A classic reflex in air handling unit specifications: a differential pressure switch to detect clogged filters.
The problem? With variable airflow, that fixed threshold stops meaning anything. A filter’s pressure drop depends on two things: how clogged it is and the airflow rate. The result:
- at low airflow, a saturated filter may never trigger the alarm;
- at high airflow, a clean filter may trigger it by mistake.
A pressure switch calibrated to nominal airflow becomes either blind or oversensitive as soon as the airflow changes.
Our recommendation at Workswell: a pressure sensor. It measures ΔP continuously, in proportion to actual airflow. Three concrete benefits:
- reliable detection, regardless of the operating point;
- trend tracking over time;
- predictive maintenance instead of an all-or-nothing alarm.
Constant airflow: the pressure switch is enough. Variable airflow: the pressure sensor is no longer optional.
Writing a specification for an air handling unit? Let’s talk.