Honeywell T2798I2000 User Manual

Page 1 of 18 APHITEMPCON001-11-04
APPLICATION:
This standalone micro-controller based LCD temperature
controller provides proportional plus integral (P+I) and on/off
temperature control for commercial Heating, Ventilating & Air
Conditioning System such as Hydronic Heating, Air Handling
Unit, Heat Exchanger or Condensing Tower.
This controller has a modulating analog 2 to 10Vdc or 4 to
20mA output and a 2A on/off output to realize various optional
control functions including cool/heat changeover, heat/cool
sequence control, emergency interlocking and auto-alarming
control.
Table of Contents
Application………………………………………….1
Features…………………………………………….1
Specification………………………………………..2
Dimensions, Installation & Wiring Terminals..….3
Control Operation………………………………….4
Installer SetUp……………………………………..12
FEATURES:
• PI (proportional plus integral) control action
provides accurate, stable and comfortable
temperature control.
• Compatible with series 70 direct-coupled
damper / valve actuator like ML7161,
ML7174, ML7420 / ML7421series ML7425,
ML7984 series, N20010, S10010, M7410E
series, CN7505, CN7510 / CN72 series
CN7220 & CN7234 also VC79 series etc.
• Backlit LCD to display both setting and
measured value.
• Adjustable Zero Energy Band, On/Off
Differential, Proportional Band and
Temperature Offset.
• Analog output can be forced manually to be
convenient for installation & commissioning.
• Optional 2 to 10Vdc or 4 to 20mA direct
acting and reverse acting analog output.
• Selectable internal and external temperature
sensor.
• Wide temperature control range (-20 to 110
°C by using external temperature sensor) is
suitable for extreme temperature control such
as steam and ice water.
• Watch Dog Timer: to resume the controller
from hanging condition.
• Brownout effect to avoid malfunctioning and
care on power ON and power OFF.
• Pluggable terminal block allows pre-wiring
outside of the controller.
• Compact size and slim design provide
elegant and attractive modern style
appearance.

Honeywell T2798I2000 Specifications

General

Stages	2 Heat / 2 Cool
Input Voltage	24V AC
Output Type	Relay
Enclosure Type	Plastic
Dimensions	5.5 x 3.5 x 1.5 inches
Weight	0.5 lbs
Display	LCD
Wi-Fi Connectivity	No
Temperature Range	40°F to 90°F (4°C to 32°C)
Application	Residential
Operating Temperature	0°C to 50°C
Compatibility	Most HVAC systems
Power Source	24V AC

Summary

APPLICATION

FEATURES

Core Control Capabilities

Features PI control, backlit LCD, and adjustable parameters for precise control.

System Integration & Reliability

Includes actuator compatibility, manual analog output, Watch Dog Timer, and brownout protection.

SPECIFICATIONS

Product Identification & Performance

Covers model, control performance, inputs, outputs, and setpoint range.

Environmental & Operational Data

Details operating ambient, storage, accuracy, and enclosure specifications.

Configuration Parameters

Lists adjustable operating parameters like Zero Energy Band and Proportional Band.

DIMENSIONS

INSTALLATION

Mounting Recommendations

Guidance on controller placement for optimal temperature measurement and air circulation.

Installation Location Precautions

Advice on avoiding areas affected by draughts, ducts, or radiant heat.

CONTROL OPERATION

Input Configuration

Covers remote sensor and emergency input settings.

Output Functions

Details modulating analog and on/off digital output capabilities.

HEAT/COOL CHANGEOVER

Output1 Application

Suitable for 2pipe AHU, Zoning, or Hydronic Heating with manual changeover.

WIRING DIAGRAM

HEATING + COOLING SEQUENCE

Zero Energy Band Control

Explains sequence control using Z-Band for heating and cooling set points.

HEATING/COOLING LIMITATION

Output2 Temperature Limit

Details using Output2 for temperature limitation in heating or cooling modes.

STANDARD WIRING DIAGRAM

ACTUATOR WIRING DIAGRAMS

Wiring with ML-7984 Actuator

Illustrates connections for T279812000 with ML-7984 actuators, including dip switch settings.

Wiring with ML-7421 Actuator

Details wiring for T279812000 with ML-7421 actuators, showing terminal connections.

WIRING WITH M7410E ACTUATOR

WIRING WITH N10010/N20010 ACTUATORS

WIRING WITH VC-7934 ACTUATOR

INSTALLER SET-UP GUIDE

Initial Power-Up & Display

Describes the sequence upon powering the controller and initial display.

Set Point Adjustment

Details how to adjust the set point value using the up/down keys.

PARAMETER CONFIGURATION

Zero Energy Band Setting

Configures the Zero Energy Band for heating/cooling control.

Differential Setting

Adjusts the On/Off differential for control stability.

Proportional Band Setting

Sets the proportional band for modulating control accuracy.

Offset Setting

Allows adjustment of the temperature offset value.

MODE AND SENSOR SETTINGS

Mode Setting Configuration

Selects control modes like COOL, HEAT, C/H, H/C, C/AL, H/AL.

Sensor Setting Configuration

Configures the temperature sensor as internal (INT) or external (EXT).

ADVANCED SETTINGS

Reverse Action Setting

Configures output1 for normal or reversing action (10-2Vdc or 20-4mA).

Display Setting

Controls display mode between normal and percentage output.

Manual Operation Setting

Enables manual ON/OFF control of outputs.

FUNCTIONAL SETTINGS

F1 Integral Time Setting

Sets the integral time for output1, affecting response speed.

F2 Alarm Set Point Setting

Configures the alarm set point (F2) for temperature limit control.

DEFAULT SETTINGS

Parameter Default Values

Lists the default values for key parameters like Z-BAND, DIFF, P-BAND, and OFFSET.

Pre-setting Important Checks

Provides critical points to check before connecting power and setting parameters.