Acceptable noise levels from the home exhaust fan
If you are in the process of choosing and researching a home exhaust fan, you know that there are many technical aspects to consider: the size of the room, the number of air changes per hour, the extraction rate, part L of the Building Regulations, zoning the bathroom. system, duct length and resulting air pressure, IP rating, energy usage … the list seems endless!
The decision to retrofit an exhaust fan is generally driven by the need to expel steam from a bathroom or kitchen odors and is made by the property owner. When installing a fan in new construction, a real estate company or electrical contractor will install fans to meet Part L of the building regulations. In both cases, the most important factor is the air extraction rate – how much air is removed during a given period. This is expressed in cubic meters per hour (m3 / h) or liters per second (L / s).
However, an important consideration that is often overlooked by the homeowner and understandably the outside contractor is the noise the fan generates when it is operating.
Most manufacturers set the noise level of their fans in decibels dB (A) within the technical specification. This information is now easily found on the websites of manufacturers, retailers, and wholesalers. Those fans that don’t clearly display dB (A) probably have something to hide and should be avoided.
So what is an acceptable noise level? To some extent, this is subjective; what is good for some may be annoying for others. However, the installation and type of fan have a great influence on this answer. Most kitchen fans are six inches, meaning they use a six-inch impeller. (Unlike most bathroom fans that use a four-inch impeller.) Consequently, a larger motor is required to drive it. There is simply no way around the fact that a larger motor will result in a high decibel level. In fact, even the quietest six-inch fans are louder when running than the loudest four-inch fans. However, the kitchen is a room that can accommodate higher decibel levels. Why? … well, think about how the fan is being used: The fan is almost certainly being used to extract kitchen odors. In this situation, the user and other inhabitants of the property will be much less aware of the noise of the fan, being obscured by the sounds of food preparation.
However, four-inch fans are used at completely different times. Nightly visits to the bathroom or toilet, for example, when the house is completely silent, are much more audible. The opening and closing of a door, the creaking of a floorboard can be heard in different parts of the house. In this situation, the fan noise is much more prominent. Until recently, this simply couldn’t be helped – the engines were inherently noisy. However, almost all manufacturers now make a specifically silent fan or a range of silent fans. While most normal four-inch models operate at around 30 – 40 dB (A), these silent or silent models operate at around 24 d (B) A. As long as the fan is installed correctly and is not mounted on a wooden beam, they will remain silent, even in the middle of the night.
More information on silent extractors is available at Extractor Fan World.
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