HVAC / Thermostats & Controls
Installation Guide for Danfoss RT Series Thermostats
Comprehensive installation, wiring, and adjustment guide for Danfoss RT series thermostats, including models RT 9E, RT 14E, RT 101E, RT 107E, and RT 123E. Covers safety requirements for explosive atmospheres, mounting procedures, and...
Table of contents
Quick guide from the manual
This document provides installation and operational instructions for the Danfoss RT series thermostats (RT 9E, RT 14E, RT 101E, RT 107E, RT 123E). These devices are designed for use in refrigeration systems and must comply with specific Ex installation standards (EN 60079-14). Key tasks include proper cable gland assembly, correct electrical wiring, and precise temperature adjustment using the main knob and differential nut.
Installation
RT units can be mounted in any position. Use the provided mounting holes for installation. If installing outdoors, ensure the unit is protected against rainfall. The temperature bulb must be fixed to the wall using the bulb holding bracket. For installation in water or brine tanks, use a capillary stuffing box or a bulb pocket.
Cable Gland Assembly: A Pg13.5 cable gland is included in a separate bag. It must be assembled to ensure the enclosure meets IP66 (automatic reset) or IP54 (external reset) ratings. If the gland is not used with a cable, a metal blinding must be installed.
Electrical Connection
Refer to the wiring diagram (Fig. 5) for connections. Ensure the earth terminal is connected to the earth. The cable diameter must be between 6 and 14 mm, with a minimum wire dimension of 0.75 mm².
- START: Make
- STOP: Break
- DIFF: Differential
Adjustment
The thermostat is adjusted using the main knob and the differential adjusting nut:
- Range Setting: Rotate the main knob while reading the main scale to set the minimum actuating temperature.
- Differential Setting: Rotate the differential adjusting nut according to the specific nomogram for your model (Fig. 3).
- Calculation: The maximum actuating temperature is the sum of the temperature setting and the differential.
Turning the main knob moves both the maximum and minimum actuating temperatures. Turning the differential nut only alters the maximum actuating temperature.
Safety Requirements
The RT-E series is intended for use in potentially explosive atmospheres. Adhere to the following:
- The system must comply with EN 60079-14 and local directives.
- Use only with certified Ex ia barriers to limit voltage and current.
- Ensure the enclosure is locally bonded to earth to prevent electrostatic charge accumulation.
- Do not allow cables to contact sharp edges; ensure adequate stress relief.
- Keep cycle frequency low to prevent fatigue failure on bellows.
- Power must be switched off before maintenance or opening the unit.
Manufacturer information
Danfoss A/S
Practical help
Common problems
Electrostatic charge accumulation
Ensure the external metal work of the enclosure is locally bonded to earth.
Cable stress or damage
Use adequate stress relief on the cable to prevent pulling forces from reaching the terminal.
Fatigue failure on bellows
Keep the cycle frequency of the switch as low as possible and minimize vibration levels.
Thermal ignition risk
When media temperature exceeds 80 °C, ensure the temperature does not cause thermal ignition on parts between the media and the enclosure.
Before use
- Verify the thermostat model is suitable for the required temperature range.
- Ensure the installation area complies with Ex installation standards (EN 60079-14).
- Check that the cable diameter is between 6 and 14 mm.
- Confirm the use of a certified Ex ia barrier for the input parameters.
- Ensure the earth terminal is connected to the earth.
Specs in practice
- Permissible ambient temperature
- -20 to 65 °C
- Contact load
- Max 100 mA, 30 V AC/DC; Min 1 mA, 5 V AC/DC
- Wire dimension
- Minimum 0.75 mm²
- Enclosure rating
- IP66 (automatic reset) or IP54 (external reset) when gland is correctly assembled
Images and diagrams
- Fig 1: Internal view of the thermostat mechanism.
- Fig 2: Assembly instructions for the Pg13.5 cable gland.
- Fig 3: Nomograms for setting the differential on different models.
- Fig 4: Bulb fitting instructions for tank installation.
- Fig 5: Electrical wiring diagram showing Start, Stop, and Differential connections.
Model compatibility
- Must be used with a certified Ex ia barrier satisfying the input parameters.
- Not for use with sharp-edged cable entries without proper protection.
- Maximum media temperature on switches with 2m or longer capillary tube is 300 °C.
Manual page author
Emily Carter
User documentation editor
Prepares concise manual descriptions and highlights the most useful setup, operation, and maintenance information for readers.