RCS ZC2S User manual

RCS
MODELZC2S
2ZONEHVACCONTROLUNIT
INSTALLATION ANDOPERATIONMANUAL
DCN 141-00240-02
7/25/03

DCN: 141-00240-02 7/03 2
Introduction
The ZC2S two zone HVAC Control Unit allows 2 standard electronic thermostats to connect to a single heating
and cooling HVAC mechanical system. It provides two independent “zones” of temperature control by controlling
the mechanical system and motorized dampers in each zone.
The ZC2S is for use with any residential style standard gas or electric heating HVAC system up to 5 ton
capacity. The control unit supports one stage heating and one stage cooling systems.
The two zones are truly independent and can be in either heating or cooling modes. The control unit features
auto changeover from heating to cooling modes and gives heating calls priority.
The ZC2S operation is fully automatic and transparent to the user. Each zone thermostat provides the complete
and independent control for that zone. You can think of each zone as having a separate heating/cooling system
with its own thermostat.
Each zone Thermostat determines the operation of the heating and cooling system so you should refer to your
Thermostat Manual for information on how to “operate” the system.
Thermostats for use with the ZC2S
The ZC2S works with most ELECTRONIC thermostats (Honeywell, White Rogers, Lux). Use only thermostats
that are either battery operated or that use both sides of the 24VAC power (they have R and C terminals)
from the HVAC system
DO NOT USE POWER STEALING THERMOSTATS!
Typically these thermostats “steal” power from the “W” or Heat connection on the HVAC system. THESE WILL
NOT WORK WITH THE ZC2S ZONE CONTROL UNIT.
It is also recommended that you do not use older style mechanical thermostats that use “anticipator” circuits as
these will not function properly.
Thermostats connect to the zone control unit terminals the same as they would connect to the HVAC system.
Zone Dampers for use with the ZC2S
The ZC2S provides independent control of temperature by regulating the flow of conditioned air to the zones by
motorized dampers. The system uses two position, on/off control.
The controllers are designed to work with normally open, two position, spring return, 24VAC, 2 wire motorized
dampers, such as the RCS RD Series of round motorized dampers. These dampers draw .5A each.
Normally open dampers are used to provide fail-safe operation, assuring condition air will be available even if a
damper motor fails. When zone 1 calls for heating or cooling, the zone 2 damper closes.
Maximum rated current for all dampers is 1 Amp. ( typically 2 dampers).
HVAC Systems Compatibility
The ZC2S is designed to work with most standard gas/electric residential style heating and cooling systems and
provide the following outputs to the HVAC system.
One stage of heating: W output

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One stage of cooling: Y output
Fan: G output
The Fan output is selectable for normal gas heating system operation with no fan output with heat calls or for
electric heating systems which require fan output with heat calls.
The controllers connect to the HVAC systems at their standard thermostat connections and function just like a
thermostat to the system. Consult your HVAC thermostat wiring diagram for verification of compatibility with the
zone control units.
Thermal Equalizer Feature
The ZC2S version of the controllers includes the exclusive patented THERMAL EQUALIZER feature. This is
used in two story, forced air applications to reduce the effects of heat stratification. Heat rises naturally and
during heating cycles the upstairs zone tends to overheat. This loss of heat to the upstairs keeps the downstairs
zone cooler and calling for more heat. This process continues until the upstairs is uncomfortably hot and the
downstairs is still calling for more heat.
To balance this natural phenomena, the THERMAL EQUALIZER feature will monitor the length of time the heat
has been calling downstairs and after a selectable time period, will stop the heat call and recycle the overheated
upstairs air back down to the downstairs zone. This “equalizer cycle” will reduce the heat buildup upstairs and
put the heat back downstairs where it is still needed. The net effect is a more comfortable temperature in the
upstairs zone and an energy saving reuse of the excess heat in the downstairs zone.
The Thermal Equalizer feature monitors Zone 1 for heat run times and this zone must be the “downstairs zone”.
When the Thermal Equalizer cycle is on, the Zone 2 damper will be closed and the high speed fan turned on.
Zone 2 must be the “upstairs zone” when using the Thermal Equalizer feature.
Short Cycle Protection Delay
The ZC2S control unit provide a 5 minute delay between successive compressor operations for short cycle
protection. This delays one zone from calling for compressor operation shortly after another has stopped and
prevents potential damage to the compressor due to rapid off-on cycling. Most thermostats also have built-in
short cycle protection delays, so remember these compressor cycle delays are normal when trouble shooting the
system. For testing purposes, you can reset the controller’s 5 min delay by removing power from the controller.
Status Led
The status LED will flash one time every second for normal operation. During certain other modes of operation
the LED will flash differently to indication these modes. See table below.
LED Flash Modes
One Flash Normal Operation
Two Flashes Equalizer Cycle On
Three Flashes Short Cycle Protection Delay On. (Compressor output inhibited)

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Installation
Install the controller near the HVAC mechanical system or in a convenient indoor service location, such as the
garage, basement, closet or utility room.
Mount the controller to the wall or structural bracing. Mounting the controller onto the HVAC unit is possible but
generally not desirable due to the potential for excessive vibration and heat.
Wiring
Thermostats. Use standard 18GA thermostat wiring to connect the thermostats to the controller and the
controller to the mechanical system.
Dampers. Zone damper outputs provide 24VAC at 1 Amp maximum to the dampers. Use 18 gauge thermostat
wire for the dampers.
Power
ZC2S Control Units are powered from the HVAC system’s 24VAC R and C (common) terminals. No external
transformer is required. Total damper draw must be limited to 1 Amp per zone.
Fuse
The controller is supplied with a 2AG style 2 Amp fuse.
Thermostat Wiring
Connect the zone thermostats to their respective zone input terminals, J1 & J2. Both the 24VAC Common (C)
and 24VAC (R) power is available at these terminals. Only the 24VAC (R) terminal is required for proper input
from the thermostats. The 24VAC Common (C) is provided for thermostats that require power from the system.
ZONE 1 THERMOSTAT
24VAC COM C
24VAC R
FAN G
HEAT W
COMP Y
ZC2S CONTROL UNIT
ZONE 1 INPUT
24V C
24V R
FAN G
HEAT W
COMP Y
OPTIONAL FOR POWER IF REQUIRED
FIG 1. WIRING THERMOSTATS TO THE CONTROLLER

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HVAC System Wiring
The ZC2S control units connect to the HVAC mechanical systems at the normal thermostat connections on the
HVAC indoor units.
WIRING FOR STANDARD HVAC SYSTEMS
Control Unit Setup: Dipswitch Settings
The control unit has a configuration dipswitch, SW1. Set the dipswitch as follows.
SW1 Position 1: Test Mode (For service technician use only, do not run in test mode)
Select OFF for Normal operation. All delays normal.
Select ON for Test mode to reduce delays to 10 seconds and shorten run times to one minute to facilitate
system checkout and troubleshooting.
SW1 Position 2: Fan Mode Select
Select OFF for Standard Gas systems (no fan with heat calls)
Select ON for Electric Heating systems (fan with heat calls)
SW1 Position 3& 4: Thermal Equalizer Mode Select
These two dipswitch positions determine the length of time the equalizer cycle will run after it has been tripped on
by the Heat Run Time timeout.
C 24VAC COM
R 24VAC
G FAN
W HEAT
Y COMP
R 24VAC
G FAN
W HEAT
Y COMPRESSOR
RED
GREEN
WHITE
YELLOW
INDOOR
FURNACE UNIT OUTDOOR UNIT “COMPRESSOR”
Y COMP
C 24VAC COM
ZONE CONTROL
UNIT
HVAC SYSTEM
Standard Thermostat
Wiring Color Codes
FIG 2. WIRING ZONE CONTROL UNIT TO STANDARD HVAC SYSTEM
OFF ON
3 Off: Equalizer feature Off.
4 Off
3 On Equalizer run time 6 Min
4 Off
3 Off Equalizer run time 8 Min
4 On
3 On Equalizer run time 10 Min
4 On
SW1
FIG 4. DIPSWITCH SW1
EQUALIZER RUN TIME
SETTINGS
ERT1
ERT2

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SW1 Positions 5& 6: Thermal Equalizer Heat Run Time Mode Select
These two dipswitch positions determine the length of time that a Zone 1 Heat Call can be on before it times out
and is interrupted by an equalizer cycle.
OFF ON
5 Off Heat Run Time 8 Min
6 Off
5 On Heat Run Time 12 Min
6 Off
5 Off Heat Run Time 16 Min
6 On
5 On Heat Run Time 20 Min
6 On
SW1
FIG 5. DIPSWITCH SW1
EQUALIZER HEAT RUN TIME
SETTINGS
HRT1
HRT2

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SW1-1 TEST MODE
OFF = NORMAL OPERATION
ON = TEST MODE
-
ALL DELAYS CANCELED
1
1
S
W1
-
2 FAN MODE SELECT
OFF = Gas Systems. NO fan w/heat
ON = Electric Systems. Fan w/heat
2
2
DAMPERS
FUSE
2 ZONE HVAC CONTROLLER
MODEL: ZC2S
PN: 001-00240
ZC2S REV E
NORMAL1
STD FAN 2
EQ OFF 3
4
5
6
TEST MODE
F/HEAT
ERT1
ERT2
HRT1
HRT2
SW1
OFF -ON
2AG
2A
STATUS LED
1 FLASH = OK
2 FLASH = EQ ON
3 FLASH = SCP ON
ZONE1
ZONE2
FAN
HEAT
COMP
•For Standard Thermostats
•For Standard HVAC Systems
•One Stage Heat, One Stage Cool
•Thermal Equalizer Feature
WIRING DIAGRAM
Standard
Thermostats
Motorized Dampers
Normally Open
24VAC
Two Position
Spring Return
SW1 DIP SWITCH SETTINGS
REV E
RCS
OPTIONAL
POWER TO
STATS
24V C
24V R
FAN G
HEAT W
COMP Y
24V C
24V R
FAN G
HEAT W
COMP Y
ZONE 1
ZONE2
24V C
24V R
FAN G
HEAT W
COMP Y
75
24V C
24V R
FAN G
HEAT W
COMP Y
75
24V COM
R 24V
G FAN
W HEAT
Y COMP
HVAC SYSTEM
C 24V COM
R 24V
G FAN
W HEAT
Y COMP
Standard
HVAC System
Outdoor
Compressor
C
Y
RESET
STATUS LED: The status LED shows normal operation by flashing slowly. If the Status LED is not flashing, check power/fuse.
Two flashes indicate that the Equalizer run cycle is on. Three flashes indicate that the Short cycle protection is on.
SHORT CYCLE PROTECTION (SCP) DELAY. The control unit protects the compressor from short cycling by a 5 minute delay at
the end of
every compressor “run” cycle. The Status LED will flash rapidly three times to indicate SCP delay is active.
Zone 1
Com
Zone 2
Com
SW1-3 & 4 EQUALIZER MODE SELECTION
Equalizer OFF
Equalizer Run Time = 6 Min
Equalizer Run Time = 8 Min
Equalizer Run Time = 10 Min
3
4
3
4
3
4
3
4
SW1-5 & 6 HEAT RUN TIME SELECTION
Heat Run Time = 8 Min
Heat Run Time = 12 Min
Heat Run Time = 16 Min
Heat Run Time = 20 Min
5
6
5
6
5
6
5
6
Note: There is a 2 Min Minimum
Heat Run Time (MHRT). If the
Heat Call is terminated during this
period, no Equalizer cycle will be
started at the end of the call. If
the Heat Call last longer than the
MHRT, but less than 8 Min, then
an Equalizer cycle will be started
at the end of the call.
Dipswitch Settings: