Construction Drawings and Documentation

Construction drawings represent the primary communication medium between design intent and field installation. For HVAC systems, the drawing set must convey three-dimensional spatial relationships, performance requirements, and installation specifications with precision sufficient to support accurate construction and regulatory compliance.

Drawing Set Organization

Mechanical Drawing Sequence

Standard practice organizes mechanical drawings according to CSI MasterFormat divisions:

Drawing Type Sequence:

• General mechanical notes and symbols (M-000 series)
• HVAC plans (M-100 series)
• Plumbing plans (M-200 series)
• Fire protection plans (M-300 series)
• Mechanical details (M-400 series)
• Mechanical schedules (M-500 series)
• Control diagrams (M-600 series)
• Sections and riser diagrams (M-700 series)

Sheet Layout Standards

Each drawing sheet follows consistent organizational principles:

Title Block Components:

• Project identification and address
• Sheet title and number
• Drawing scale(s)
• North arrow orientation
• Revision history with dates
• Professional seal and signature
• Issue date and phase designation

Drawing Area Organization:

• Primary plan view occupies central position
• Enlarged details positioned peripherally
• Schedules placed in available space
• General notes located consistently across sheets
• Match lines coordinate with adjacent sheets

HVAC Plan Drawings

Plan View Content

Floor plans represent the horizontal projection of HVAC systems at specific cutting planes:

Ductwork Representation:

• Supply duct runs shown as single lines or double lines based on scale
• Return duct runs differentiated by line weight or pattern
• Exhaust duct runs identified by unique line type
• Duct sizes indicated at changes and regular intervals
• Fittings shown at direction changes
• Fire dampers, volume dampers, and access doors noted
• Flexible duct connections indicated

Equipment Placement:

• Air handling units with directional airflow arrows
• Rooftop units with curb dimensions
• Terminal units with serving zones identified
• Exhaust fans with discharge direction
• Equipment clearances for maintenance access
• Seismic restraint requirements noted

Piping Systems:

• Chilled water supply and return mains
• Heating hot water distribution
• Condensate drain routing
• Refrigerant piping for split systems
• Pipe sizes at all changes
• Isolation valves and balancing valves
• Pipe slope indicators for drainage
• Pipe support spacing requirements

Terminal Devices:

• Diffuser types and sizes
• Register and grille locations
• Linear slot diffuser runs
• Return air grille positions
• Thermostat locations
• Access panel requirements

Plan View Scales

Drawing scale selection balances detail resolution with sheet coverage:

Coordination Requirements

HVAC plans must coordinate with architectural, structural, electrical, plumbing, and fire protection disciplines:

Ceiling Height Verification:

• Finished ceiling elevations from architectural drawings
• Structural beam depths and locations
• Available plenum depth calculation
• Duct and pipe routing clearances
• Sprinkler head interference avoidance

Structural Coordination:

• Core penetrations through slabs and beams
• Roof curb locations and structural support
• Equipment pad locations and loading
• Hanger attachment points to structure
• Seismic bracing anchor points

Electrical Coordination:

• Power supply routing to equipment
• Disconnect switch locations
• Control wiring pathways
• Lighting fixture interference with ductwork
• Emergency power requirements

Section Drawings

Building Sections

Vertical sections cut through the building reveal vertical distribution systems and floor-to-floor relationships:

Section Content:

• Main supply and return duct risers
• Vertical pipe chases with pipe sizes
• Equipment room floor elevations
• Ceiling heights and plenum depths
• Structural members affecting routing
• Floor penetration details
• Vertical clearances to equipment

Critical Dimensions:

• Floor-to-floor heights
• Finished floor to underside of structure
• Bottom of duct to finished ceiling
• Equipment height and clearance requirements
• Roof penetration heights above roof surface

Mechanical Room Sections

Sections through mechanical rooms provide installation guidance for complex equipment arrangements:

Equipment Sections Show:

• Duct connections to air handling units
• Pipe connections with vertical offsets
• Clearance dimensions for maintenance
• Access aisle widths
• Door swing clearances
• Overhead clearance for component removal
• Foundation and curb details
• Vibration isolation spring deflection

Typical Section Details

Standardized sections document recurring installation conditions:

Common Section Types:

• Duct shaft vertical distribution
• Pipe chase with multiple systems
• Above-ceiling duct and pipe coordination
• Rooftop equipment curb and flashing
• Underfloor duct distribution
• Trenched piping in slab

Detail Drawings

Duct Details

Ductwork details clarify fabrication and installation requirements beyond what plans and sections communicate:

Connection Details:

• Duct-to-equipment transitions
• Branch takeoff configurations
• Turning vane installation in elbows
• Flexible duct connection methods
• Fire damper sleeve installation
• Duct access door locations and types
• Sound attenuator installation

Support Details:

• Trapeze hanger assemblies
• Strap hanger spacing and sizing
• Anti-sway bracing methods
• Riser support at floor penetrations
• Seismic restraint configurations
• Vibration isolation hanger selection

Sealing Details:

• Duct seam and joint sealing methods
• Penetration fire stopping
• Vapor barrier termination at equipment
• Outdoor air intake weather sealing

Piping Details

Piping details ensure proper installation of hydronic and refrigerant systems:

Pipe Connection Details:

• Pipe-to-equipment connections with isolation
• Expansion loop configurations
• Branch connection methods
• Valve installation with service space
• Strainer installation orientation
• Pressure gauge and thermometer wells
• Air vent and drain valve locations

Pipe Support Details:

• Clevis hanger with insulation protection
• Roller support for thermal expansion
• Riser clamp at floor penetrations
• Pipe anchor locations and types
• Seismic bracing spacing and configuration
• Trapeze support for multiple pipes

Insulation Details:

• Vapor barrier application and sealing
• Support protection saddles
• Penetration vapor seal
• Valve and fitting insulation coverage
• Outdoor insulation weatherproofing

Equipment Details

Equipment installation details document mounting, connection, and integration requirements:

Equipment Mounting:

• Vibration isolation spring or pad selection
• Equipment base and foundation details
• Seismic restraint attachment points
• Floor curb construction
• Roof curb flashing integration
• Housekeeping pad dimensions

Equipment Connections:

• Duct connection with flexible connector
• Pipe connection isolation methods
• Condensate drain trap configuration
• Electrical disconnect and wiring entry
• Control wiring termination
• Gas pipe connection with union and drip leg

Schedules

Equipment Schedules

Tabular schedules consolidate equipment performance data and specification requirements:

Air Handling Unit Schedule:

Exhaust Fan Schedule:

Boiler Schedule:

Diffuser and Grille Schedule

Air distribution terminal devices require comprehensive scheduling:

Diffuser Schedule Format:

Critical Schedule Information:

• Manufacturer model number or acceptable equal
• Airflow quantity from load calculations
• Throw distance and terminal velocity
• Sound performance rating
• Finish specification
• Damper type (opposed blade, single blade)
• Mounting method (lay-in, surface, concealed)

Control Device Schedule

Control components require detailed specification:

Control Valve Schedule:

| Mark | Size | Type | CV | Actuator | Power | Signal | Remarks | |——|——|——|—-|——— |——-|——–|———| | CV-1 | 3" | 2-way | 85 | Electric | 24V | 0-10V | Chilled water | | CV-2 | 2" | 3-way | 40 | Pneumatic | 20 psi | 3-15 psi | Hot water |

Damper Schedule:

Control Diagrams

Sequence Diagrams

Control sequence diagrams illustrate system operation under various conditions:

Diagram Components:

• Controlled devices (valves, dampers, fans)
• Sensors and measurement points
• Control logic decision points
• Setpoints and deadbands
• Interlocks and safety shutdowns
• Staging sequences for multiple units

Diagram Types:

• Psychrometric control sequence showing heating, cooling, economizing
• Boiler staging and rotation logic
• Chiller sequencing with tower coordination
• VAV box control with reheat
• Demand-controlled ventilation logic

Point-to-Point Wiring Diagrams

Wiring diagrams detail electrical connections between control components:

Wiring Diagram Content:

• Controller input and output terminal designations
• Wire gauge and conductor count
• Voltage levels for power and control circuits
• Shield and ground connections
• Junction box locations
• Conduit routing requirements

System Schematic Diagrams

Schematics represent system hydraulic or pneumatic relationships:

Hydronic System Schematics:

• Piping flow direction with arrows
• Pumps with flow and head
• Control valves with normally open/closed designation
• Coils with capacity ratings
• Isolation and balancing valve locations
• Expansion tank and air separator placement
• Temperature and pressure sensor locations

Pneumatic Control Schematics:

• Air compressor and receiver
• Main and branch air distribution
• Pressure reducing stations
• Thermostat and controller symbols
• Actuator spring ranges
• Tubing sizes and materials

Riser Diagrams

Vertical Distribution Diagrams

Riser diagrams illustrate vertical system distribution without floor plan complexity:

Duct Riser Diagrams:

• Main supply and return duct sizes
• Floor connections with branch sizes
• Fire dampers at floor penetrations
• Vertical support and seismic bracing locations
• Acoustic lining requirements
• Access door positions

Pipe Riser Diagrams:

• Main supply and return pipe sizes
• Floor connection pipe sizes
• Shutoff valves for floor isolation
• Balancing valve locations
• Pressure gauge connections
• Expansion compensation methods
• Insulation requirements

Multi-Story System Representation

For buildings with repetitive floors, riser diagrams efficiently communicate vertical distribution:

Diagram Features:

• Typical floor connection detail
• Variation floors shown individually
• Vertical dimension coordination
• Equipment room supply/return connections
• Roof equipment connections
• Basement or ground floor distribution

Drawing Standards and Conventions

Line Types and Weights

Standardized line representation ensures clear communication:

Symbol Libraries

Consistent graphical symbols represent HVAC components:

Equipment Symbols:

• Air handling unit: Rectangle with fan wheel symbol
• Exhaust fan: Circle with fan blade and directional arrow
• Boiler: Rectangle with wavy lines (fire symbol)
• Chiller: Rectangle with refrigeration cycle representation
• Pump: Circle with impeller blades
• Cooling tower: Rectangle with fill pattern

Device Symbols:

• Fire damper: FD in circle at duct
• Volume damper: VD with control line
• Diffuser: Square with diagonal lines
• Return grille: Square with horizontal lines
• Thermostat: T in circle
• Pressure gauge: PG in circle

Valve Symbols:

• Gate valve: Solid wedge
• Ball valve: Circle with diagonal line
• Globe valve: Circular with restriction
• Check valve: Arrow with barrier
• Butterfly valve: Line with disk
• Control valve: Valve symbol with actuator

Abbreviations

Standard abbreviations reduce drawing clutter while maintaining clarity:

Common HVAC Abbreviations:

• AHU: Air Handling Unit
• CFM: Cubic Feet per Minute
• CHW: Chilled Water
• CHWP: Chilled Water Pump
• DX: Direct Expansion
• EAT: Entering Air Temperature
• ERV: Energy Recovery Ventilator
• ESP: External Static Pressure
• GPM: Gallons per Minute
• HHW: Heating Hot Water
• HHWP: Heating Hot Water Pump
• HP: Horsepower
• MAU: Makeup Air Unit
• MBH: Thousand BTU per Hour
• OA: Outside Air
• RA: Return Air
• RTU: Rooftop Unit
• SA: Supply Air
• VAV: Variable Air Volume
• VFD: Variable Frequency Drive

Dimensioning Practices

Accurate dimensioning enables field layout and verification:

Dimension Requirements:

• Equipment centerlines to structural grid
• Duct and pipe centerlines to walls
• Clearance dimensions around equipment
• Elevation dimensions to finished floor datum
• Penetration locations through structural members
• Critical alignment dimensions for connections

Dimension Chain Management:

• Avoid cumulative tolerances
• Dimension to unchangeable references
• Provide overall dimensions for verification
• Note which dimensions take precedence

General Notes and Specifications

Drawing Notes

General notes apply to all work of a particular type:

Ductwork Notes:

1. All ductwork shall comply with SMACNA HVAC Duct Construction Standards - Metal and Flexible.
2. Duct construction class as indicated on schedules; Class 2 minimum unless noted otherwise.
3. Seal all duct joints and seams to achieve Seal Class A per SMACNA.
4. Install fire dampers at all rated wall and floor penetrations per code requirements.
5. Provide turning vanes in all rectangular elbows.
6. Insulate all supply ductwork in unconditioned spaces with 2" fiberglass duct wrap, R-6 minimum.
7. Acoustically line ductwork as shown to achieve specified NC levels.

Piping Notes:

1. Provide full-port ball valves at all equipment connections for isolation.
2. Install strainers upstream of all control valves and specialty equipment.
3. Insulate all chilled water and heating hot water piping with fiberglass pipe insulation.
4. Pitch condensate drain piping 1/4" per foot minimum toward drain connection.
5. Provide unions at all equipment connections for service access.
6. Install pressure gauges and thermometer wells at equipment connections.
7. Flush and chemically clean all hydronic piping systems before operation.

Installation Notes:

1. Verify all dimensions in field before fabrication.
2. Coordinate work with other trades; notify engineer of conflicts.
3. Obtain engineer’s written approval before deviating from drawings.
4. Provide vibration isolation for all rotating equipment per details.
5. Install seismic restraints per structural drawings and details.
6. Maintain minimum clearances for equipment access and maintenance.

Specification Cross-References

Drawings reference technical specifications for detailed requirements:

Specification Callouts:

• Material specifications: “Ductwork per Section 23 31 00”
• Installation requirements: “Equipment installation per Section 23 05 13”
• Testing procedures: “Air balancing per Section 23 05 93”
• Performance criteria: “Sound levels per Section 23 01 50”

Coordination Drawings

Composite Overlay Drawings

Coordination drawings combine multiple disciplines to resolve conflicts:

Overlay Content:

• Structural beams and columns
• HVAC ductwork and piping
• Plumbing waste and vent
• Fire protection sprinkler mains
• Electrical conduit and cable tray
• Architectural reflected ceiling plan

Conflict Resolution:

• Identify spatial interferences
• Establish priority for routing
• Determine elevation adjustments
• Coordinate penetration locations
• Verify maintenance access preservation

BIM Coordination Models

Building Information Modeling enables three-dimensional coordination:

BIM Coordination Process:

• Combine discipline-specific 3D models
• Execute automated clash detection
• Review clashes by priority and location
• Resolve conflicts through design adjustment
• Document resolutions in coordination reports
• Update construction documents to reflect coordination

Shop Drawing Requirements

Construction drawings establish requirements for contractor-prepared shop drawings:

Shop Drawing Submittal Requirements:

• Equipment shop drawings with certified performance data
• Duct and pipe fabrication drawings for complex assemblies
• Equipment layout drawings showing clearances and connections
• Control system points list and sequences
• Coordination drawings for congested areas

Review Criteria:

• Compliance with design intent and specifications
• Dimensional accuracy and coordination
• Performance data verification
• Accessibility for maintenance
• Code compliance confirmation

As-Built Documentation Requirements

Construction drawings form the basis for as-built records:

As-Built Marking Requirements:

• Red-line all field changes and modifications
• Document equipment substitutions and model numbers
• Record actual pipe and duct sizes if different from design
• Note control device locations and settings
• Identify concealed ductwork and piping routing
• Record penetration locations and firestopping details

Record Drawing Deliverables:

• Updated CAD files incorporating all as-built changes
• Equipment submittals with certified performance data
• Test and balance reports with final settings
• Control system programming and graphics
• Operations and maintenance manuals
• Warranty documentation

Comprehensive construction drawings serve as the contractual basis for HVAC system installation. The drawings must provide sufficient detail for accurate construction while maintaining clarity through organized presentation, standardized symbols, and proper annotation. Coordination between disciplines prevents conflicts and ensures systems integrate successfully within the building. Detailed schedules, sections, and details supplement plan views to communicate three-dimensional relationships and installation requirements. Proper documentation standards enable efficient construction, accurate as-built records, and long-term system maintenance.

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