The Fresh Air Anemometer is an air-flow measurement device installed stationary into the building management system. It measures the airflow continuously over time. The measurement results are provided periodically with a period of 1–2 seconds. The following data is provided:
- Average airflow [L/s] of last second (period).
- Average airflow [L/s] of last running minute. The value is renewed once in a second.
- Average airflow [L/s] of the last running hour. The value is renewed once in a minute.
- Average airflow [L/s] profile in the last 24 running hours. The profile is renewed once in a minute.
| Attribute | Value |
| For duct diameter: | 100 mm |
| Calibrated range: | 5 .. 15 L/s |
| Reading precision: | 15% from reading |
| Calibrated temperature range: | -25 .. 60 oC |
| Calibrated air pressure range: | 900 .. 1100 hPa |
| Sampling interval: | 1 .. 2 s |
| Measurable range: | 2 .. 40 L/s |
| Power supply: | DC 8 .. 24 V |
| Current consumption @ 24V: | 5 .. 6 mA |
| Resistance @ 5 .. 15 L/s: | 2.6 L/(s√Pa) |
The airflow resistance is measured together with air intake.
The anemometer communicates with the building management system using the industrial standard Modbus RTU communication protocol. The RS485 interface survives up to 48V potential difference relative to a ground signal. The anemometer is capable of automatically adjust to swapped data D1 and D0 signals.
The Fresh Air Anemometer is a crucial part of the system that:
- Makes sure that the room is ventilated according to the required standards.
- Monitors for the need for duct cleaning.
- Together with VAV valves, it balances the ventilation system automatically.
- Compensates for the weather wind effects for the balance of the ventilation system.
- Minimizes energy losses through ventilation by avoiding over-ventilation.
- Distributes heating expenses based on the ventilation.
