Model 400 HVAC Controller

A Comprehensive Monitoring & Control System for Telecom/Broadband Facilities.

Prevent short cycling of HVAC equipment

Up to 16 Model 400 HVAC Controllers can be networked to the TELSEC ESB2


T-Stat Product Matrix in PDF


The Model 400 Controller (PN #150966-5) is designed to work as a standalone HVAC control system or in conjunction with the TELSEC® ESB2 Environmental Controller to provide a comprehensive monitoring and control system for Telecom/broadband facilities.

Multiple HVAC units can be grouped by the area they serve to provide lead/lag/standby functionality per zone. HVAC systems with economizers can take advantage of Quest’s patented economizer control algorithm to maximize the amount of time outside air can be used to maintain the temperature in each zone. One outside air sensor can be shared with all Model 400 units. The Model 400 Controller is a convenient and reliable controller that provides the necessary redundancy for critical facilities while providing optimization that reduces energy consumption of the HVAC equipment.

Model 400 Features

  • Can be configured to control most HVAC systems such as single stage, two stage or heat pump systems.
  • Designed to work with existing HVAC economizer control modules or take direct control of the outside air damper.
  • Supports variable speed control of the supply air fan.
  • Powered from the HVAC’s 24VAC transformers.
  • Additional 24VDC power source supported.
  • Networkable to the ESB2 or any Modbus RTU controller.
  • Works in standalone mode if communications are lost.
  • LCD display for current operating mode
    and temperature readings.
  • Five button keypad for navigation to other status screens.
  • Default settings and configuration are settable through password protected screens.
  • All settings can be modified remotely through Modbus RTU.
  • Built-in zone temperature for ease of installation.
  • Additional zone sensor can be added for controlling based upon the average or high of the two sensors.
Up to 16 Model 400 HVAC Controllers can be networked to the TELSEC ESB2.


The Model 400 setpoints are field changeable via password.

Example Settings
Standalone mode - cool 1 on76
Standalone mode - cool 2 on78
Standalone mode - All cooling off74
Standalone mode - heat 1 on55
Standalone mode - heat 2 on53
Standalone mode - All heating off60
Standalone mode - fan operationAuto
Network mode - cool 1 on78
Network mode - cool 2 on80
Network mode - All cooling off74
Network mode - heat 1 on50
Network mode - heat 2 on48
Network mode - All heating off
Network mode - fan operationOn


  • Utilities/Telecommunication/Cable & Broadband – Remote Cabinets & Shelters
  • Data/Switching/Computer Centers/COs/Headends & Hubs


Model 400 Quest Part number: 150966-5

Part Number

Wall mount directly or standard single gang electrical box

Color: Quest white
Material: Two-piece thermal molded plastic enclosure. All wiring is done on the mounted base and the controller is pull-off.

Digital Inputs:(2) dry contact closures
Analog inputs: Temperature sensors (4) Thermistors sensor ± 1°F (0.5°C)4-20mA input (1) – HVAC Current Monitoring

Digital Outputs: (6) 30V AC max, 1 A continuous, 3A in-rush
Analog Outputs: (2) 0-10VDC

24VAC and 24VDC simultaneously

LCD Display
Type: Backlit LCD display
Display Area: 2 rows of 16 characters each

Five button directional arrows plus enter button

RS485, Modbus RTU

Operating Temperature: 0°C to 50°C; 32°F to 122°F
Storage Temperature: -30°C to 50°C; -22°F to 122°F
Relative Humidity: 0 to 95% non-condensing

5.32”W x 3.5”H x 1.5”D (135 x 89 x 38 mm)

0.5 lb (227 g)

1 year

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