Plumbing fitting DANFOSS 003L0126 — return valve RLV-S 20 straight, 3/4" connection

DANFOSS 003L0126 is a straight return valve RLV‑S 20 with a 3/4" connection designed for use in heating and hydronic systems. Supplied as a single unit, this compact plumbing fitting allows controlled return flow in boiler and radiator circuits and is intended for installations where a straight-line valve body and reliable flow regulation are required.

Advantages

The RLV‑S 20 straight return valve provides stable return flow control with a compact straight-line design that simplifies installation in confined spaces. Constructed to meet typical industry durability standards for plumbing fittings, it offers straightforward integration into residential and commercial hydronic circuits and is supplied ready for connection with a 3/4" threaded interface.

Suitable for

• Residential central heating return lines
• Commercial boiler return circuits
• Radiator and convector return connections
• Hydronic loop systems requiring a compact straight valve

When it may not be suitable

This valve may not be suitable for systems that require angled or angle-type fittings, where space or piping orientation prevents a straight inline connection. It may also be inappropriate for systems with connection sizes other than 3/4" or where additional integrated features (such as built-in strainers, sensors, or motorized actuation) are required.

Key specifications

• Valve type: straight return valve (RLV‑S 20)
• Connection size: 3/4" threaded inlet/outlet
• Application: heating and hydronic return lines
• Unit supplied: single piece

How to use

Install the RLV‑S 20 in the return pipe of the heating circuit in the straight orientation, ensuring compatible 3/4" threaded connections and appropriate sealing (thread tape or sealing compound) as per installation practice. Tighten to recommended torque for the system piping material, then purge air from the system and check for leaks. Adjust system balancing and flow rates according to the hydronic design and commissioning procedures applicable to the installation.

What to consider before purchase

• Verify the connection diameter and thread type on the existing piping is 3/4" and compatible with the valve.
• Confirm the straight valve body fits the available space and piping orientation.
• Ensure the valve functional characteristics meet system flow and balancing requirements.

Usage recommendations

Use appropriate sealing materials on threaded joints, perform a pressure and leak test after installation, and follow local regulations and manufacturer guidance when integrating the valve into heating and hydronic systems.