23 34 00 HVAC FANS

01 General Owner Requirements and Design Intent

1. Design for High Energy-Efficiency Performance:  Professional shall design each fan application for optimal operating efficiency, and flexibility with the lowest life cycle cost.
1. Design Professional shall carefully evaluate and properly select the most effective fan type and wheel to best suit the needs of the application with emphasis on stable and quiet operation and minimizing
   operating and life cycle cost, rather than minimizing size and first cost.
   1. Typically the backward oriented wheel designs (airfoil, backward curved, and backward inclined) offer greater peak efficiency, greater strength and non-overloading power characteristics and should be used whenever available as an option in lieu of forward curved wheels for central fans and air handling equipment.
   2. Fan selections at the actual operating point(s) shall be within 10 percent of the peak total efficiency.
   3. In all cases, selections shall be made to avoid stall, surge and pulsating conditions throughout full range of operating range of fan system.
   4. Select for quiet operation.  The only valid basis for comparison are the actual sound power levels generated by the different types of fans when they are all producing the required volume airflow rate and total pressure. Sound power level data shall be obtained from the fan manufacturer for the specific fans being considered.  Low outlet velocity does not necessarily ensure quiet operation, so selections made on this basis alone are not appropriate. Also, noise comparisons of different types of fans, or fans offered by different manufacturers, made on the basis of rotational or tip speed are not valid.
2. The total allowable fan power limitation for each system shall be 10% less than the limits set by ASHRAE 90.1 or the current International Energy Conservation Code (whichever is more stringent), or as otherwise modified by most current edition of ASHRAE Standard 189.1.
3. Refer to 23 31 00 HVAC Ducts and Casings for duct design and air system design.
4. Minimize fan System Effects:  Avoid poor fan inlet and outlet conditions that reduce fan performance and increase energy waste.  Always consult manufacturer’s installation guidelines.
   1. Rules of thumb - AMCA.
      1. AMCA Publication 201 quantifies System Effect for several of the more common causes and offers recommendations for avoiding System Effect.
      2. On the fan’s inlet side, AMCA Publication 201 recommends that elbows near the fan’s inlet be located at least three duct diameters upstream of the fan, while acknowledging that elbows can cause System Effect when they are located up to five diameters upstream.
      3. On the fan’s outlet side, AMCA Publication 201 introduces the term “Effective Duct Length".
      4. Effective Duct Length is 2.5 duct diameters when duct velocities are 2500 fpm or less, with one duct diameter added for each additional 1000 fpm. A centrifugal fan needs 100% of an Effective Duct Length on its outlet to avoid System Effect, while vane-axial fan needs 50% Effective Duct Length.
5. Part Load Capacity Controls shall be effectively applied to fullest extent practical for optimal energy efficiency over entire system operating range.
2. Reliability and Redundancy: Professional shall determine the consequences of system failure and provide for adequate system redundancy for each application.
1. Confirm Owner requirements for redundancy are defined and met. 
2. Install fully redundant (N+1) stand-by fans for extremely critical applications (such as critical research laboratories and computer centers) and/or as otherwise defined specifically in the Owner’s Project Requirements.
3. For non-critical applications (such as general office spaces, general purpose classrooms, general commercial type spaces) full redundancy/complete standby is typically not required.
4. Consider parallel fan configurations where effective and practical.
5. Determine and specify applicable emergency power requirements. (Research, lab fume hood, process or other specific critical application).
3. Flexibility: Consider potential future expansion. Extent of expansion will be determined on a case-by-case basis. Consult with the University Project Leader and Engineering Services.
4. Space Planning:  Refer to 01 05 05 Space Planning
1. Make sure that minimum clearances are maintained, as required by manufacturer.
2. Allow at least three feet between all service sides of fans, and other large equipment and obstructions.
3. Mechanical room locations and placement must take into account how fans and replacement parts can be moved into and out of the building during installation and future major repair/replacement.
4. Plan for and clearly label any future equipment space needs on drawings.
5. Controls must not be placed in public areas.
5. Sound and Vibration Control:
1. Determine sound attenuation requirements.
1. Properly locate and specify to meet project needs.
2. Comply with requirements for vibration isolation devices specified in Division 23 Section  23 05 01 Mechanical General Requirements, .04 Sound and Vibration Control.
2. Minimize objectionable fan noise from intake or exhaust points to nearby buildings or sensitive neighboring areas.
3. Determine project and application specific vibration criteria requirements and specify appropriate factory and field vibration testing with allowable vibration limits for each application of fan, motor and base combination according to level of criticality. Review and edit the vibration testing portion of the fan specifications to ensure systems will operate without excessive vibration, but also not so stringent that it is difficult to meet without adding significant cost and time to the project.
6. Specialized exhaust systems - (Clothes Dryer, Kitchen Grease/Heat, Hazardous, Research Lab Fume Hood, Smoke Control, etc.):
1. General:
1. Apply variable air volume control wherever practical for optimal energy conservation – beyond code minimum prescriptive requirements.
2. Comply with Chapter 5 Exhaust Systems of International Mechanical Code for special requirements.
3. Select fan materials and construction most suited for the application.  Considerations in selecting materials include resistance to chemical attack and corrosion, reaction to condensation, flame and smoke ratings, ease of installation, ease of repair or replacement, and maintenance costs.  Appropriate materials shall be selected from standard references and by consulting with manufacturers.
4. For critical systems and where filters or coils are provided maintain ability to remove and service filters without shutting the unit down. 
2. Fans for Laboratory Ventilation systems:
1. Comply with requirements in OPP Standards 23 00 10 Systems Selection and Application, .12 Laboratory Ventilation Systems, including all referenced industry standards.
7. Documentation:
1. Provide mechanical identification per University Standards, using the Equipment Acronym List.
2. Schedules: Shall be complete with area served, location, total air quantity, static pressures, operating temperatures minimum fan efficiency (maximum brake horsepower), motor hp, voltage, (including starter/speed drive type), special materials of construction, coatings, accessories, motor shaft grounding protection for VFD applications. whether on normal/emergency standby power (where applicable), any maximum dimensions and weights, sound power level data, method of control, and if fans are interlocked, indicate with which unit(s) the fan is interlocked. 
3. For lab fume hood high plume exhaust fan systems, Engineer must provide all pertinent selection criteria including: minimum plume heights; laboratory fume exhaust air and total flow design rates; quantity, size and location of bypass dampers; special corrosion-resistant materials and finishes; spark-resistance class, and any other application-specific options and accessories on equipment schedules.
4. The configuration of all components of fans, including fan/motor arrangement, rotation, and required dimensions for all internal access sections and external access clearances, shall be clearly defined in sufficient detail in plan and elevation views on the design documents.
5. Design Professional to submit Energy Compliance Document (sealed) after Design Development (DD) and prior to Construction Documents (CD).  

.02 Guide Specifications:

1. Design Professional shall carefully review and edit the guideline specifications below, adapting them as needed to achieve application-specific, fully developed specifications for each project.
2. These shall be edited using the process described in the instructions contained at the beginning of the document. Proposed modifications shall be reviewed with OPP staff.

3. Finalized version shall be included in the project contract documents. Use of other specifications is not acceptable.

   Document	Version Date	Description
   233416 CENTRIFUGAL HVAC FANS GUIDE SPECIFICATION	September 7, 2018	OPP minimum specification requirements for Centrifugal HVAC Fans