SPECIFICATIONS/FEATURES FOR BASIC CONTROLLER
MC4000 Basic Controller
•Input power: 18-32 VAC, 60/50Hz, power is supplied from A/C #1 and/or A/C #2
•Isolation circuitry: no line or low voltage phasing required
•Backup power: connection for -24 VDC or -48 VDC (-20 to - 56V) maintains microprocessor operation, front panel indication
&alarm relay operation during commercial power outages. •Digital display: 4-character LCD
•Temperature display: F or C
•HVAC outputs: Form A (NO) relays (1A @ 24 VAC) •Cooling control stages:
2 for each A/C unit (4 total) when configured for economizers
1 for each A/C unit (2 total) when configured for no economizers
•Heating Control stages:
1 for each A/C unit, 2 for each heat pump if so configured
•Dehumidification circuit: requires optional humidity controller as input signal
•Operating temperature range: 0 to 120F (-18 to 49C)
•Storage temperature range: -20 to 140F (-29 to 60C)
•Temperature accuracy: +/- 1F from 60-85F (16-30C)
+/- 1% outside 60-85F
•Lead/lag changeover time: 0 to 30 days
•Timing accuracy: +/- 1%
•Inter-stage time delay: 10 seconds between stages •Inter-stage differential:
Stage 1 to 2 - Range 2-6F, default is 4 Stage 2 to 3 - Range 2-3F, default is 2 Stage 3 to 4 - Range 2-3F, default is 2
•On-Off differential: 2F (1C) is standard, 4F (3C) when “excessive cycling” mode is enabled
•Cooling set point range: 65 to 90F (18.3 to 32.2C) •Comfort setting-Cooling 72F (22C), Heating 68F(20C), for 1 hour •Dead band (difference between cooling and heating set points): 2F to 40F (1.1C to 22.2C)
•Fire/smoke interface: standard NC circuit jumper, remove for connection to building system control, shuts down both A/C units immediately
•Memory: EEPROM for set point and changeable parameters (maintains settings on power loss)
•Space temperature sensors: 1 local is standard, will accept up to 2 optional 25' remote sensors, Bard part number 8612-023. When multiple sensors are used, temperatures are averaged •Controller Enclosure: 20-gauge pre-painted steel, 9.25"W x 13.50"H x 3.00"D, hinged cover, thirteen (13) .875" diameter electrical knockouts
•LEDs for basic controller: Lead unit, Cooling stages 1 through 4, Heating Stages 1 – 4, Dehumidification operation •Six (6) Push-button controls: On/Off switch-Change lead unit-Increase & Decrease set points-Program/Save-Comfort.
MOUNTING THE CONTROLLER
Included in the controller carton is the controller and installation instructions.
The controller should be installed on a vertical wall approximately four (4) feet above the floor-away from drafts & outside doors or windows. Four (4) mounting holes are provided for mounting to the wall and 7/8" holes for conduit connections are provided in both the base, sides & top of the controller.
TEMPERATURE SENSORS
The standard (local) temperature sensor has 12" leads and comes installed from the factory.
A secondary sensor is located internally on the main controller board and serves as a reference and back-up sensor to the local sensor. Any differential of +/- 12F between the on-board and local sensor will cause the controller to use the local sensor as its point of reference. If the differential is greater than 12F then the controller will check to determine the on-board sensor is reading a temperature that is between the SP (set-point) plus 12F and the SP minus the DB (dead-band) minus 12F. If it is the on-board sensor will become the valid sensor reading and the controller will ignore the local sensor reading. If it is not then the controller will still use the local sensor reading. This is to add additional level of operational capability in the rare event the local sensor fails. If the controller is operating in this mode it is indicated by the lower left decimal point flashing in the display. Note: for purposes of testing when the local sensor is manually driven higher or lower by applying warm or cool water to the probe the on-board sensor is inhibited for the first
30-minutes following power up, or when power is cycled off and back on.
The controller is designed to accept 1 or 2 additional sensors and those have 25-foot leads. The Bard part number for the optional sensor with 25-foot leads is 8612-023. These can be installed as required in the structure to address hot spots, barriers to airflow, etc.
It is recommended that the sensor lead wires be installed in conduit for protective purposes.
If alarm boards are utilized, the highest reading of any connected sensor will be used for high temperature alarm and the lowest reading sensor will be used for low temperature alarm.
NOTE: All sensors are polarity sensitive. The copper lead must connect to terminal CU, and the silver lead to AG. Sensors are solid state, not RTD. Use only sensors supplied by Bard. Sensor leads can be extended up to 200 feet. Use 18-gauge twisted pair with soldered connections.
TEMPERATURE SENSOR LOGIC
The standard local (LSEn) sensor monitors the temperature at the controller location. If this is the only sensor connected, it will control the temperature read-out, the space (building) temperature, and also be used for Low and High Temperature alarm functions.
If one or more REMOTE sensors are installed and connected (Rem 1 or Rem 2), the temperature read-out will display and the building will be controlled to an average of all connected sensors. If there is more than 10F difference from the highest to the lowest connected sensor, the actual control will be governed by the hottest sensor for cooling and the coldest sensor for heating.
If multiple temperature sensors are used, the High and Low temperature alarms will be governed by the average of the connected sensors.
