Paxton TC 204 User Manual

ver. 1.32-01

TC 204 Heating Controller

The TC204 is a multi-purpose heating controller with built-in programs for different types of heating systems.

General Data

Power requirement 24 volts ac, 25 va
Inputs 3 10k ohm ntc thermistors
1 digital
Outputs 3 digital
2 analog 0 - 10 volt dc

This manual covers outdoor reset of hot water heating systems using a mixing valve and a 3-point
floating actuator. For other applications see the expanded manual at www.paxtoncorp.com

Notes to the installer:

1. Program #1 - Outdoor reset control using a mixing valve, is the default program.

2. All defaults in program #1 will work in most cases.

3. Connect all sensors, the actuator wires and power supply. Set time & date (page 9)
and let the system stabilize, before making any program changes.
Nothing else needs to be done in most cases.

Wiring

The diagrams show ESBE #62E (Paxton VM62) & 92-2M (Paxton VM92) valve actuators . These are 3-wire
floating, 24 volt ac valve motors which fit ESBE 3-way & 4-way valves.
VM62 actuators are used with valve sizes 1/2” through 2”: VM 92 actuators are used with valve sizes 2 1/2” - 6”.

Actuators of this type have a common wire. Voltage applied between the common and one of the remaining wires
drives the valve open and voltage between the common the the remaining wire drives the valve closed. If no volt­age is applied to either terminal the valve stays in place.

Other valves with different floating actuators may be used provided the voltage is 24 volts and the current draw
of the actuator does not exceed the capacity of the TC204 (25 VA). If these 2 conditions are not met the actuator
must be operated through intermediate relays.

Programs

There are eight programs in the TC204. This manual is for Program No.1 which is the default program.

Some not frequently used functions are not covered in this manual. Instructions for these as well as for all other
programs are available at:
www.paxtoncorp.com

Other programs provide outdoor reset by modulating valves that accept a 0 - 10 volt dc signal, outdoor reset by
direct boiler control, zone control without outdoor reset, and outdoor control of steam heating systems.

Program No. 1

Program 1 is Supply Water Temperature Control using a 3-point floating valve actuator. The control mode can be
Outdoor Reset with or without a room sensor, or direct control by room temperature only.

The supply temperature sensor must always be installed.
Outdoor reset is automatically initiated if the outdoor temperature sensor is installed.
Room temperature control is automatically initiated if the room temperature sensor is installed.
Additional functions are Pump Control, Auxiliary Output, and Return Water Low Limit (see page 8).

Temperature Sensors

The supply water and outdoor air temperature sensors are included with the TC204. A room temperature sensor
is optional. A room sensor is also built into the TC204, but to use it the TC204 must be installed in the controlled
space.

1

This comes in the package:
TC204 Controller mounted on a standard

4” x 4” electrical box
1 Outdoor Sensor
1 Supply Water Sensor
2 Cable Connectors (inside the electrical box)
1 Instruction Manual

Provided by installer:

120/24 Vac Transformer, 25 - 40 VA

Installation:

Remove the two screws in the corners of the 4” x 4” box
and lift off the cover. The controller is secured to this cover.
Set aside the 2 cable connectors located inside the box.

Install the box on a wall near the mixing valve or boiler,within
reach of the actuator cable. Or inside the mixing station
enclosure if there is space available.

Remove 1 or 2 knockouts and insert the cable connector(s).
Run the power supply, sensor, and output wires into the box.

The TC204 is connected to an external terminal
board secured to the under-side of the 4” x 4”
cover. This simplifies field wiring as there is no
need to open the controller itself.

The controller is pre-programmed with defaults
that match most heating systems in the northern
States & Canada. Typically no other adjustments
are needed but are easy to do, following instruc­tions in the operations manual.

Let the system stabilize before making
changes to control parameters.

Notes:

The TC 204 can be removed from the steel box cover and the external terminal board for
installation directly in an occupied space.

Loosen the connector on the circuit board and then the center screw under the lid of the controller.
Pry off the front of the controller and remove the two screws holding the terminal board.

For wiring of other applications, such as direct control of boilers in sequence, see the manuals on
our website www.paxtoncorp.com.

2

Outdoor Reset Control with
the VM62 Actuator.

Black
(counterclockwise)

1

10

11
12

2
3
4

Brown
(Clockwise)

Blue
(Common)

VM62 Actuator

5
6
6
7

Supply Water Sensor

Room or Return Sensor
(Optional)

8
9

6

5
6

24 Volts ac Power
25 va minimum

If the valve turns in the wrong
direction, reverse the brown &
black wires on the VM62 actuator

Sensor wires can be lengthened
with thermostat wire to maximum
250 feet.

Outdoor Sensor

10

11
12

Relay 24 vac coil
spst no

1
2
3
4
5
6

N

6
7
8
9

Pump

6

Line

Pump Control

5
6

3

1
2
3
4
5
6
6
7
8
9

10

6
11
12

5

6

N L1 L1

VM92 Actuators

Note:
The 2 terminals marked L1 are not the
same.
The left one drives the actuator clock­wise and the right one drives the actuator
counter-clockwise.
Output 2 on the TC204 increases heat.

10

11
12

1
2
3
4
5
6
6
7
8
9

6

5
6

1. Output to actuator – Less Heat

2. Output to actuator – More Heat

3. Pump start/stop (use external relay)

4. input for remote operation

5. Output to actuator 24 Vac

6. Common

6. Common

7. Return water or room sensor (optional)

8. Supply water sensor (must be used)

9. Outdoor sensor

10. Auxiliary output 10 Vdc

6. Common

11. ModBus A+ communication

12. ModBus B- communication

5. 24 Vac Power supply (hot side)

6. 24 Vac Power supply (common)

Always use this pair of ter­minals for the power input.

4