1
2
3
4
5
6

Digitract 4-2 COMPONENT SELECTION GUIDE
2
GAS/ELECTRIC HEAT PUMP
SYSTEM CONTROLLER
(DTGE4-2)
2-Stage Heat/Cool
COMMUNICATING
(DIGICOM)
ZONE DAMPERS
HEAT PUMP THERMOSTATS
(One per zone. Field Supplied.
See Thermostat Compatibility section, pg. 12)
Round (TR diam)
5 TONS AND UNDER
(Up to 0.5”S.P.)
Rectangular (TREC W x H)
OVER 5 TONS
(Up to 1”S.P.) (Up to 1.75”S.P.)
Round (101AMPD diam)
Rectangular (101CD W x H)
Rectangular
(101MRTD W x H)
BYPASS DAMPERS
5 TONS AND UNDER
BAROMETRIC BYPASS
Round (101ABBD diam)
Rectangular (RBB W x H)
PROGRAMMABLE
DIGITAL
(101PROG)
(SADIGI)
OVER 5 TONS
ELECTRONIC BYPASS
Round (STMPD diam)
Rectangular (STCD W x H)
STATIC PRESSURE CONTROLLER
(101ASPC)
BYPASS TRANSFORMER
(FIELD SUPPLIED. 24VAC, 40VA)
COMPLETE SYSTEM
GAS/ELECTRIC THERMOSTATS
START
DAMPER TRANSFORMER
(Field supplied. Requires in line fuse.
See Transformer/Fuse Sizing Table, pg. 23)
COMMAND CENTER
(101CEC Communication Package,
one per 20 thermostats)
CAPACITY CONTROLLER
System Controller includes Capacity Control
and Leaving Air Sensor
(DTHP4-2)
3-Stage Heat/2-Stage Cool
System Controller includes Capacity Control
and Leaving Air Sensor
CAPACITY CONTROLLER
COMMUNICATING
(DIGIHP)
SYSTEM CONTROLLER

3
Y1 G W1
PWR DPR1 DPR2 DPR3 DPR4
ON
-
R
C
Y1
+1
2
3
3
4
4
TR1
TR2
2
1
DIGITRACT 4-2 GE TWO STAGE 220108 AB
JPR1
Vx.x
R72
Y2
R8
R10
R9
R5
W2
G
W1
Y2
Y2
W1
G
W2
Y1
R
C
ZONE 1
THERMOSTAT ZONE 3 THERMOSTAT
-
+
STAT 1
W R Y G C
STAT 2
W R Y G C
STAT 3
W R Y G C
W R Y G C
STAT 4
W R Y G C
W R Y G C
W2
AIR FLOW
BYPASS
TAP
BYPASS
RETURN
WIRING – GAS/ELECTRIC DTGE4-2
HVAC unit and LAS terminals. Do not connect Y2 or W2 for single stage heat/cool systems.
Use minimum 18 gauge for all wiring.
All wiring must meet state and local codes.
Zone damper terminals. Refer to “Wiring –Zone Dampers”section, pg. 5.
1. LAS. Locate the leaving air sensor in the supply air stream, as far from the coil/heat exchanger as possible
before the bypass takeoff. Do not locate the LAS downstream of the bypass takeoff. Ensure wire polarity is
correct. Refer to "CAPACITY CONTROLLER- LAS INSTALLATION" on P. 11 for further information.
NOTE: Shielded conductor provided for installations with spark ignition or distances from controller to LAS
beyond 10’. 18/2 thermostat wire may be used in most applications.
2. Connect W2 and Y2 of the DTGE4-2 only if there are two heat and/or two cool stages.
3. Connect C from the controller to the thermostat 24V AC common terminal if hard wired. Not required
with use of battery operated thermostats. Refer to "THERMOSTATS- COMPATIBILITY" on P. 12 for further
information.
4. Zone damper terminals. Refer to "WIRING- ZONE DAMPERS" on P. 5.
5. Install one 24V AC transformer, sized and fused for the total number of zone dampers. See "DAMPER
TRANSFORMER" on P. 23.
6. Fan cycling jumper: A –FAU fan control; B –electric heat, fan on with heat call
1
1
2
3
4
5
6
2
3
4
5
6
DigiTract 4-2 Gas/Electric 2-Stage Heat/Cool

LAS. Locate the leaving air sensor between the refrigerant coil and the electric heat coil(s) or other auxiliary
heat source. Verify that the polarity is correct. Refer to “CAPACITY CONTROLLER –LAS INSTALLATION”
page 11, for further information.
Connect W2 from the controller to the unit’s electric heat stage terminal designation. It is recommended to
install an outdoor thermostat in series with any electric heat stages.
Connect C from the controller to the thermostat 24V AC common terminal if hardwired. Refer to “ZONE
THERMOSTATS –COMPATIBILITY”page 12, for further information.
Zone damper terminals. Refer to “WIRING –ZONE DAMPERS”on page 5.
Install one 24V AC transformer, sized and fused for the total number of zone dampers. See “DAMPER
TRANSFORMER”on page 23.
Emergency heat terminal, E. Use only if emergency heat source is different from auxiliary heat W2. If used,
do not jumper to W2.
Reversing valve jumper: B –energize for heat; O –energize for cool
NOTE: Some combination thermostats do not have an E terminal. Connect W2 of the thermostat to the E ter-
minal of STAT 1 terminal block.
4
Y1 G W2
PWR DPR1 DPR2 DPR3 DPR4
ON
-
R
E
L
C
O/B
+1
2
3
3
4
4
TR1
TR2
2
1
DIGITRACT 4-2 HP TWO STAGE 210806 BO
JPR1
Vx.x
R72
O/BRYGC
STAT 4
O/B RYGC
STAT 3
O/BRYGC
STAT 2
STAT 1
O/B RYGC
E
L
Y2
O/B
R8
R10
R9
R5
Y2
Y1
G
W2
W
G
Y1
Y2
O/B
R
E
C
+
-
AIR FLOW
O/B RYGCWL
ZONE 1
THERMOSTAT
O/B R Y G C
ZONE 3
THERMOSTAT
1
2
3
4
7
5
6
BYPASS
TAP
BYPASS
RETURN
WIRING – HEAT PUMP DTHP4-2
1
2
3
4
5
6
7
DigiTract 4-2 HP 3-Stage Heat/2-Stage Cool

5
WIRING – ZONE DAMPERS
FUSED 24VAC XFMR.
Transformer and fuse must be sized for total number of
zone dampers. See Transformer/Fuse Sizing Table on
page 23.
TR
SERIES
DAMPER
M M
1
2
3
3
4
4
TR1
TR2
2
1
DIGITRACT 4-2
SYSTEM
CONTROLLER TO TWO MORE TR SERIES
DAMPERS IF APPLICABLE
Method 1: Wiring Up to Three TR Series Dampers to a Zone
DMPR
1DMPR 2
M M M M
DMPR
3
M M
DMPR
4
M M
1
2
3
3
4
4
TR1
TR2
2
1
TO ADDITIONAL
TR SERIES
DAMPERS IF
APPLICABLE
FUSED 24VAC XFMR.
Transformer and fuse must be sized for total number
of zone dampers. See Transformer/Fuse Sizing
Table on page 23.
DIGITRACT 4-2
SYSTEM
CONTROLLER
24VAC
relay
Method 2: Wiring More than Three TR Series Dampers to a Zone
1
2
3
3
4
4
TR1
TR2
2
1
DIGITRACT 4-2
SYSTEM
CONTROLLER
N/C - No connection
*- Factory wired motor
101 series dampers include:
101AMPD, 101MRTD & 101CD
DAMPER RELAY BOARD
RC MCRCWWY RO
TB2
TB1
N/C N/CN/C
N/C N/C N/CN/CN/C ***
101 SERIES DAMPER
TO ADDITIONAL
101 SERIES DAMPERS
IF APPLICABLE
FUSED 24VAC XFMR.
Transformer and fuse must be sized for total
number of zone dampers. See Transformer/Fuse
Sizing Table on page 23.
GRd BWWY
B must wire to bottom
terminal and Rd must wire
to top terminal. Do not
reverse. {
{
G must wire to TR2.
Do not wire to TR1.
Method 3: Wiring 101 Series Medium/Heavy Duty Dampers to a Zone
There are three methods of wiring the zone dampers. If necessary, you
can mix wiring methods on different zones to suit your application.
Method 1: If wiring two or three TR series dampers to a zone, wire per
method 1.
Method 2: If wiring more than three TR series dampers to a zone, use
method 2. This method requires a 24V ac, SPNO relay.
Method 3: If using 101 series dampers with a DTGE4 controller, wire
per method 3. Notice: 101 series dampers are required for all systems
over 5 tons. Refer to Parts Selection Table, page 14.

6
The DigiTract 4-2 System Controller is the heart of the Digitract 4-2
zoning system. It is an auto changeover, home run system with a built in
staging and capacity controller. The function of the System Controller is
to receive calls from the zone thermostats, operate the HVAC system in
either heat or cool mode, and close the zone damper(s) of the zones not
calling for the operating mode. The mode of operation is determined by
the first call received. If thermostats are calling for opposite modes,
every 15 minutes it will change over to the other mode as long as there
are opposing calls. The built in Capacity Controller maintains the supply
air temperature within an operating range to prevent freeze ups and
overheating. For heat pumps, the DTHP4 System Controller will also
control the auxiliary heat to maintain an 88 degrees minimum coil
leaving air temperature.
The DigiTract 4-2 is available in two models, Gas/Electric 2-Stage
Heat/Cool and Heat Pump 3-Stage Heat/2-Stage Cool.
SYSTEM CONTROLLERS
SYSTEM CONTROLLER – GAS/ELECTRIC DTGE4-2
OPERATION
Y1 Y2 G W1 W2 PWR DPR MODE FUNCTION
OFF OFF OFF OFF OFF OFF OFF Off Power off.
OFF OFF OFF OFF OFF ON OFF On Power on, blower off, all zones satisfied.
OFF OFF ON ON OFF ON 0 Vent Blower on, compressor(s) off, all zone dampers open.
OFF OFF ON OFF OFF ON 1 Purge Blower on, compressor(s) off. Dampers with LED on are closed.
ON OFF ON OFF OFF ON 1 Y1 cool 1st stage cool, blower on. Dampers with LED on are closed.
ON ON ON OFF OFF ON 1 Y2 cool 2nd stage cool, blower on. Dampers with LED on are closed.
OFF OFF A / B ON OFF ON 1 W1 heat 1st stage heat, blower on. Dampers with LED on are closed.
OFF ON A/ B ON ON ON 1 W2 heat 2nd stage heat, blower on. Dampers with LED on are closed.
OFF OFF ON OFF OFF FL 1 Cap cut out Blower on, all compressors off. Dampers with LED on are closed.
STATUS LEDS
FL = Flashing A= On when JMPR1 is in A position B= OFF when JMPR1 is in B position
1= One or more damper LED’s on 0= All damper LED’s are off
The System Controller will initially run in the mode requested by the first
calling zone thermostat.
Cool mode –When running in the cool mode, the System Controller
energizes the compressor(s) and indoor blower. This is indicated by the
corresponding Y and G LEDs illuminating. Dampers for the zones not
calling for cool are powered closed and the dampers for the zones
calling for cool are left open. This is indicated by the DPR LEDs. If the
DPR LED is illuminated on the damper terminal strip and damper
terminal board, the corresponding damper is closed. The system will
continue to run in the cool mode until all calls are satisfied or
changeover occurs. When all calls are satisfied or prior to changeover,
the system will go into a purge mode.
Heat mode –When running in the heat mode, the System Controller
energizes the heat stage(s), indicated by the W LEDs illuminating. If the
Fan Control Jumper is in the B position, the indoor blower will energize
with heat, indicated by the G LED illuminating. Dampers for the zones not
calling for heat are powered closed and the dampers for the zones calling
for heat are left open. This is indicated by the DPR LEDs. If the DPR LED
is on the damper terminal strip and damper terminal board, the corre-
sponding damper is closed. The system will continue to run in the heat
mode until all calls are satisfied or changeover occurs. When all calls are
satisfied or prior to changeover, the system will go into a purge mode.
Changeover –While the system is operating in one mode, and the
System Controller receives a call for the opposite mode, the System
Controller will continue to run in the current mode for 15 minutes or
until all current calls are satisfied. Then the System Controller will go
into a purge mode for 3 minutes, then change over to the new mode.
Purge mode –When all calls are satisfied or before changing
modes, the System Controller will go into a three minute purge cycle.
During this mode, the compressor or heat will turn off and the indoor
blower fan will continue to run. This is indicated by the W and Y LEDs
off and the G LED on. The damper(s) of the last calling zones will
remain open and all other damper(s) will be closed. This allows the
supply air to adjust to room temperature before changeover or ventila-
tion while providing a time delay to prevent short cycling. The DPR
LEDs indicate which dampers are open and which are closed. If the
DPR LED is on, the damper is closed. If the DPR LED is off, the damper
is open.
Ventilation –When no zones are calling, all zone dampers are open.
During this time, if any thermostat has the fan switch ON then the indoor
blower is energized (G made to R) and the G LED is on. This provides
ventilation to all zones.

A. HVAC Unit/LAS Terminals –Connects to HVAC unit and
Leaving Air Sensor (LAS).
±: LAS terminals. The LAS monitors the leaving air
temperature.
W1: First stage heat. When energized (W1 made to R),
energizes first-stage heat.
W2: Second stage heat. When energized (W2 made to R),
energizes second-stage heat.
G: Blower. When energized (G made to R),
energizes the indoor blower.
Y1: First stage cool. When energized (Y1 made to R),
energizes first stage cooling.
Y2: Second stage cool. When energized (Y2 made to R),
energizes second stage cooling.
R: HVAC unit 24V power. Powers the DigiTract 4-2 board
and zone thermostats.
C: HVAC unit 24V power return.
B. Thermostat Terminals –Connects up to four zone
thermostats.
W: Heat call. When energized (W made to R),
requests the Digitract 4-2 to run in heat mode.
R: HVAC unit 24V power.
Y: Cool call. When energized (Y made to R),
requests the Digitract 4-2 to run in cool mode.
G: Blower Fan- When energized (G made to R), requests the
DigiTract 4 to turn on the indoor blower fan.
C: HVAC unit 24V power return.
C. Damper Terminals –Connects dampers for up to four zones and
damper power supply.
TR1/
TR2: 24V AC transformer terminals. This transformer powers only
the zone dampers.
1 1: Zone damper 1.
When energized, powers zone damper 1 closed.
2 2: Zone damper 2.
When energized, powers zone damper 2 closed.
3 3: Zone damper 3.
When energized, powers zone damper 3 closed.
4 4: Zone damper 4.
When energized, powers zone damper 4 closed.
D. Damper Status LEDs –On when corresponding zone damper is
being powered closed.
E. Board Number –This number indicates the circuit board number
and revision. May need to know this number if conferring with
technical support.
F. Heat Mode Fan Control Selection Jumper –In the A position,
the blower is energized by the furnace when heat is energized
(gas furnaces). In the B position, the blower is energized by the
DTGE4-2 when heat is energized (electric furnaces).
G. Microcontroller –Responsible for activation and control of the
unit based upon thermostat input. Occasionally software upgrades
may become available. If so, the Digitract 4-2 software can be field
upgraded by changing this microcontroller.
H. HVAC System Status LEDs –Indicates what the DTGE4-2 is
energizing on the HVAC system.
Y1: Compressor, yellow. On when the first-stage cool is energized.
Y2: Compressor, yellow. On when the second-stage cool is energized.
G: Blower, green. On when the indoor blower is energized.
W1: Heat, red. On when first stage heat is energized.
W2: Heat, red. On when second stage heat is energized.
PWR: Power, orange. On when power at R and C and the Power
Switch is on. Flashing when in Capacity Control cut out mode.
See Status Lights section, page 6, for further information.
I. Leaving Air Sensor Potentiometer –Turn to calibrate the
leaving air sensor if required. See Calibration in Capacity Controller
section.
J. Power Switch –When OFF, power from the HVAC unit transformer is
disconnected from the Digitract 4-2 and thermostats. When ON, power
from the HVAC unit transformer is supplied to the Digitract 4-2 and
the zone thermostats.
7
SYSTEM CONTROLLER – GAS/ELECTRIC DTGE4-2
Y1 G W1
PWR DPR1 DPR2 DPR3 DPR4
ON
-
R
C
Y1
+1
2
3
3
4
4
TR1
TR2
2
1
DIGITRACT 4-2 GE TWO STAGE 220108 AB
JPR1
Vx.x
R72
Y2
R8
R10
R9
R5
W2
G
W1
Y2
ZONE 1
THERMOSTAT ZONE 3 THERMOSTAT
STAT 1
W R Y G C
STAT 2
W R Y G C
STAT 3
W R Y G C
STAT 4
W R Y G C
W R Y G CW R Y G C
W2
A
B
C
D
E F
G
H
I
J
COMPONENTS

8
The System Controller will initially run in the mode requested by the first
calling zone thermostat.
Cool mode –When running in the cool mode, the System Controller
energizes the compressor(s), indoor blower and energizes the
reversing valve (O/B made to R) if the reversing valve selection jumper
is in the O position. This is indicated by the corresponding Y, G and O/B
(if jumper in O position) LEDs illuminating. Also, the dampers for the
zones not calling for cool are closed and the dampers for the zones
calling for cool are left open. This is indicated by the DPR LEDs. If the
DPR LED is illuminated, the damper terminal strip and damper
terminal board, the corresponding damper is closed. The system will
continue to run in the cool mode until all calls are satisfied or
changeover occurs. When all calls are satisfied or prior to
changeover, the system will go into a purge mode.
Heat mode –When running in the heat mode, the System Controller
energizes the compressor(s), indoor blower and energizes the
reversing valve if the reversing valve selection jumper is in the B
position. This is indicated by the corresponding Y, G and O/B (if
jumper in B position) LEDs illuminating. Also, the dampers for the
zones not calling for heat are closed and the dampers for the zones
calling for heat are left open. This is indicated by the DPR LEDs. If the
DPR LED is on the damper terminal strip and damper terminal board,
the corresponding damper is closed. After running in heat mode for 8
minutes, the System Controller will energize the auxiliary heat if the coil
leaving air temperature drops below 88 degrees and will deenergize
when the coil leaving air temperature rises above 97 degrees. The W2
LED is on when the auxiliary heat is energized. The system will continue
to run in the heat mode until all calls are satisfied or changeover
occurs. When all calls are satisfied or prior to changeover, the system
will go into a purge mode.
Changeover –While the system is operating in one mode, if the
System Controller receives a call for the opposite mode, the System
Controller will continue to run in the current mode for 15 minutes or
until all current calls are satisfied. Then the System Controller will go
into a purge mode for 3 minutes, then change over to the new mode.
Purge mode –When all calls are satisfied or before changing modes,
the System Controller will go into a 3-minute purge cycle. During this
mode the compressor and indoor blower will deenergize. This is
indicated by the Y and G LEDs cycling off. If the reversing valve is
energized, it will deenergize. This is indicated by the O/B LED turning
off. The damper of the last calling zone will remain open and all other
dampers will be closed. This provides a 3-minute time delay to prevent
equipment short cycling. The DPR LEDs indicate which dampers are
open and which are closed. If the DPR LED is on, the damper is closed.
If the DPR LED is off, the damper is open.
Auxiliary heat –8 minutes after the System Controller has run in heat
mode, if the coil leaving air temperature is below 88 degrees, the
auxiliary heat is energized and the W2 LED illuminates. When the coil
leaving air temperature rises above 97 degrees, the auxiliary heat is
deenergized and the W2 LED cycles off.
Ventilation –When no zones are calling, all zone dampers are open.
During this time, if any thermostat has the fan switch ON then the
indoor blower is energized and the G LED is on. This provides
ventilation to all zones.
Emergency heat –Emergency heat mode is controlled by STAT1 only.
To make an emergency heat call, STAT1 must be in Emergency Heat
mode and making a heat call. When the System Controller receives an
emergency heat call from STAT 1, it will lock-out the compressors and
energize the auxiliary heat strips and fan unless the system is already
running in heat or cool mode. If the system is running, the unit’s
auxiliary heat will be energized based on leaving air temperature. Zones
not calling for heat will close their dampers. When all zone temperatures
are satisfied, the System Controller removes the auxiliary heat call and
monitors all zones for the next call.
SYSTEM CONTROLLER – HEAT PUMP DTHP4-2
OPERATION