HAI Omnistat RC-120 User manual

O M N I S T A T
ELECTRONIC COMMUNICATING THERMOSTAT
Installation Manual
RC-120 Two Stage Heat/Cool
2 Stage Heat / 2 Stage Cool
Document Number 13I00-7
January, 1997

Copyright © 1997 Home Automation, Inc.
All Rights Reserved

CONTENTS
DESCRIPTION ....................................1
INSTALLATION ...................................1
LOCATION ......................................2
REMOVING AN EXISTING THERMOSTAT ..................2
MOUNTING ......................................3
TYPICAL WIRING DIAGRAMS ........................6
POWER UP .......................................8
DISABLE KEYS ...................................9
INSTALLER SETUP ................................9
OWNER'S MANUAL ................................14
QUICK REFERENCE SETUP GUIDE ....................15
REMOTE SYSTEM WIRING DIAGRAMS ................16
TROUBLESHOOTING TIPS ..........................18

DESCRIPTION
The RC-120 is a precision digital thermostat designed for 24 VAC
two stage heating and cooling systems. It has the capability of being
controlled both locally and by remote control. It offers
programmability, stand alone operation, and robust, optically isolated
communications with automation systems, utility control systems,
and personal computers.
Electrical rating: 24 V; 3 A; 50/60 Hz
Maximum current: 2 A on any circuit, 3 A total
Thermostat operating current: less than 15 mA
The following requirements must be observed for installation in
Europe: CE
1.This equipment must be installed in accordance with National
wiring rules for the country in which it is installed.
2.Fuses must be replaced only with IEC rated components.
3.All product labels, instructions and markings relating to safety
must be translated to a language which is acceptable in the
country in which this equipment is to be installed.
INSTALLATION
Before installing this thermostat:
1.Read all of the installation instructions carefully.
2.Read the Owner's Manual carefully.
3.Ensure that this product is suitable for your application.
4.Ensure that wiring complies with all codes and ordinances.
5.Disconnect power to the control transformer to prevent electrical
shock and damage to equipment.
6.Select an appropriate location to ensure an accurate temperature
reading.
1

LOCATION
When replacing an existing thermostat, install the RC-120 in the
same location. If the existing location doesn't meet the following
criteria, choose a new location to mount the RC-120.
When choosing a location for the thermostat:
1.Ensure that the thermostat is mounted about 5 feet above the
floor and is at least 2 feet from an outdoor wall.
2.Ensure that the thermostat is located in an area where there is
adequate air circulation.
3.Do not mount in the path of direct sunlight or of radiant heat
generated by appliances.
4.Do not mount behind an outdoor wall, near a fireplace, or in the
path of any air ducts.
REMOVING AN EXISTING THERMOSTAT
1.Disconnect the power to the control transformer.
2.Remove the cover to the existing thermostat.
3.Disconnect the wires going to each terminal on the thermostat.
Label each wire with the letter or number at the terminal.
4.Remove the existing plate or base from the wall.
2

MOUNTING
When mounting the RC-120, grasp the thermostat by the sides,
avoiding the keys, and unsnap the base from the face.
Holding the base to the wall so that the word "TOP" is upright and
facing you:
1.Mark the two mounting holes on the wall using a pencil.
2.Drill a hole using a 3/16" bit at each mounting hole marking.
3.Install the two wall anchors supplied.
4.Slide the system wires through the opening in the base.
5.Mount the base to the wall using the two #6 x 1/2" self-tapping
screws supplied - See Figure 1.
Figure 1 - Mounting thermostat base
3

Connect each wire to the terminal strip on the thermostat base per the
wiring diagram for your system application - See Figures 4 - 5.
Form the thermostat wiring so that the cable lies flat between the
terminal strip and the center of the thermostat base - See Figure 2.
Figure 2 - Forming thermostat wiring
If a remote system is being used with the thermostat, connect the
remote system wiring to the supplied cable using the wire splices per
the diagram for your remote system application - See Figures 7 - 8.
Insert the cable into the connector on the thermostat circuit board
marked "COMM".
Upon completion of wiring the thermostat, push all excess wiring
into the hole in the wall. Plug the hole with the supplied insulating
foam to ensure an accurate temperature reading by the thermostat.
4

Align the tabs of the thermostat face with the slots of the thermostat
base. Gently push the thermostat face into the thermostat base
locking it into place - See Figure 3.
Figure 3 - Mounting thermostat face to thermostat base
Note:
Be sure that the thermostat temperature sensor is standing up, and
that it has not been damaged during installation.
SLOT TAB
WALL BASE
FACE
TEMPERATURE
SENSOR
5

TYPICAL WIRING DIAGRAMS
CAUTION
1. Be sure to disconnect the power to the control
transformer before removing or installing thermostat.
2. Do not short cooling or heating relays, or fan relay...
even momentarily. This will blow a non-replaceable
fuse.
3. Do not attempt to hook up to live circuits. An accidental
connection to a component on the thermostat circuit
board could cause damage to the thermostat.
Figure 4 - Thermostat power-up for test or demonstration purposes
6

FIGURE 5
7
2ND STAGE
COOLING
RELAY
FAN
R
Y2
C G
HEATING
1ST STAGE
TRANSFORMER
24VAC
1
2 3
4
5
6
7 8
W1
Y1
COOLING
1ST STAGE
24VAC "HOT" 24VAC "COMMON"
TWO STAGE HVAC SYSTEMRC-120
W1
Y1
C
Y2
G R
24VAC "HOT" FAN
24VAC "COMMON" 1ST STAGE
NOT USED COOLING COOLING
2ND STAGE
HEATING
1ST STAGE
W2
2ND STAGE
HEATING
W2
HEATING
2ND STAGE

POWER UP
1.Double check wiring, be sure that there are no stray wires or
wire strands at the connections.
2.It is not necessary to connect the remote system (COMM) cable
at this time.
3.Connect power to the control transformer and system. The
display will show all segments for about 5 seconds.
4.Press the Fan key. The fan should come on. Press the Fan key
again. The fan should go off.
5.Set the Mode to "HEAT". Use the up arrow key to raise the
desired temperature setting 1 degree above the current
temperature. Ensure that Stage 1 heat comes on. After a few
minutes, raise the desired temperature 3 degrees over the current
temperature. Stage 2 heat should come on. Set the mode to
"OFF". Ensure that the heat unit goes off.
5.Set the Mode to "COOL". Use the up arrow key to raise the
desired temperature setting 1 degree above the current
temperature. Ensure that Stage 1 cool comes on. After a few
minutes, raise the desired temperature 3 degrees over the current
temperature. Stage 2 cool should come on. Set the mode to
"OFF". Ensure that the cooling unit goes off.
Note: As a convenience to the installer, the compressor start up
protection delay can be canceled. To cancel the delay, press theProg
key 3 times, then press the Fan key 2 times.
If the thermostat or system do not perform as stated above, recheck
all wiring - See Troubleshooting Tips.
8

DISABLE KEYS
The keys on the thermostat can be disabled to prevent anyone from
controlling the thermostat locally. To disable the keys, solder a wire
jumper across the two holes on the circuit board as shown in Figure
6.
FIGURE 6
INSTALLER SETUP
This section describes the items that the installer must setup as part
of the thermostat installation. The Installer Setup mode is used to
configure the general operating parameters of the thermostat.
When in Installer Setup mode:
1.The small digits on the top of the display are the item number.
2.The large blinking digits in the center of the display are the value
of the item number.
3.Press the Prog (>) key to advance to the next item.
4.Press the Hold (<) key to return to the previous item.
5.Use the arrow keys (∧-∨) to change the value of each item.
6.Do not set the values to anything other than the specified range
for each item.
7.To exit Setup mode, press the Fan key.
SOLDER WIRE
JUMPER HERE
9

The thermostat will automatically exit Setup mode after 20 seconds
of no key activity.
To enter the Installer Setup, set Mode to "OFF". After 10 seconds,
press the Prog key three times (day will flash), then press the Fan
key.
The word "default" indicates the initial setting when the thermostat is
delivered from the factory.
00 Address
If you are using Communications Mode 0 or 1, and you are installing
more than one thermostat, each must be set to a consecutive address,
starting at 1. The default address setting is 1.
An address from 1- 127 may be selected.
01 Communications mode
The thermostat can communicate with remote systems in 4 different
modes. These modes are:
0 300 baud, RS-232 mode (for use with personal computers)
1 100 baud, System mode (Omni, OmniPro, and Aegis systems)
8 PESM mode, (use with Model 1503 automation systems)
24 Day/Night mode (for use with remote setback switch)
The default setting is 1.
ITEM NUMBER
VALUE
10

02 System options
The thermostat can be configured with the following system options:
0 Auto changeover no fan with heat
1 Auto changeover fan on with heat
4 Manual changeover no fan with heat
5 Manual changeover fan on with heat
12 Heat only no fan with heat
13 Heat only fan on with heat
20 Cool only
The default setting is 0.
03 Display options
The thermostat can be configured to display the following attributes:
0 Celsius am/pm time format programmable
1 Fahrenheit am/pm time format programmable
2 Celsius 24 hour time format programmable
3 Fahrenheit 24 hour time format programmable
4 Celsius am/pm time format non-programmable
5 Fahrenheit am/pm time format non-programmable
6 Celsius 24 hour time format non-programmable
7 Fahrenheit 24 hour time format non-programmable
The default setting is 1.
11

Add 16 to each setting to disable the clock and filter reminder
displays. This may be appropriate for non-programmable and
commercial use where the time display is not desired.
04 Calibration offset
This item is used to raise or lower the current temperature reading by
1 degree Fahrenheit or 1/2 degree Celsius. If this item is set to 30,
no change will be made. Each digit below 30 will lower to
temperature, and each digit above 30 will raise the temperature.
(1 = - 29 to 59 = + 29 - Temperature units - 30 = No change)
The default setting is 30.
05 Cool setpoint limit
This item is used to limit the temperature setting in cool mode. The
desired cool setting can never be set below this setting.
The default setting is 51.
06 Heat setpoint limit
This item is used to limit the temperature setting in heat mode. The
desired heat setting can never be set above this setting.
The default setting is 91.
07 Not used
08 Not used
09 Not used
10 Not used
11 Cooling minimum on/off time (minutes)
This item is used to limit the on and off times of the cooling system.
When the cooling system starts, it must remain on for the minimum
time set by this item. When the cooling system turns off, it must
remain off for a minimum time set by this item.
12

Setting Cycles per hour (maximum)
56
65
74
8 3.7
10 3
The recommended setting is 8 minutes. A higher setting may be
appropriate for buildings with low heat loss/gain.
The default setting is 8.
12 Heating minimum on/off time (minutes)
Same as Cooling minimum on/off time, for the heating system.
The default setting is 8.
13 Stage 2 Differential
This item specifies the temperature difference between stage 1 and
stage 2. The default setting of 2 (degrees F) is recommended for all
applications. In special cases a setting of 3 or 4 may be used when
precise control of temperature is not as important as highest energy
efficiency, however, the thermostat will not be able to maintain
temperature within 1 degree of its setting under severe weather
conditions. A setting of 1 or 0 is not recommended.
In this thermostat, the automatic anticipator will compensate for the
temperature "droop" caused by the stage 2 differential under cold
weather conditions.
The default setting is 2.
14 Clock adjust
If the clock on the thermostat is running faster or slower than the
actual time, you can have the thermostat automatically compensate up
to 29 seconds per day. The thermostat will add or subtract the
selected amount of time daily.
13

(1 = - 29 to 59 = + 29 - Seconds per day - 30 = No change)
The default setting is 30.
Note: If an HAI automation system is being used, the controller
system time is sent to the thermostat every minute. This adjustment
will have no effect.
15 Filter reminder
The thermostat logs the amount of time the system fan has been
running. When this setting reaches 0, the thermostat will display a
reminder to replace the filter. The setting is the amount of days (24
hours of system operation) before this reminder is displayed.
Days - Counting down from 10 - 0
16 System runtime (This week)
This item logs the amount of time (hours) that the heating and
cooling system was in operation this week.
17 System runtime (Last week)
This item logs the amount of time (hours) that the heating and
cooling system was in operation last week.
ANTICIPATION
Anticipation is performed electronically and is independent of the
type and load of the components in the heating and cooling
equipment. This thermostat has electronic control based on
proportional, integral and derivative components and maintains
temperature to within 1 degree F of the setting. Anticipation is not
adjustable.
OWNER'S MANUAL
Following Installer Setup, check the option boxes ( ) in the Owner's
Manual according to the configuration of the thermostat.
14

QUICK-REFERENCE SETUP GUIDE
This table displays each Installer Setup item with it's default setting.
The column labeled "CURRENT" can be used to write down the
current settings if any changes are made to the default settings.
Item Number Description Default Current
00 Address 1
01 Communication mode 1
02 System options 0
03 Display options 1
04 Calibration offset 30
05 Cool setpoint limit 51
06 Heat setpoint limit 91
07 Not used -
08 Not used -
09 Cooling anticipator -
10 Heating anticipator -
11 Cooling minimum on/off time 8
12 Heating minimum on/off time 8
13 Stage 2 differential 2
14 Clock adjust 30
15 Filter reminder 10
16 System runtime (This week) -
17 System runtime (Last week) -
15

REMOTE SYSTEM WIRING DIAGRAMS
This thermostat has been preprogrammed with energy saving settings
recommended under the EPA Energy Star program. When used with
remote systems, HAI recommends that the thermostat be configured
as "non-programmable" (See Setup Item 03 - "Display Options").
HAI AUTOMATION SYSTEMS
The thermostat can be connected to an HAI automation system. The
controller can send commands to the thermostat to change mode, cool
setting, heat setting, status of fan and hold, and other items.
Run a 3 (or 4) conductor wire from the HAI system to the thermostat
location. All thermostats on an Omni, OmniPro, and Aegis controller
are connected to Zone 16 and Output 8. Connect the red COMM
cable wire with the black COMM cable wire. Make the connections
(as shown in Figure 7) using the supplied wire splices.
Note: Do not connect the red COMM cable wire to 12V. If a 4
conductor wire is used, disconnect the red conductor. It is not used!
Figure 7 - Hookup to an HAI system
GRN RED BRN GRY
COMM
BLACK
RED
BLACK GREEN
YELLOW
OMNI
CONTROLLER
3 OR 4 CONDUCTOR
WIRE. IF PRESENT,
RED WIRE NOT USED.
RC-120
16

Additional thermostats are connected in parallel. They may be
connected in home-run or daisy chain configuration.
REMOTE DAY/NIGHT SETBACK SWITCHES
The thermostat can be connected to a remote system or remote
switch. A signal can be sent from the remote location to change the
thermostat temperature settings from the "DAY" setting to the
"NIGHT" setting. To use this mode, setup item 01 -
"Communications mode" must be set to 24.
Run a two conductor wire from the remote system or remote switch to
the thermostat location. Make the connections using supplied wire
splices - See Figure 8.
* Red and yellow wires are not used.
Insulate each using a small piece of tape.
Figure 8 - Hookup to remote Day/Night setback switch
OTHER SYSTEMS
For connections to personal computers, utility management systems,
and other automation systems, refer to connection diagrams provided
with personal computer software package or other system.
COMM
BLACK
GREEN
+12V
ANY SYSTEM WITH
A RELAY OR
12VDC OUTPUT
*
RC-120
17