PIR or HF sensor: selection according to the room and controls

A motion or presence detector is selected by detection principle, room geometry and control interface together. Neither the label “HF” nor the word “presence” is enough to predict exactly what the specific model will detect. For a useful shortlist, first describe the space and desired action, then compare the technical data.

In motion and presence detectors , start with this task, rather than the longest advertised range. A long corridor and a room with several workstations raise different questions. Even with similar areas, their shapes and the zones you want to cover may differ.

What is the difference between PIR and HF

In its technical overview, STEINEL describes PIR as passive infrared technology. It detects changes in infrared radiation from warm objects without emitting any itself. This explains the principle, but does not automatically provide the sensitivity, range or operating conditions of every PIR model.

HF sensors emit high-frequency waves and analyse reflected signals to detect movement. This is a different principle. It does not imply that all HF devices have identical capabilities or that each reliably detects a stationary person under every condition.

The first comparison column can therefore be "technology", but it should be followed by separate columns for exact model, described zone and intended use. If the technical description does not address your scenario, the PIR or HF abbreviation alone does not fill the gap.

With HF, also check the desired zone's boundaries

STEINEL states that HF detection can pass through certain materials, such as glass or lightweight partition walls. The key word is “can”. This does not mean penetration through every wall and does not define a universal distance for all structures.

The practical implication for selection is to describe what lies immediately outside the desired area. If the room adjoins a corridor behind a lightweight partition, include this in the specification for checking the specific model. Assume neither that the partition necessarily blocks detection nor that the sensor will necessarily detect everything behind it.

Also note glass partitions and adjacent spaces. This inventory is not an installation diagram. It helps focus comparison on information about limiting the area and the application of the selected sensor instead of relying on a general promise of long range.

Coverage shape has its own role

A specific example is STEINEL Dual HF KNX 059477. The manufacturer describes two detection directions along the corridor and targeted limitation across it to its width. The example shows why the area's shape is an essential part of selection.

These characteristics apply to the stated model. They do not justify concluding that every HF sensor is for corridors or that every similar housing limits the zone identically. Compare each exact reference's coverage drawing or description.

For a corridor, record its length, width and adjacent openings. For a room, describe the locations that must fall within the area and those you do not want included. Then look for a match in the documentation. A general value in metres alone does not describe all these relationships.

“Presence” does not name a single technology

In its overview, STEINEL considers TruePresence separately from general PIR and HF technologies. Seeing "presence" in a name is therefore insufficient to assume a particular detection method or level. Seek the exact product's description and intended use.

This is especially important when the task involves prolonged occupancy with little movement. Describe this scenario explicitly instead of leaving it implicit. Then check what the manufacturer states for the model being considered. Do not transfer the characteristics of one specialised technology to all items in the presence detectors category.

The same approach also applies in reverse: the presence of specialised technology in a brand's catalogue does not prove that it is needed for every passage through a room. Selection follows the described task, rather than a ranking of abbreviations from “basic” to “best”.

Two scenarios deserving separate answers

In the first scenario, people only walk along a corridor. In the second, they remain seated in specific places. Describe these as different tasks even if considering the same model for both. For the corridor, seek a match with the route's shape; for seated occupancy, explicit information for that use. The category name alone does not answer both questions.

If documentation is detailed for only one scenario, retain the option as confirmed only for that part of the comparison. Do not fill the other part by analogy. This makes the shortlist more useful: instead of a general “suitable” assessment, each model has a clear basis and a specific unresolved condition. The next question to the specialist or manufacturer is then precisely framed.

Separate detection from control

A KNX interface is stated for Dual HF KNX 059477. This is information about its system connection, separate from the high-frequency detection principle. Two sensors may use a similar principle yet require different control systems.

Record the existing system's interface before making the selection. The STEINEL KNX and DALI presence detectors sections can help limit the search by system. Inclusion in the category itself, however, does not replace checking the selected reference and required components.

In the same example, the manufacturer lists illuminance thresholds and time settings separately. Do not confuse them with detection geometry. Record separately how the area is described and which control capabilities are available. This example provides no basis for setting one universally preferred setting for all rooms.

Short specification before the final choice

Prepare a five-part description: room type, desired zone, adjacent spaces and partitions, movement pattern and control interface. Add the exact reference and document supplying the characteristics for every candidate. Note all unconfirmed conditions separately.

This keeps comparison of the offers from STEINEL specific: which model is described for the required area shape, using which method and for which system. You obtain a verifiable selection list without turning general technology descriptions into a promise of unconditional detection in every real room.