HERZ DN25 Differential Pressure and Static Balancing Valve Set
The differential pressure control valve operates with proportional control and functions without the need for any auxiliary energy. The required differential pressure can be adjusted within a range of 5–30 kPa. The set value can be clearly read from the indicator and securely locked in position.


The differential pressure reference value is factory-set to the minimum and can be readjusted to the desired value if required. A 1000 mm copper capillary tube is included in the scope of supply and is connected to the supply line together with a static balancing valve.


The differential pressure control valve features a compact design and a dezincification-resistant brass body. It is equipped with a 1" female threaded connection, pressure class PN25, and offers a flow range of 150–2000 l/h.


The differential pressure control valve is installed on the return line. The flow direction is indicated by an arrow on the valve body. It is recommended to install isolation ball valves upstream and downstream of the valve. The static balancing valve and the capillary tube must be connected to the supply line. Connection details are available on the product illustration pages.
Application Area
Differential pressure controllers are used to stabilize differential pressure in heating and cooling circuits, ensuring that heating or cooling consumers remain unaffected by dynamic fluctuations within the branch lines.
For presetting the differential pressure controller, the pressure loss ΔP of the system branch is used. The total branch pressure loss ΣΔP [kPa] is calculated using the following formula:


ΣΔP<sub>branch</sub> = ΔP<sub>branch</sub> + ΔP<sub>dP</sub>
where:
ΔP<sub>dP</sub> is the pressure loss of the differential pressure control valve. For optimal performance, a minimum ΔP<sub>dP</sub> value of 10 kPa is recommended.
Differential Pressure Adjustment
The valve is factory-set to the minimum value. Adjustment is carried out by turning the knurled nut. The differential pressure controller can be set in any installation position, and the selected setting is clearly displayed on the controller.


An example of differential pressure calculation and adjustment is shown in the product illustrations.