Differential pressure controllers & flow controllers / limiters

A combined differential pressure controller and flow controller (PQ) consists of two independent differential pressure controllers and a flow restrictor (manual balancing valve) integrated in one valve body.

This device has two functions:

1) A differential pressure controller maintains fixed differential pressure over the flow restrictor (flow control). This ensures automatic flow limitation, independent of pressure variations in the system.

2) A differential pressure controller maintains constant differential pressure over motorized control valves or over the entire loop.

This is the best solution for the district heating utility as it enables both variables (maximum flow and differential pressure) to be set independently of the consumer’s heating control system. Especially when the subscriber station is owned by the consumer, the utility has no influence over flow limitation at the consumer’s end of the system.

This enables the district heating utility to control the flow available for each consumer as well as the differential pressure control at the substation. This allows efficient network balancing.

Another solution is the PB controller, which consists of one pressure controller and a flow restrictor (manual balancing valve). The PB is used in systems where independent flow and differential pressure are not required.

Differential pressure and flow controllers in district heating or cooling systems (variable flow)

Balance your network, save energy and improve end user comfort by hydronic balancing and control of district energy networks.

Features and benefits

Eliminates pressure variations and provide optimum operating conditions with improved temperature control quality

Made for demanding systems, resistant to corrosion, cavitation and dirt

Connected system is protected against pressure surges, fluctuations, cavitation and noise

Selection tool

Application tool


Can I limit a max flow with a differential pressure regulator?

Yes you can. Open the control valve fully and set the max flow by adjusting the differential pressure. You can also calculate the appropriate differential pressure, but you need to know the exact capacity of the control valve.

We design an installation and need lengths of valves from a project specification.

We produce valves with a standard length. You can also find the measures in our datasheet or download 2D and 3D CAD drawing models from our product presentations. Please go to our product catalog where you will find links to documentation and drawings - follow the below link.

We have installed a DN125 differential pressure controller, but found out that we need a bigger setting range. Do we need to order a new pressure actuator?

No, you do not need to change the pressure actuator. It will be sufficient to replace the setting spring only. Please contact your local sales or technical support for further instructions.

I am installing a AFPQ controller. I do not know how to connect impulse tubes?

Please use the instructions shipped with the product or open the online version of it by clicking the link: http://heating.danfoss.com/pcmpdf/vicag25v%20%20afpq,vfq.pdf


Case studies