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  • New item   Differential pressure switch | 20–200 Pa | differential 10 Pa | SPDT | 1.5 A (0.4 A) 250 V AC | IP54 | DPR-200K

    Differential pressure switch | 20–200 Pa | differential 10 Pa | SPDT | 1.5 A (0.4 A) 250 V AC | IP54 | DPR-200K

    Code: DPR-200K
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    Adjustable differential air pressure switch with a 20–200 Pa range, 10 Pa switching differential and SPDT contact 1.5 A (0.4 A) / 250 V AC. Ideal for fan monitoring, filter monitoring and electric duct heater airflow proving in HVAC systems.

  • Product description

    Differential pressure switch | 20–200 Pa | differential 10 Pa | SPDT | 1.5 A (0.4 A) 250 V AC | IP54 | DPR-200K

    DPR-200K is an adjustable differential air pressure switch for heating, ventilation and air conditioning (HVAC) systems. It compares the pressure at two points and switches its SPDT contact once the set pressure difference of 20–200 Pa is reached. It is a simple and reliable way to monitor fan operation, filter clogging or airflow through a heater.

    Key idea:
    A ventilation unit can appear to be “running” while no air is actually moving through it: the fan belt has snapped, the filter is clogged or the heat exchanger has frozen. DPR-200K detects this from the actual pressure difference and sends a signal to the controls – to switch off the electric duct heater, trigger an alarm indication or remind you to replace the filter. The low 20–200 Pa range suits residential heat recovery units and small to medium-sized ducts.
    Setting range
    20–200 Pa
    Switching differential
    10 Pa
    Contact
    SPDT, 1.5 A (0.4 A) / 250 V AC
    Protection / temperature
    IP54, −40…+85 °C

    Operating principle

    The switch has two pressure ports: P1 (+) is connected to the higher-pressure point and P2 (−) to the lower-pressure point. Both ports are connected to the duct with PVC tubing via the supplied plastic duct connectors with mounting flanges.

    Inside the switch, a diaphragm senses the pressure difference between P1 and P2. When the difference reaches the value set on the knob, a microswitch changes over the SPDT contact; when the pressure difference falls more than 10 Pa below the set value, the contact returns to its initial position.

    The switching point is set on site using the knob with a graduated scale – no pressure gauge is needed. A transparent cover protects the knob against accidental adjustment and ensures the IP54 degree of protection.

    Why choose DPR-200K?
    It turns airflow into a clear “yes / no” electrical signal, so the controls know whether the ventilation is really working and can protect the heater, fan or filter in time.

    Technical specifications

    Product type Differential air pressure switch
    Model DPR-200K
    Medium Clean air, non-flammable and non-aggressive gases
    Setting range 20–200 Pa
    Switching differential (hysteresis) 10 Pa
    Maximum operating pressure 5 kPa
    Accuracy ±15 %
    Contact type SPDT (changeover, 1 pole)
    Contact rating 1.5 A (0.4 A) / 250 V AC
    Closed contact resistance < 400 mΩ
    Pressure ports P1 (+) and P2 (−), outer diameter 6.0 mm
    Adjustment Knob with graduated scale, under a transparent cover
    Degree of protection IP54 (with cover fitted)
    Operating temperature −40…+85 °C
    Mounting position Vertical (any vertical orientation)
    Scope of delivery 2 plastic duct connectors with mounting flanges, PVC tubing, 4 mounting screws
    Compliance CE, Low Voltage Directive 2014/35/EU

    Main functions

    • Fan operation monitoring – confirms that the fan is actually producing airflow, not just receiving power.
    • Filter monitoring – when connected upstream and downstream of the filter, it signals when the pressure drop exceeds the set limit and the filter is due for replacement.
    • Electric duct heater protection – allows the heating elements to be interlocked when there is no airflow, preventing overheating.
    • Heat exchanger frost indication – a rising pressure drop across the heat exchanger can indicate icing.
    • Low 10 Pa differential – precise switching even in low-pressure residential heat recovery systems.
    • SPDT contact – both “normally open” and “normally closed” logic can be used, depending on the controller.
    • Adjustment without a pressure gauge – the switching point is set with the knob against a graduated scale.
    • IP54 and −40…+85 °C – suitable for duct mounting in unheated rooms and plant spaces in lofts.
    • Complete mounting kit – connectors, tubing and screws are already in the box, nothing extra to buy.

    Where is it used?

    • Residential and commercial heat recovery ventilation units
    • Air handling units with electric air heaters
    • Filter sections – for clogging monitoring
    • Inline duct fans – for airflow proving
    • Ventilation of server rooms and technical rooms
    • Kitchen hood and exhaust systems
    • Air side of heat pumps and air conditioners
    • Pressure cascade monitoring in cleanrooms and laboratories

    Use by role

    For ventilation installers.
    An affordable and reliable fan or filter monitoring device that can be installed in a few minutes using the supplied parts.
    For automation integrators.
    A volt-free SPDT contact wired directly to a PLC or controller digital input – for alarm or filter signals.
    For facility managers.
    Filters are replaced based on actual clogging rather than the calendar – fewer unnecessary jobs and lower energy losses.

    Practical example

    If the pressure drop across a clean supply air filter in a heat recovery unit is about 50 Pa and the manufacturer recommends replacing the filter at about 120 Pa, connect P1 upstream of the filter and P2 downstream, then set the DPR-200K knob to 120 Pa. When the filter becomes clogged, the contact changes over and the controller displays “Replace filter”. Once the filter has been replaced, the pressure drop falls and the signal clears automatically.

    Pros

    • Low 20–200 Pa range for residential and small systems
    • Low 10 Pa switching differential
    • SPDT contact – NO or NC logic
    • Adjustment without a pressure gauge
    • IP54, wide −40…+85 °C range
    • Mounting kit included

    Cons / limitations

    • On/off signal only – no pressure readout and no analogue output; for measurement choose a pressure transmitter
    • Accuracy ±15 % – suitable for monitoring, not for precise measurement
    • For higher pressures choose DPR-500K (50–500 Pa) or DPR-1000K (200–1000 Pa)
    • Not suitable for flammable or aggressive gases or liquids

    Safety and installation notes

    • ⚡ Before wiring the switch, isolate the control circuit supply and verify that no voltage is present.
    • ⚠ Do not exceed the contact rating of 1.5 A (0.4 A) / 250 V AC. Connect higher-power or inductive loads (contactor coils, valves, fans) via an interposing relay or contactor.
    • ⚠ Mount the switch vertically – in any other position the switching point may shift.
    • Always connect P1 (+) to the higher-pressure point and P2 (−) to the lower-pressure point. If they are swapped, the switch will not work.
    • Route the tubing without kinks and so that condensate can drain back into the duct rather than into the switch.
    • Locate the pressure tapping points in a zone of steady flow, away from bends and the fan – this prevents a pulsating signal.
    • Refit the transparent cover after adjustment – IP54 protection is only ensured with the cover in place.
    • Installation and wiring must be carried out by a qualified electrician or HVAC technician.

    Quick selection guide

    20–200 Pa
    Differential 10 Pa
    SPDT
    1.5 A (0.4 A) / 250 V AC
    IP54
    Max 5 kPa
    Suitable when you need to:
    • monitor fan operation or filter clogging up to 200 Pa;
    • protect an electric air heater from running without airflow;
    • provide a simple “yes / no” signal to a controller or alarm indicator.
    Check before use:
    • whether the required switching point lies within the 20–200 Pa range;
    • whether the current of the controlled circuit stays within 1.5 A (0.4 A) / 250 V AC;
    • where the higher-pressure (P1) and lower-pressure (P2) tapping points will be.
    Important reminder: a pressure switch does not replace the heater's safety thermostat (overheat cut-out) – it is mandatory as a separate device in any electric air heater.

    FAQ

    How do I connect the switch for filter monitoring?
    Connect P1 (+) upstream of the filter and P2 (−) downstream, then set the knob to the final pressure drop specified by the filter manufacturer.
    How do I check that the fan is running?
    Connect P1 to the pressure side downstream of the fan and P2 to the suction side, or leave P2 open to atmosphere, then set the switching point slightly below the normal operating pressure.
    Are the tubing and connectors included?
    Yes, the kit includes 2 plastic connectors with flanges, PVC tubing and 4 mounting screws.
    Does the switch display the pressure value?
    No, it is an on/off switch – it only changes over its contact at the set point; to measure pressure you need a differential pressure transmitter.
    Can a fan or contactor be connected directly?
    Loads up to 1.5 A (0.4 A) / 250 V AC can be connected directly, but higher-power and inductive loads should be switched via an interposing relay.
    Can the switch be installed outdoors or in an unheated loft?
    Yes, the switch operates at −40…+85 °C and provides IP54 protection when the transparent cover is fitted.

    Differential pressure switch DPR-200K | 20–200 Pa | SPDT | IP54

    DPR-200K is an adjustable differential air pressure switch with a 20–200 Pa setting range, 10 Pa differential and SPDT contact rated 1.5 A (0.4 A) / 250 V AC, designed for fan operation monitoring, filter monitoring and airflow proving through heaters in ventilation systems. IP54, −40…+85 °C and a complete mounting kit – a fast and reliable solution for heat recovery units and HVAC controls.

    Illustrative image may have been created using AI. The appearance of the product may differ slightly from the image shown. Please refer to the technical specification.

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