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PRELIMINARY DESIGN CONSIDERATIONS

The following is an overall review of issues to considerwhen designing your next custom air handling unit.

1.0 PHYSICAL DATA

1.1 ENVIRONMENTAL CONSIDERATIONS

1.1.1 Specify if the unit is an indoor or outdoor unit

1.1.3 If it is an indoor unit, specify if it is a conditioned mechanical space or seasonal. Determinehow it will be conditioned.

1.1.4 Consider the types of spaces or equipment adjacent to unit or mechanical room:

a. offices, theater, patient rooms, etc.b. pumps, chillers, VFDs, etc.

1.1.5 Determine any design constraints:a. opening locations - ends, roof, baseb. clearance around, over or under unitc. coil pull spaced. columns or other obstructions in or near unit

1.1.6 Determine unit support and its type and size

1.1.7 Check if there are any toxic, corrosive, or explosive substances in the airstream

1.1.8 Verify any seismic considerations

1.2 PHYSICAL -- Size & Weight1.2.1 Quantify any size or weight limitations due to:

a. space available for unitb. rigging constraints: opening or available access; helicopter weight limitsc. maximum allowable shipping sections, etc.

1.2.2 If outdoor, determine if a service corridor required and the minimum width of the corridor

1.3 CONSTRUCTION

1.3.1 Panel type -- mineral wool, fiberglass, foama. Determine if thermal break is requiredb. Assess if acoustical panels are required

1.3.2 Special construction considerations which should be made:a. Architectural considerations necessary to match the buildingb. Either stainless steel skins or coated skinsc. Specify if there will be special coatings on equipmentd. Highlight any special materials of construction on equipment (copper fin coils, etc.)e. Designate any special cleanliness considerations

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2.0 OPERATIONAL DATA

In order to provide optimum unit design it is important to understand how the air handling systemsis required to function. A flow diagram is recommended showing volumes, temperatures,pressures and humidities (for each season) to determine if unit design is reasonable. Is thesystem type the most economical for the required application?

2.1 UNIT TYPE

2.1.1 Constant or variable volume. If variable volume, determine VIVs or VFDs

2.1.2 Designate draw through or blow through configuration

2.1.3 Quantify duct velocity. Low / medium / high pressure duct system

2.1.4 100% OA or mixed air (economizer)a. If mixed air, standard or controlled mixingb. If economizer, return fan included with the unit

2.1.5 Choose chilled water or Dx cooling

2.1.6 Designate steam or hot water heating. Glycol (type and %)

2.1.7 Humidification select steam injection, spray system or evaporative media

2.1.8 Filtration -- pre & final filters, HEPAs, carbon filters

2.1.9 Heat reclaim specify heat wheel, heat pipes or run-around coil system

2.1.10 Specify if smoke dampers are required within the unit

2.1.11 Special design considerations:a. Determine if there are airborne or transmitted sound limitations. Quantify if the sound

requirements for this design and application are realistic. Assess if special construction isrequired to meet specified acoustical criteria levels.

b. Evaluate any vibration limitations

c. Determine if there is low temperature / low humidity

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2.2 DESIGN PARAMETERS

2.2.1 Design Volumesa. Supply CFMb. Return CFMc. Minimum OA CFMd. Exhaust CFM

2.2.2 External Static Pressuresa. Supplyb. Return

2.2.3 Design Temperatures & Conditionsa. OA db/wbb. RA db/wb (space condition)c. SA db/wb

2.2.4 Coolinga. Chilled water: Glycol - Ethylene or Propylene, %. Dx.

b. Entering fluid temperature. Dx suction temperature.c. GPM. Fluid temperature rised. Determine maximum fluid pressure loss

2.2.5 Heatinga. Hot water: Glycol - ethylene or propylene, %. Steam.b. Specify entering fluid temperature; Steam pressurec. GPM. Fluid temperature rise; steam flow rate, #/hr.d. Determine maximum fluid pressure loss

2.2.6 Humidificationa. Steam pressureb. Steam flow rate, #/hr.

2.2.7 Filtration

a. Pre-filter % efficiencyb. Final filter % efficiencyc. HEPA filter % efficiency

2.2.8 Sound power or sound pressure levelsa. inlet openingsb. discharge openingsc. outside casing at fan sections

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3.0 SCOPE DATA

3.1 GENERAL

3.1.1 Determine shipment or delivery; ship date

3.1.2 Warranty considerations: consider extended warranties

3.2 UNIT

3.2.1 Factory built or field built

3.2.2 Specify materials of construction

3.2.3 Determine necessary painting or special coatings

3.2.4 Special requirementsa. Cleaningb. Freight Prep -- wrapping

3.3 SPECIALTIES

3.3.1 Electrical:a. Lights (choose incandescent or fluorescent); convenience outletsb. Power Wiring--disconnects, starters, VFDs, etc.c. Conduit type--EMT, GRC, ARC

3.3.2 Piping:a. Designate chilled water, hot water or steamb. Insulation factory installed or field installed

3.3.3 Unit Controlsa. Damper actuators pneumatic / electric. Specify if provided and installed by unit

manufacturer. Installed only or provided by othersb. Control devices to consider temperature sensors, pressure sensors, smoke

detectors, etc. Determine if devices are to be provided and installed by unitmanufacturer or if they are to be installed only and provided by others.c. Unit controller: Designate if provided and installed by unit manufacturer or if it is to be

installed only and provided by others

3.4 TESTING

3.4.1 Leakage: % volume and test pressure

3.4.2 Flow and power consumption

3.4.3 Vibration: criteria; full spectrum

3.4.4 Acoustical: airborne or transmitted; criteria

3.5 FIELD

3.5.1 Specify field labor or supervision and either joining or erecting

3.5.2 Determine rigging supervision

3.5.3 Designate start-up labor or supervision and any necessary customer training