HVACR116 – Trade Skills Mechanical Drawings

Objectives After completing this unit, you will be able to perform the following tasks: Identify and briefly describe the major pieces of HVAC equipment to be used in a building List the sizes of pipes and fittings shown on mechanical plans, and explain the major functions of each Describe the sizes and shapes of air-handling ducts shown on mechanical drawings

Heating, Ventilating, and Air Conditioning Plans Systems for larger buildings are designed by an engineer specialist Usually drawn on outline of building floor plan Shows location of HVAC and plumbing equipment Warm air heating ducts carry warm air to spaces and returns cool air to the source Allows for inexpensive air-conditioning

Unit Ventilators Unit ventilators mix room air and outside air to ventilate while warming Warmth is provided by hot water piped from boiler Figure 40–1. Unit ventilator schedule.

Figure 40-2. Operation of a unit ventilator.

Figure 40–3. Schedules of cabinet unit heaters, unit heaters, and fan cabinet unit heaters.

Heating Piping A solid line indicates supply pipes A dashed line indicates return pipes Pipe sizes are indicated by callouts Fittings are represented by symbols

Figure 40–4. Mechanical and plumbing symbols.

Figure 40–4. (continued)

Heating Piping (cont’d.) Figure 40–4. (continued)

Heating Piping (cont’d.) When pipes need to drop down from the ceiling to the ventilators, they are shown in isometric views Figure 40–5. This isometric drawing shows how the heating pipes drop down from the ceiling to the level of the ventilators.

Heating Piping (cont’d.) Figure 40–6. Noises are eliminated by allowing pipes to expand and contract.

Air-Handling Equipment Unit ventilators introduce fresh air Separate ventilation system removes stale air A louvered grille receives air and channels it into a duct Figure 40–7. Explanation of grille designations.

Air-Handling Equipment (cont’d.) Fire dampers close off ducts if they get hot in a fire Figure 40–8. Fire damper for ductwork.

DWV system is more complex for a large building Plumbing DWV system is more complex for a large building Figure 40–9. Riser diagrams for school fixtures.

Electrical Drawings

Objectives After completing this unit, you will be able to perform the following tasks: Explain the information found on a lighting plan List the equipment served by an individual branch circuit using electrical plans, riser drawings, and schedules Explain the information on a schematic diagram

Electrical Drawings Deal predominantly with circuits Basic methods of showing electrical circuits: Plan views Single-line diagrams Riser diagrams Schematic diagrams

Plan Views Shows exterior walls, interior partitions, windows, doors, stairs, cabinets, etc. Also location of electrical items and circuitry Power circuit electrical floor plan shows electrical outlets and devices Includes duplex outlets, specialty outlets, telephone, fire alarm, etc.

Figure 41–1. Circuiting symbols.

Plan Views (cont’d.) Lighting circuit electrical floor plan shows light fixtures, emergency lighting, security lighting, and special lighting control Figure 41–2. Reflected ceiling plan.

Plan Views (cont’d.) Electrical symbols simplify drafting and interpreting of drawings Not standardized Figure 41–4. Recommended electrical symbols.

Single-Line Diagrams Electrical service, or electrical distribution raceway, may need concrete encasing for protection (i.e., duct bank) Figure 41–5. Duct bank system.

Riser Diagrams Shows path of wiring or raceway from one level of a building to another Wiring rises from one floor to the next Does not give equipment location Power riser diagrams show typical building electrical service and related components

Figure 41–6. Typical riser diagram showing an overview of the building’s electrical service and related components.

Riser Diagrams (cont’d.) A special riser diagram is used for many systems: Fire alarm Security Telephone Clock Signals (e.g., bell)

Schematic Diagrams Symbols and lines show how parts are connected Do not have to show location Figure 41–9. Schematic diagram and wiring diagram for a three-phase, ac magnetic, nonreversing motor starter.

Schedules Used to systematically list equipment, loads, devices, and information Fixture schedule lists complete information about each fixture on lighting plan Mark Make Volts Watts Lamp type and quantity Notes or remarks

Schedules (cont’d.) Other schedules include: Panel schedules Kitchen equipment schedules Receptacle schedule Equipment schedule Connect load schedule

Specifications Items that establish intended design and required construction requirements Contractors and installers must review contract documents for conflicts and/or discrepancies between contract, specifications, and drawings Electrical specifications give quality of materials, installation, and testing requirements