1. Chapter 14 Heating, Ventilation & Air conditioning (hvac)
Construction Estimating
Prof R. V. Locurcio

2. Outline
HVAC Systems
Residential HVAC Systems
Commercial HVAC Systems

3. Definition
HVAC systems consist of equipment, ductwork, and piping used to heat and ventilate buildings and to condition (cool and dry) the air.
Equipment can be: a furnace, an air-conditioning coil, a compressor, a plenum, a boiler, a tank, a pump, manifolds, outlets, and valves, etc…

4. HVAC Systems
Two types considered
Residential

5. Residential HVAC Systems Two Types
Central heating and air-conditioning
Hot air systems
Hot water systems
Steam
Radiant heating used only to heat spaces

6. Central Heating and AC The most common residential HVAC systems
Functions to cool and heat spaces
System consists of:
A furnace supplying heated air through ductwork
A main trunk line of rectangular duct
Supply lines running from the trunk line to the registers or vents
A return air duct returning the air from the rooms to the furnace
Metal duct using air between joists and studs.
See Fig 14.1 to Fig. 14.4

7. Figures 14.1 to Fig 14.4

8. Example 14-1
Determine the HVAC components needed for the residence in figures 14-1 and 14-2.
The furnace includes an air-conditioner.
A 2”X2” register is required at each base cabinet.
A 6”x 18” grille is needed at each return air.
Distance top of furnace to the roof is 20 feet.
The vent pipe is 4 inches in diameter.

9. Solution-1
Equipment: a furnace, a coil, a compressor, and a plenum (enclosed space to facilitate air circulation)
For the supply trunk: 16 feet of 8”x 12” rectangular duct, two 8”x 12” to 8”x 8” transitions, 17 feet of 8” x 8”, and two 8” x 8” end caps are needed.
For the individual supply lines 6-inch 90-degree elbow are needed

10. View of HVAC System

11. Plan View of HVAC System

12. Solution-2
6-inch-diameter duct needed (17 ft + 17 ft + 19 ft + 19 ft + 2ft + 4 ft + 3 ft + 3 ft + 6 ft) = 90 feet
For base cabinets: three-6inch 90-degree elbow
Three 2” x 12” registers, six 4” x 12” boots, and six-4” x 12” registers
For the return air:
Two-6” x 18” grilles

13. Solution-3 Sheet metal: 15 feet of 18-inch-wide (1+4+1+1+7+1) ft
Two ea. 8” x 12” end caps
12 feet of 8” x 12” duct,
and 8 feet of 12” x 18” duct
from the trunk line to the
bottom of the furnace.

14. Solution-4
For the vents: 2 feet above the roof and 4 feet of pipe are needed; Two 4-inch 90-degree single-wall elbows, 4 feet of 4-inch-diameter single wall pipe, 22 feet of 4-inch-diameter double wall pipe, one 4-inch roof flashing, and one 4-inch termination cap.
One line set to connect the condenser to the coil,
one thermostat,
and one roll of
wiring are needed.

15. Radiant Heating Another type of residential heating
Uses hot water to warm the floor, which in turn warms the living space.
It consists of supply manifold, pump, boiler, return manifold, air ejector, expansion tank, and valves.
It cannot be used for cooling purposes
Figure 14-6 shows details about radiant heating

16. Equipment for Radiant Heating

17. Figure 14-7 Pipe Spacing

18. HVAC Systems
Two types considered
Commercial

19. Commercial HVAC Systems
Small commercial buildings often use HVAC systems similar to that of the residential system, using more
units as the building gets larger.
Larger single-story buildings often use a roof-top units
(package units) that heat and cool the air and then distribute it through the building using ductwork.
As building gets taller a heat exchanger is used. The heating and cooling is accomplished by heating or cooling water at a central point.
Commercial systems may also use chillers, boilers, dampers, fans, and variable-air-volume (VAV) boxes.

20. Commercial systems

21. Example 14-4
Determine the HVAC components needed for the commercial HVAC system shown in Figure 14-8.
Two feet of 6-inch-diameter flexible duct is used to connect the diffuser to the ductwork.
The plenum is used for return air. The existing supply and return lines are made of copper.

22. Figure 14-8

23. Figure 14-10

24. Figure 14.9

25. RESIDENTIAL HVAC

30. HVAC Equipment

31. Basic System

32. Upflow Furnace

33. Attic unit

34. Ductwork-1

35. Ductwork-2

36. Ductwork-3

37. Joining Flex Duct

38. Ductwork-4

39. Ductwork-5

40. AC Coils

41. Floor Plenum

42. Questions