Pressure differential bypass valve Herz model 4004 DN15

The Pressure differential bypass valve Herz model 4004 DN15 is designed to maintain stable differential pressure in hydronic heating and cooling systems by automatically diverting excess flow when pressure differentials exceed set thresholds. The compact DN15 size is suitable for small to medium installations and supports continuous, reliable operation of pumps and control valves. The valve construction is intended to reduce water-borne noise, prevent system imbalance and limit wear on circulating pumps and regulating components.

Advantages

This bypass valve provides automatic pressure regulation to protect pumps and sensitive control valves from excessive differential pressure. Its compact DN15 form factor allows installation in tight spaces while ensuring consistent hydraulic performance. The model 4004 reduces hydraulic noise and minimizes the risk of valve hunting and oscillation in closed-loop systems. Its mechanical design enables stable operation without electrical power, reducing complexity and maintenance needs.

Suitable for

• Hydronic heating systems in residential and small commercial buildings
• Closed-loop cooling circuits and fan coil units
• Protection of circulation pumps and modulating control valves
• Retrofit installations where space is limited

Key specifications

• Nominal size: DN15 suitable for small to medium pipework
• Function: automatic differential pressure bypass to maintain system balance
• Operation: mechanical, spring-loaded bypass mechanism
• Connection type: compact threaded connection for inline installation
• Application: compatible with hot water heating and chilled water systems

How to use

Install the Herz model 4004 DN15 in parallel to the control valve or in the return line according to hydraulic design to provide a bypass path when differential pressure rises. Ensure the valve orientation and threaded connections match the system piping and use appropriate sealing materials. Commissioning requires verification of differential pressure set point and observing system behaviour during normal and peak flow conditions. No electrical supply is required; adjust and test hydraulically during system start-up.

Usage recommendations

Place the valve close to the pump or control station to ensure effective pressure stabilization. During commissioning, monitor for proper bypass activation and verify that the valve reduces noise and prevents pump overload. Periodic visual inspection and flushing during scheduled maintenance are advised to avoid debris accumulation; follow local regulations and Herz installation guidelines for best results.