EPH CONTROLS CDT2-24 Room Thermostat Instruction Manual

EPH CONTROLS CDT2-24 Room Thermostat Instruction Manual

Prior to setting the thermostat, it is neccessary to complete all required settings described in this section.

Factory default settings

• Contacts: Volt Free
• Temperature indicator: °C
• Switching diferential: 0.4°C
• In built frost protection: 5°C
• High and Low temp. limitation: OFF
• Blue backlight activated : for 10 secs after any button is pressed
• Keypad lock : OFF

Specifications & wiring

• Power supply : 24Vac 50Hz
• Power consumpti on: 8 VA
• Temp. control range: 5 … 35°C
• Ambient temperature: 0 … 50°C
• Contact rating: 7A 24Vac
• Dimensions: 84 x 84 x 30mm
• Temperature sensor: NTC 10K Ohm @ 25°C
• Switching difierential: Adjustable from 0.2/0.4/0.6/0.8/1.0˚C
• Frost protection: Only operational in stand by mode

Mounting

The mounting height should be 1.5 meters above the oor level.

The thermostat should be wall mounted in the room where the heating is to be controlled.

The place of installation should be chosen so that the sensor can measure the room temperature as accurately as possible.

Choose the mounting location to prevent direct exposure to sunlight or otherheating / cooling sources when mounted. The unit can beutted to:

1. Recessed conduit boxes
2. Surface mounting boxes
3. Directly on walls.

Installation

• Slacken the fastening screw on the bottom of the thermostat with a philips head screwdriver.
• The thermostat is hinged and can be opened 180 degrees.
• Mount the unit as described in section 3.
• Wire the thermostat according to the wiring diagram.
• Close the thermostat and tighten the fastening screw.

Wiring diagram

INTERNAL WIRING DIAGRAM CDT2-24 ****

If 24Vac output is required, terminals L & 2 must be electrically linked.

Frost protection

Frost protection is built into this thermostat, it is pre fixed at 5°C and is not adjustable.

It will only be activated when the thermostat is in the stand by mode and the room temperature reaches 5°C.

Button / Symbol description

Resetting the thermostat

It is necessary to reset the thermostat prior to initial use.
Press and hold the button for 5 seconds. dEL will appear on the screen.
Press the button on the side of the thermostat.

Keypad lock and unlock

To lock the keypad, press and hold the and buttons for 5 seconds. will appear on the screen. The keypad is now locked.

To unlock the keypad, press and hold the and buttons for 5 seconds. will disappear from the screen. The keypad is now unlocked.

High and Low temperature limitation

An upper and lower temperature limit may be chosen.
Press and hold the and buttons for 10 seconds. “Limit OFF” will appear on the screen.
Press the button to select “Limit ON” mode.
Press the button to confirm you wish to adjust the high limit temperature.
Press the and buttons   to select the high limit temperature.
Press the button to select the low limit temperature mode.
Press the and buttons to select the low limit temperature.
Press the button and the thermostat is ready for operation. “Limit” will appear on the screen.

To deactivate High and Low temperature limitation.
Press and hold the and buttons for 10 seconds. “Limit ON” will appear on the screen.
Press the button to deactivate this function. “Limit OFF” will appear on the screen.
Press the button and the thermostat is ready for operation.

Adjusting the switching differential (Normal)

Press the button once, Diff set will appear on the screen.
The factory default switching differential of 0.40C will appear on the screen.
Press the and   buttons to select the desired differential from 0.2 – 1˚C.
Press the button to return to normal operation.

Adjusting the setpoint temperature

Press the or   buttons to adjust the temperature setpoint.

Changing the thermostat mode

P1 – Normal On/Off mode
P2 – Delay Start mode (DS)
P3 – Time Proportional Integral Mode (TPI)

Press the ‘Reset’ button at the side of the thermostat.
P1 will appear on the screen.
Use the or buttons to change between P1 to P2 and P3.
Select P1 for normal operation.
Select P2 for delay start.
Select P3 for TPI – If P3 is selected you can press the button to choose the amount of cycles and then press the button to choose the proportional bandwidth. Press the **** ‘standby’ button to confirm. See section 16 for more information on TPI.

Normal control mode (On/Off )

When the temperature falls below the setpoint temperature, the ame symbol will appear and the thermostat will switch on. When the temperature rises above the setpoint temperature, the ame symbol will disappear and the thermostat will switch off.

Graph (14.1): On / O Control

Delay start control mode

Delay start is an energy saving mode.

When the delay start function is active the ame symbol will continuously ash on the screen. When in this mode the activation of the thermostat is delayed by a variable time depending on the current temperature, setpoint temperature and also the fall in temperature from when the delay start has activated. See graph (15.1) Delay Start Control.

Graph (15.1): Delay Start Control

The ame symbol will continue to ash until the thermostat activates.
When activated the thermostat will allow the heating system time to reach
the setpoint and delay start will remain inactive until it reaches this setpoint.
Delay start can be reactivated by:
Lowering the setpoint below the current temperature, pressing the ‘standby’ button to set the temperature, then raising the setpoint above the zone temperature within 6˚C of the setpoint.

The heating will be delayed as per the line on the graph.

If the difference between the actual temperature and the setpoint is 10C the thermostat will delay starting for circa 40 minutes.

If the difference between the actual temperature and the setpoint is 30C the thermostat will delay starting for circa 24 minutes.

If the difference is 60C or more, the heating will be switched on immediately.

The time delay will change if the temperature drops from the original calculation.

To deactivate Delay Start, see section 13.

Time Proportional Integral Mode (TPI)

When the thermostat is in TPI mode and the temperature is rising in the zone and falls into the Proportional Bandwidth section, TPI will start to afiect the thermostats operation. The thermostat will turn on and o as it gains heat so that it doesn’t overshoot the setpoint by too much. It will also turn on if the temperature is falling so it doesn’t undershoot the setpoint which will leave the user with a more comfortable level of heat.

There are 2 settings that will affect the thermostats operation:

1. The Number of Heating Cycles Per Hour
   The Proportional Bandwidth

CyC – Number of Heating Cycles per Hour:

This value will decide how often the thermostat will cycle the heating on and off when trying to achieve the setpoint temperature. You can select 2/3/6 or 12.

Pb – Proportional Bandwidth:

This value refers to the temperature below the setpoint at which the thermostat will start to operate in TPI Control. You can set this temperature from 1.5˚C to 3.0˚C in 0.1˚C increments.

TPI Control

Example – Program 1 on the thermostat is 21°C for 06:30am and the room temperature is 18°C. The thermostat will start the heating at 06:30am and the heat will start to increase then but will switch itself off before it reaches temperature and allow the room temperature to increase naturally – this cycle may begin again if the thermostat isn’t reaching temperature.

References

• Home Page - EPH Controls
• Home Page - EPH Controls

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