1. Heating, Ventilating, and Air-Conditioning (HVAC)
Chapter 21
Heating, Ventilating, and Air-Conditioning (HVAC)

2. 3 Methods of Heat Transfer?
Overview
Code Requirements
Heating Systems
Zone Control
HVAC Drawings
3 Methods of Heat Transfer?
Hint (C.C.R)

3. Introduction Heating, ventilating, and air-conditioning (HVAC)
Heating and air-conditioning equipment, and systems found in a building
Also referred to as the mechanical system
Regulates temperature
International Residential Code (IRC)
Requires a heating unit in any residence built in an area where winter design temperature is below 60°

4. Thermal Calculations for Heating/Cooling
Necessary to establish the correct:
Furnace
Ductwork
Supply
Return register specifications
Historical primary use
Calculate design heat load of houses to estimate gas and oil heating systems size

5. Thermal Calculations for Heating/Cooling (cont’d.)
HVAC terminology:
Btu
Indoor Air Quality (IAQ)
Duct loss
Cubic Feet/ Min. (CFM)
Heat transfer multiplier
Indoor temperature
Air Changes per Hour (ACH)
Indoor wet bulb
Infiltration
Internal heat gain
Latent load
Mechanical ventilation

6. Thermal Calculations for Heating/Cooling (cont’d.)
HVAC terminology (cont’d.):
Outdoor temperature
Outdoor wet bulb
R-factor
Sensible load calculations
Temperature difference
U-factor

7. Thermostats
Automatic mechanism for controlling heating or cooling by a central or zonal system
Location is important

8. Exhaust Systems: Code Requirements
Exhausts are part of the HVAC system
Exhaust systems are required to remove odors, steam, moisture, and pollutants
Refer to the text for basic general code requirements

9. HVAC Code Requirements
National Energy Conservation Code regulates the design and construction of:
Exterior envelope and selection of HVAC
Service water heating
Electrical distribution
Illuminating systems and required equipment
Refer to the text for general code requirements

10. Code Requirements
IECC is updated every three years and is designed to provide an energy efficient environment for humans
Equipment in a garage must be protected from automobile impact (slab on grade construction would have a 18” platform)
Programmable Thermostat
Exterior (Building) envelope is space that is heated and cooled
Conditioned (finished square footage)
Unconditioned (basement unfinished)
Must be separated by a door

11. Code Requirements
A door or access large enough to remove largest piece of equipment
Unobstructed working space not less than 30” wide and high should be provided next to the control side of the equipment (Furnace, WH)
An GFCI electrical outlet and lighting fixture should be provided near the equipment and have a switch at the doorway or access (In attic)
Equipment located on the ground should be supported on a concrete slab and be at least 3” above the ground. (AC units)
Fuel burning warm-air furnaces must be supplied with combustion air
All exterior ducting (Avoid at all costs) should be weatherproof and insulated
In basements all supply lines should be insulated with R-4.2 insulation unless wall drapes are used to consider it conditioned space

12. Minimum Dimensions Furnace 24 x 30 Water Heater 18-24” Diameter
Electrical Panel 30” open space
Pex Piping

13. Duct Systems
Cold Air Return
Supply

14. Central Forced-Air Systems

15. Forced Air Systems
A fan forces air into ducts that connect to air supply registers
Air is heated during the heating cycle and the combustion is vented out flue
Cooled air is passed over a cooling coil which is cooled with a refrigerant (Puron)

16. Forced-Air Heating Plans
Complete forced-air heating plans show:
Size, location, and number of British thermal units (Btu) dispersed from warm-air supplies
Location and size of cold-air return
Location, type, and output of furnace
Providing duct space (i.e., chase)
When ducted heating and cooling systems are used, duct location becomes important

17. Central Air Systems Rules to Design
Place Central Air Condenser unit at shortest straight line to exterior side or rear of home for coil (efficiency)
Place Ducting trunks cold air returns and supply lines to one side of bearing wall (Stairs)
Add Combustion Air Intake direct line same direction floor joist are running

18. Zone Control Systems One heater and one thermostat per room Types:
No duct work
Only heaters in occupied rooms need to be turned on
Types:
Baseboard
Fan heaters
Split systems

19. Alternate Method using Zone Controls
Individual rooms are heated and cooled as needed

20. Hot Water System
Water is circulated through a radiator after being heated in an oil- or gas-fired boiler
One-pipe system has heated water pass through radiators and returns in the same pipe to the boiler
Radiant Flooring is growing in popularity

21. Hot Water Systems Water is heated in an oil- or gas-fired boiler
Then circulated through pipes to radiators or convectors

22. Radiant Heat Radiant heating and cooling systems
Control surface temperatures
Minimize excessive air motion
Annual operating cost savings of 20% to 50%
Lower thermostat settings
Superior, cost-effective design

23. Heat Pump/ Geothermal / Passive Solar Systems
Heat is extracted from outside air and pumped through a compressor into the structure
Heat pump systems are 30 to 50 percent more efficient then forced air systems
Air is cleaner and fresher with a heat pump system

24. Heat Pump Systems Forced-air central heating and cooling system
Compressor and circulating refrigerant system

25. Exhaust System Code Requirements
Vented hoods must have back draft damper
Direct vent to exterior suggested for gas or exhaust fan in kitchen
If gas dryer or other fuel burning appliance (Fan is good idea)
Clothes dryer vents independent from all other systems.
No screws in vent
Back draft damper
4” duct no longer than 25’
Total length reduced 2.5’ for each 45 bend and 5’ for each 90 bend

26. Heat Recovery and Ventilation
Uses a counter flow heat exchanger between inbound and outbound airflow
Air pollutants
Principle reason for installation
Air-to-air heat exchangers
Pulls polluted, stale, warm air from the space and transfers heat in that air to fresh, cold air being pulled into the space

28. Gas lines
Meter
Pressurized Gas
2lb
4 oz

29. HVAC Drawings Drawings for the HVAC system show:
Size and location of all equipment, ductwork, and components
Use accurate symbols, specifications, notes, and schedules
Form the basis of contract requirements for construction

32. Residential HVAC Drawings
Show Thermostat location
Heat Register Locations
4 x 10 floor or 2 x 10 under cabinet
Cold air return is needed for every 5 heat registers
14 x 8 single or 30 x 8 double
Size of room and use determines number of registers needed ~ 150 square feet = Single

33. Residential HVAC Drawings
Show Supply and Return Main Trunk Lines
Dryer Vent Location
Combustion Air Location
Residential HVAC Drawings