Sentence 9.32.3.8.(5)

Intent 1:

To limit the probability of the premature failure of supply fans, which could lead to excessive negative pressure.

This is to limit the probability of:

• the ingress of soil gases (such as methane and radon),
• the spillage of combustion products from fuel-burning appliances that are susceptible to spillage, or
• moisture ingress from the ground, which could lead to the generation of pollutants from biological growth or from materials that become unstable on wetting.

This is to limit the probability of negative effects on the air quality of indoor spaces, which could lead to harm to persons.

Intent 2:

To exempt supply fans from the requirement to be approved to handle untempered outdoor air, in situations where the outdoor makeup air is tempered before it reaches the supply fan.