Airflow performance of a ventilating fan is subject to the factors that cause pressure loss. These factors could be expressed as below:

a) “Outside wind pressure” is especially important in the case of a high rise building subjected to strong wind.

b) “Airtightness of the room”, even a powerful fan is unable to ensure satisfactory performance if the room is airtight without air intake.

c) “Resistance of ducts”, the length and bend of duct should be minimized, and the resistances of inlet/outlet porys, grease filter, damper and other parts of duct should be taken into account.

d) “Resistance due to confluence” causes pressure loss by air confluence in the same duct.

In order to satisfy the required volume of ventilation, it is necessary to select the type of fan and the number of units, considering the pressure loss due to above factors.

Even if a ventilation fan is installed, its exhausting function would not work unless a proper air supply is secured.

Fresh air intake failure causes increases of carbon monoxide from combustion of fuel gas. As for the kitchen of a house being high in airtightness, a proper air intake plan for efficient and effective ventilation is important. It is known that when fuel gas burns, 5 times or even more than 10 times the amount of gas of air is consumed, depending on the kind of fuel gas. Hence, lack of proper air intake plan is bound to cause incomplete combustion or even oxygen shortage in your kitchen. Thus, it is essential to ensure enough supply of fresh air into the room during ventilation