HOW NOISY IS THE FAN?
Some of our clients deal with noise attenuation as part of their profession. These folks are inclined to look for technical data on the noise they can expect from their fan, but most manufacturers don’t provide it. Fan noise varies with the installation conditions. The same fan might sound very different depending on how permeable the underlying soils are and how much air it is moving. Consider a vacuum cleaner - by blocking the intake, the vacuum emits a much different sound.
In most circumstances, where the right fan is selected as part of the mitigation system design, the noise will be less than the hot water tank or furnace. There are exceptions. Some situations will require higher wattage fans that will be louder. Selecting the right fan means no more fan noise than necessary.