Features and Benefits

Programmable Solid State Controller

  • Balanced Use of Conditioning Equipment
  • Sequence the Operation of Six Air Conditioners
  • Ensures Maximum Efficiency
  • Independent Economizer Control

Alarms & Lockouts

  • High Pressure Alarm/Lockout
  • Low Pressure Alarm/Lockout
  • Low Temperature
  • High Temperature Stage 1
  • High Temperature Stage 2
  • Smoke
  • Low Voltage Loss

Dry Contact Alarm Outputs

  • Notification of HVAC Unit Failure
  • High/Low Pressure Lockout, Loss of Landline Power
  • Low Temperature
  • High Temperature Stage 1
  • High Temperature Stage 2
  • Smoke
  • Low Voltage Loss

Product Literature

Marvair CommStat 6 Product Data Sheet (Rev.10) (pdf - 2879 KB)

CommStat 6 HVAC Controller 

Our most comprehensive HVAC controller for air conditioners in a telecom shelter or enclosure.

Marvair CommStat 6 HVAC Controller

The CommStat™ 6 HVAC controller is designed for controlling up to six redundant air conditioners in an E-House or telecommunication shelter and is available in two configurations.

CommStat 6 4/8 - Controls up to four single stage or four 2-Stage air conditioners (8 Stages max.)

CommStat 6 6/12 - Controls up to six single stage or six 2-Stage air conditioners (12 Stages max.)

In addition to the control of the air conditioners, the CommStat 6 controller has multiple configurable outputs for remote alarms or notification.

The CommStat 6 controller is factory programmed with standard industry set points, but can be configured on site. Settings are retained indefinitely in the event of a power loss.

Master/Slave Modules
The CommStat 6 controller consists of multiple modules housed in a durable and attractive enclosure. Each module consists of a keypad/display and PC board. The CommStat 6 4/8 controller has one Master and one Slave module. The 6/12 version has one Master module and two Slave modules. Any settings to the Master module immediately take effect on the Slave module(s).
The CommStat 6 controller connects to each air conditioner with standard low voltage thermostat conductors.

Ease of Control and Configuration
Large, backlit LCD displays show the status of the system and provides a convenient user interface. Status LEDs indicate Heat, Cool, Power and the Lead Unit. When a fault is detected, an alarm LED illuminates and the LCD screen displays the fault. If multiple faults are detected, the display will scroll the faults across the screen.

The CommStat 6 controller is easily configured with four buttons. A Comfort button changes the temperature in the shelter for 90 minutes. After 90 minutes, the temperature reverts back to the programmed set points. A lead swap button alternates the lead and lag unit, allowing service techs to quickly check the operation of each unit.

For security, the keypad can be locked out to prevent unwanted changes to the set points. English, Spanish or French is selectable as the language shown on the display. °F or °C is selectable.

RoHS Compliant
The CommStat 6 controller contains no hazardous materials and is RoHS compliant.

Specifications / Features:

Thermostat Range:
  • Cooling: 65° - 95°F (18° - 35°C) in 1° increments.
  • Heating: 50° - 80°F (10° - 27°C) in 1° increments.
  • All stages ON differential: 2°F through 5°F
    (1° through 3°C) in 1° increments.
  • All stages OFF differential: 1°F through 5°F
    (1° through 3°C) in 1° increments. The 2nd stage differential is referenced to the 1st stage differential and the outputs will stage off as each stage’s differential is satisfied.
  • Changeover Differential between cooling and heating: Minimum of 3°F (2°C).
  • 3rd stage cooling Differential: 0°F through 7°F
    (0°C through 4°C) in 1° increments
Control Voltage:
  • The CommStat 6 controller is powered by a nominal 24 VAC and optional user provided backup 24 VDC or 48 VDC power supply. Should AC power be lost, the display, user interface and the alarm outputs remain functional. System outputs (Y, G, W, O and the Mixed Air Relay) will not be functional when 24 VAC is not present. If the control voltage is not present, the Low Voltage Loss alarm relay is energized.

Operating Range:
-40°F through 150°F
(-40°C through 66°C)

Minimum Voltage:
18 VAC

Maximum Voltage:
30 VAC

Ease of Installation
  • Wiring connection insensitive to phasing of the HVAC units.
  • Easy terminal connections for thermostat wire.
  • Remote temperature sensors insure accurate temperature readings.
Lead/Lag Operation
  • The CommStat 6 controller automatically alternates the lead unit for each cooling cycle.
Alarms: Dry contacts can be used for remote alarm or notification. Relays can be wired Normally Open (NO) or Normally Closed (NC). Most alarm relays can be reset by turning the CommStat 6 OFF and then ON OR the UP and DOWN buttons are held simultaneously for 4 seconds. Alarms can be reset provided there is no longer an input from the smoke detector. All alarms are functional when 24 VAC is applied to the board. If 24 VAC is not present, no alarms will be displayed unless DC power is present. If DC power is supplied to the board, the display is operational.
  • Low (Control) Voltage – activated if control voltage is not present.
  • Lockout – activated if any air conditioner is off due to either high or low refrigerant pressure lockout. If all the air conditioners or heat pumps are locked out, the Mixed Air Relay (MAR) will be activated on each of the air conditioners or heat pumps. This air conditioner or heat pump will go into the Ventilation mode, provided there is a call for cooling. (Note: The Mixed Air Relay is only on units with an economizer) If desired, the lockout alarm can be disabled by the user in the Configuration Set-up.
  • Low Building Temperature Alarm – Activated if the temperature in the building drops to the selected temperature. If the low building temperature alarm is activated, the LCD displays, “Low Building Temperature”.
  • First Stage High Building Temperature Warning – If the set point temperature is reached, the display will show, “First Stage High Building Temperature” on the LCD display.
  • Second Stage High Building Temperature Alarm - Activated if the set point temperature is reached, the display will show, “Second Stage High Building Temperature” on the LCD display.
  • Smoke Alarm – the contacts will be energized when the smoke detector inputs receive a signal from an external detector. All air conditioners are immediately shut down. A physical reset is required to clear the alarm in the manual mode. If auto reset has been selected, the alarm will reset after the user specified time (3-10 minutes).
  • Controller Fail Alarm - If the CommStat 6 controller does not function, but has power, all alarms are activated to indicate a failure of the CommStat 6.
  • AUX1 and AUX2 – Two auxiliary dry contact outputs that can be energized based upon AUX1 and AUX2 inputs. See AUX1-IN/AUX2 INPUT on page 4 of the product data sheet for complete description.

For detailed specifications, performance, and efficiency information, download the Product Data Sheet from the document list on this page.