Industrial / Valves
Danfoss CTR 20 Electric 3-Way Valve
Installation and service guide for the Danfoss CTR 20 electric 3-way valve. Includes technical specifications, brazing and welding procedures, electrical connection details, and maintenance instructions.
Table of contents
Manual images
Click an image to enlargeQuick guide from the manual
The Danfoss CTR 20 electric 3-way valve is delivered in a half-opened position, which is required for brazing and welding. Important: Do not connect the valve directly to an AC/DC power source; it must be connected to an appropriate controller or driver. Do not operate the valve while assembling or disassembling.
Technical specifications
- Main application: Heat reclaim
- Refrigerant: R44 (contact Danfoss for others)
- Ambient temperature: -40 °C to 60 °C (-40 °F to 140 °F)
- Fluid temperature: 0 °C to 150 °C (32 °F to 302 °F)
- Max working pressure: 140 Bar / 2030 psig
- Stepper motor type: Bipolar
- Phase Current: 100 mA RMS / 141 mA Peak
- Coil resistance: 52 Ohm ±10% (25 °C)
- Total full steps: 6600
- Step rate: 75 stp./sec.
Flow direction
The valve supports two flow configurations:
- A: 1 in, 2 outs
- B: 2 in, 1 out
Mounting and installation
The valve can be mounted in various orientations. Do not disassemble the valve before brazing or welding. Ensure the valve remains in the middle position during these processes.
Brazing
- Max temperature: 700 °C / 1300 °F
- Keep valve body below 75 °C / 167 °F
- Use recommended filler metals (e.g., Silver-Flo 55 or 56). Do not use filler metals containing Phosphor (e.g., BS: CP 1 / DIN L-Ag 15P).
Welding
- Max temperature: 75 °C / 167 °F
- Recommendation for TIG welding: Use Argon shield gas, approximately 60A power, and 2 mm thick stainless steel alloy material.
Electrical connections
The valve uses an M12 connection. Pinout configuration:
- A1 and A2: Coil I
- B1 and B2: Coil II
Service and maintenance
If service is required, a service kit (Code no. 027H7248) is available, containing 3 O-rings (White, Red, Yellow). Use a 72 mm spanner to unscrew the big nut. Ensure the fixing pin is correctly aligned in the gap during reassembly. Max torque for the nut is 130 Nm / 95.9 ft-lbf.
Manufacturer information
Danfoss A/S
Practical help
Common problems
Valve not operating correctly
Ensure it is connected to an appropriate controller/driver, not directly to an AC/DC power source.
Leakage after brazing/welding
Ensure the valve was not disassembled before brazing/welding and that the valve body temperature did not exceed 75°C.
Before use
- Verify the valve is in the half-opened position (as delivered).
- Ensure the controller/driver is compatible with the bipolar stepper motor.
- Check that the refrigerant is R744 (contact Danfoss for others).
- Prepare brazing/welding equipment with appropriate temperature controls.
- Ensure the fixing pin is aligned during any reassembly.
Specs in practice
- Phase Current
- 100 mA RMS / 141 mA Peak.
- Coil resistance
- 52 Ohm ±10% at 25°C.
- Max working pressure
- 140 Bar / 2030 psig.
- Ambient temperature
- -40°C to 60°C.
Images and diagrams
- Flow direction A: 1 in, 2 outs.
- Flow direction B: 2 in, 1 out.
- Electrical connection: M12 connector with A1/A2 (coil I) and B1/B2 (coil II).
Model compatibility
- Designed for R744 refrigerant; contact Danfoss for other refrigerants.
- Requires an appropriate controller/driver; do not connect directly to power.
Manual page author
Michael Turner
Technical manual editor
Reviews PDF manuals for structure, safety notes, and practical product details so readers can find the right information quickly.