Coliter ® Straight Return Valve – 1.0 MPa, 0–90°C, with Drain Function for Hydronic Systems
NQ3008 Straight Return Valve – Brass Return Valve with Integrated Drain for Radiator and Underfloor Heating Circuits
The Coliter® NQ3008 Straight Return Valve is a high-quality brass return valve designed for balancing, isolating, and draining hydronic heating circuits in radiator and underfloor heating systems. It features a manual handwheel for precise flow adjustment and full shut-off, along with an integrated drain function that enables easy system maintenance, air venting, or winterization. Constructed from forged lead-free brass, it is rated for a nominal pressure of 1.0 MPa and operates reliably within a temperature range of 0°C to 90°C. The valve complies with ISO 228 (BSP parallel) threading standards and is available in two common sizes: 15×20 mm (G1/2") and 20×25 mm (G3/4"). Its robust design ensures leak-free performance, long service life, and seamless compatibility with standard radiator tails and manifold connections—making it ideal for residential and commercial heating installations.
Installation diagram
Product Description
| DN | G | DE | L | H |
| 15*20 | G1/2" | 20 | 95.5 | 26.5 |
| 20*25 | G3/4" | 25 | 100 | 29 |
Technical Specifications
Nominal Pressure: 1.0 MPa
Working Medium: Water
Working Temperature: 0℃ ≤ t ≤ 90℃
Pipe Threads: ISO 228
Product Inquiry
We will contact you within one working day. Please pay attention to your email.
Faq - Frequent questions
Introduction to Return Valve
Coliter®’s return valves are essential components for balancing and isolating return lines in hydronic radiator and underfloor heating systems. The series includes the NQ3001 straight return valve, NQ3002 angle return valve, and NQ3008 straight return valve with drain function—all featuring high-quality brass construction, PV10 (1.0 MPa) pressure rating, and operating temperatures up to 110°C. Designed with manual handwheels for precise flow adjustment and full shut-off, they enable system balancing, maintenance isolation, and easy air venting or drainage (on NQ3008). Compatible with standard radiator tails and manifold connections, these valves ensure efficient heat distribution, leak-free performance, and long-term reliability in residential and commercial heating installations.
