Here at ATSPACE, we cover all aspects of ventilation testing. All our engineers are fully qualified and have years of experience testing all types of ventilation systems. But how do we test the flow of air that passes through your extractor fans and ventilation systems? I’m glad you asked, as we will detail how we can tell that your fans are up to scratch! 

The basics  

First, you will need a flowmeter or anemometer. Below are a few examples of these.  

The purpose of these instruments is to calculate the amount of airflow that passes from the internal surface of the fan to the external grill. Each fan location (which is commonly found in wet rooms, i.e. kitchen, utility, bathrooms, sanitary accommodation) must reach a certain benchmark, which is determined by Part F of the Building Regulations. See below the table of targets that each system must achieve. 

Taking the measurement 

 Actually, measuring the required ventilation rates is the easy part. The above instrument is simply placed over the fan, and the display will give a real-time output in litres per second (l/s) that the fan extracts. Once the figure displayed stabilises, the result is then recorded and a pass or fail is issued.  

This is complicated slightly when moving to a system 3 & 4 system. The reason is that these systems require ‘balancing’.’ This means each fan must be adjusted to allow the correct amount of flow to pass through them. In addition, these systems have interconnected fans, which means when one fan is adjusted, the flow for the others changes accordingly.  

Also, these systems require prior calculations to determine the flow required from the system. The table above shows the following factors are used; 

• •  Overall floor area

• •  Number of bedrooms

• •  Type of System

• •  Number of wet rooms

Once the above steps are complete, the engineer can then balance the system. They do this by adjusting the flow output and speed settings of the system to the required level, then using the flowmeter, adjusting individual vents to reach the required targets.