GRUNDFOS - FLANGE KITS FOR UNION MOUNTED PUMPS (Models, UPS15-35SUC/LC/DT, UPS15-55SUC/LC/DT) 3/4" bronze union isolation valve set (compression) - 519851

The Grundfos 519851 Bronze Union Isolation Valve Set is a premium circulator pump accessory designed for GU125 union-mounted Grundfos UP and UPS pumps. Featuring durable bronze construction and a 3/4 in compression connection, this isolation valve set allows installers to quickly isolate the circulator during maintenance or replacement without draining the entire hydronic system. The integrated quarter-turn shutoff valve simplifies servicing while minimizing system downtime. Engineered for residential and light commercial hydronic heating applications, the corrosion-resistant bronze body provides long service life, dependable sealing, and compatibility with potable and closed-loop heating systems.

Cross References

• Grundfos — 519851
• Grundfos — 3/4 in GU125 Bronze Union Isolation Valve (Compression)
• Grundfos — GU125 Union Isolation Valve Fitting Set

Usage

The Grundfos 519851 is used with GU125 union-mounted circulator pumps in hydronic heating systems. Installed between the pump and the system piping, the built-in isolation valve allows the circulator to be removed or serviced without draining the entire boiler loop. The compression connection provides a secure mechanical connection to copper tubing while the union fitting enables quick pump removal, making it ideal for boiler systems, radiant heating, fan coil units, and other closed-loop HVAC applications.