Verify proper airflow and control operations through pre-design baseline testing. Pre-design smoke or peppermint testing may be required if after review of existing drawings and EOR detailed survey has been completed and distribution/spaces served cannot be determined. Replace if non-functional. Rebalance system once replaced or repaired. Utilize direct drive units with ECM motors plus speed controller (fine tuning during balancing) when available in lieu of belts. Review with CPS before utilizing VFDs.
Fume hood exhaust fans shall be one per hood and utilize chemical/corrosion protected centrifugal utility set fans with vertical extension such that unit discharge is 10’ above roof surface. There are several fans on the market that offer the extension as an accessory and do not require guy wire supports. Locate on the highest roof when possible. Equipment sound / site enclosures shall not extend above fume hood fan discharge elevation. Where possible the point of discharge shall be 25’ horizontal from all building openings (windows, doors, intakes, etc.)
Refer to Volume 3, Section 6.3.5.7 for fan requirements and design considerations.