T775 2000 Series

The Honeywell T775 Series 2000 are electronic stand-alone temperature controllers for commercial, agricultural, and hydronic heating applications that require remote sensing, switched relay outputs, proportional analog outputs, or staged sequencing from a single configurable controller. T775 Series 2000 controllers accept up to two temperature sensor inputs and provide switched SPDT relay outputs and 0-10V or 4-20 mA analog outputs depending on the model configuration, with PI and PID control available for modulating outputs. The T775 lineup includes standard models (T775A, T775B, T775M), a universal controller for non-temperature analog inputs (T775U), a dedicated boiler sequencing model (T775P), a staged relay sequencing model (T775L), and a relay expansion module (T775S) that allows the T775L and T775P to control up to 12 relays for staged applications. All T775 Series 2000 models feature a graphical interface with a large display and time clock scheduling capability.

T775A and T775B Standard Temperature Controllers

The Honeywell T775A and T775B are the standard single and dual sensor temperature controllers in the T775 Series 2000 lineup. The T775A2009 covers single temperature input with one SPDT relay and one included sensor. The T775B2032 provides two temperature inputs, two SPDT relays, and one included sensor for dual-zone or differential temperature control applications. Both models include the minimum off-time protection feature, time clock scheduling, and digital input for setback or disable control. The T775A series replaces several legacy Honeywell commercial temperature controllers including the T675, T7079, and T6031 series.

T775M Multi-Output Controllers

The Honeywell T775M is a multi-output T775 Series 2000 controller providing both switched relay outputs and proportional analog outputs for applications requiring modulating control of dampers, valves, or variable-speed drives. The T775M2006 provides two temperature inputs, two analog outputs, and one included sensor. The T775M2030 expands to four SPDT relays and two analog outputs with two temperature inputs. PI and PID control tuning is available on analog outputs, with adjustable integral and derivative times for precise control of modulating actuators. The T775M series is the correct specification for hydronic reset control or floating actuator applications where proportional output is required.

T775P Boiler Sequencing Controllers

The Honeywell T775P is a dedicated boiler sequencing model within the T775 Series 2000 family, designed for staging multiple boilers from a single controller with configurable temperature inputs and relay outputs. When paired with the T775S relay expansion module (part T775S2008), the T775P can control up to 12 relay outputs for staging applications. The T775P includes a digital output alarm configurable for minimum, maximum, or differential temperature conditions. The T775P is the correct specification for commercial multi-boiler applications where a single stand-alone controller manages the full boiler staging sequence.

T775S Relay Expansion Module

The Honeywell T775S2008 relay expansion module adds relay output capacity to the T775L staged sequencing controller and T775P boiler sequencing controller, with each T775S providing four additional SPDT relays. Using multiple T775S expansion modules with the T775L or T775P enables staged relay control of up to 12 relay outputs total from two independent heat or cool setpoints. The T775S mounts in a separate enclosure with dimensions of 8-5/32" high x 4-13/32" wide x 2-15/16" deep. The T775S is compatible only with the T775L and T775P controllers and is not a standalone control device.

How to Choose Honeywell T775 Series 2000 Controllers

The output type required by the controlled equipment is the first selection variable. Relay-only applications such as on/off boiler staging or pump control use the T775A, T775B, T775L, or T775P. Applications requiring proportional analog outputs for modulating valves, dampers, or VFDs use the T775M or T775R. Applications requiring both relay and analog outputs in the same controller use the T775M series.

The number of temperature sensor inputs needed determines whether a single-input or dual-input model is appropriate. Single-sensor applications use the T775A. Dual-sensor applications, including differential control and outdoor reset, use the T775B, T775M, or T775R. All T775 Series 2000 models use 1097-ohm sensors; the T775-SENS-OAT outdoor air temperature sensor is available separately for outdoor reset applications.

For multi-boiler staging or multi-zone relay sequencing, the T775L or T775P with T775S expansion modules is the correct configuration. Each T775S adds four relays, allowing expansion to up to 12 total relay outputs. The T775P includes boiler-specific features such as differential temperature alarm and is the preferred choice over the T775L for boiler applications.

For anyone asking whether the T775 Universal controller (T775U) can be used for pressure or humidity control: the T775U is configured to accept any variable analog input, not just temperature, making it suitable for pressure, humidity, or other process variable control applications where the T775's standard temperature-specific inputs are not appropriate.

FAQs

What types of outputs do Honeywell T775 Series 2000 controllers provide?
Honeywell T775 Series 2000 controllers provide switched SPDT relay outputs and proportional analog outputs (0-10V or 4-20 mA) depending on the model. Standard models (T775A, T775B) provide relay outputs only. The T775M series provides both relay and analog outputs. The T775P provides relay outputs with expansion capability via the T775S module. Analog output models support PI and PID control tuning, per Honeywell T775 product documentation on SupplyHouse.

How many relays can the Honeywell T775L and T775P control?
The Honeywell T775L staged sequencing controller and T775P boiler sequencing controller can control up to 12 relay outputs total when paired with T775S expansion modules. Each T775S module provides four additional SPDT relays. The T775L and T775P stage relays from two independent heat or cool setpoints.

What sensor type does the T775 Series 2000 use?
Honeywell T775 Series 2000 controllers use 1097-ohm sensors. Most non-NEMA 4X models include sensor 5002159-001 in the package. The T775-SENS-OAT is a 1097-ohm outdoor air temperature sensor available separately for outdoor reset or outdoor temperature monitoring applications.

What is the T775 Universal controller (T775U) used for?
The Honeywell T775U is a universal controller that can accept any variable analog input, including pressure, humidity, or other process variables, not just temperature. The T775U2006 provides two SPDT relays, two analog outputs, and two sensor inputs. The T775U is specified when the controlled application requires analog process variable input other than the standard 1097-ohm temperature sensor.

Does the Honeywell T775 Series 2000 support time clock scheduling?
Honeywell T775 Series 2000 controllers include a time clock scheduler and digital input capability for setback and output disable control, per T775 product documentation on SupplyHouse. The time clock scheduling allows operators to program setback periods for energy management without requiring a separate scheduling device. The digital input can be used to disable outputs based on an external signal.