1. HVACR116 – Trade Skills
Mechanical Drawings

2. 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

3. 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

4. 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.

5. Figure 40-2. Operation of a unit ventilator.

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

7. 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

8. Figure 40–4. Mechanical and plumbing symbols.

9. Figure 40–4. (continued)

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

11. 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.

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

13. 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.

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

15. 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.

16. Electrical Drawings

17. 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

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

19. 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.

20. Figure 41–1. Circuiting symbols.

21. 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.

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

23. 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.

24. 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

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

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

27. 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.

28. 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

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

30. 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