1. Air Handler Terminology
HVACR416 - Design
Air Handler Terminology

2. Basic System Components
Condenser
Condenser Coils
Compressor
Condenser Fan

3. Basic System Components
Condenser Coil
Can be shaped:
Horseshoe
Round
Flat / Straight
Can be folded over in more than one layer
The coil is a fin and tube design
Aluminum fins / copper tube
Aluminum fins / aluminum tubes

4. Basic System Components
Condenser Fan
A propeller type fan blade that pulls air through the condenser coil.
Air is NEVER pushed through the coil. If you ever see that check rotation of the fan.

5. Basic System Components
Compressor
Heart of the refrigeration cycle.
Gives off quite a bit of heat and is sometimes the noisiest component of the cycle.

6. Basic System Components
Air Handler
Blower section of the system
Used for circulating the conditioned air
Always present in A/C and heat pumps
Consists of:
Evaporator Coil
Metering Device
Blower

7. Basic System Components
Evaporator Coil
Inside Air Handler
Can be shaped:
“A” Shaped Coil
Flat Coil
Slant Coil
“H” Coil
“W” Coil

8. Basic System Components
Metering Device
Capillary Tube
Fixed Orifice
TXV (Thermostatic Expansion Vavle)

9. Basic System Components
Blower
Normally a squirrel cage type blower wheel
Direct Drive
Belt Drive
Usually a PSC, ECM, or Shaded Pole motor

10. Basic System Electrical
Air Handler
Indoor Fan Contactor
24 volt relay controls line voltage blower motor
Terminal Strip
Junction point for all of the wiring
Good practice is to use crimp connectors and forks for all connections to terminal strip.

11. Basic System Electrical
Air Handler
Integrated Control Board
The brains of the system
Monitors the operation of the indoor fan motor
Has timers and relays built into the control to start and stop the motor.
Controls the speed of an ECM motor.

12. Basic System Electrical
Air Handler
Low voltage transformer
Takes line voltage and steps it down to a lower voltage (24VAC)
Low voltage is called the “Control Voltage”
Line voltage is usually 240/208 or 120 Volts

13. Basic System Electrical
Condenser
Uses a relay coil to energize a compressor and fan.
Control voltage usually 24 volts
Sometimes has a delay timer
Sometimes uses a start capacitor
Always has a run capacitor
Uses a high pressure switch in case of unsafe refrigerant pressures.

14. Basic System Electrical
Condenser
Includes a low pressure switch in case of refrigerant loss.
Has a fan motor - usually a PSC type.

15. Basic System Electrical
Low Pressure Switch
Low pressure switch will open in a drop of pressure.
Can be caused by:
Dirty Evaporator Coil
Restricted evaporator air flow
Faulty evaporator fan motor
Low ambient temperatures

16. Basic System Electrical
High Pressure Switch
Opens on a rise in pressure
Usually around 300psi on R22 systems
Usually around psi on R410A
Caused by:
Dirty condenser coil
Restricted condenser air flow
Faulty condenser fan
Extremely high ambient temperatures

17. Basic System Mechanical
Air Handler
Evaporator has connections for the installation of copper tubing, or line sets.
Liquid line
Liquid refrigerants travel through this line
Typical sizes are 1/4”, 5/16”, 3/8” and 1/2”
Suction line
The suction line is the larger diameter tubing
Should always be fully insulated
Vapor refrigerant travels in this line
Typical sizes are 5/8”, 3/4”, 7/8” and 11/8”

18. Basic System Mechanical
Air Handler
Has condensate drain connections
Typically a 3/4” female PVC connection
If no drain is present:
A condensate removal pump must be installed to pump to a drain (sink, washer, etc)
Many installations will allow the tubing to drain outdoors (watch for freezing).
Attic installs allow pvc to drain into the gutter system or down the side of the house.

19. Basic System Mechanical
Condenser
Connection for the other end of the line sets.
Liquid line should always have a filter drier on it.
Filter is directional, liquid runs away from the condenser.
Heat pumps must have bi-directional filter drier.

20. Basic System Mechanical
Condenser
Usually installed outdoors
Must be installed level
Must be free of surrounding shrubs and any item that will restrict air flow.

21. Four basic common A/C systems
System Types
Four basic common A/C systems
Split System
Packaged System
Ductless Systems
Window Units

22. Split Systems
The evaporator and the condenser are separate pieces of equipment.
The evaporator section
Installed in attic, basement or closet
May be a part of the air handler
May be installed on a furnace
Has its own electrical power disconnect
Has its own circuit breaker

23. Air Handler Section Split Systems Contains the blower
Used for circulating conditioned air
Air conditioning and heat pumps use the air handler.

24. Air Handler Split Systems Consist of:
Evaporator Coil is a fin and tube design.
Metering device
Blower

25. Condenser Section Split System Consists of: Fan motor Condenser coil
Outside on a level pad
Own power source
Has its own circuit breaker
Must have a disconnect within arms reach of the unit
Consists of:
Fan motor
Condenser coil
Compressor
Controls

26. Packaged Unit Located outdoors
Usually commercial but sometimes seen in residential for mobile homes.
Mostly over 5 ton capacity in commercial.
All major components are located inside one unit.

27. Package Unit Major components Evaporator Condenser Compressor
Condenser Fans
Evaporator Fan (indoor blower)
Must have own circuit breaker
Must have disconnect within arms reach of unit

28. Package Unit Must have 120V outlet (GFCI) within arms length of unit.
Units are single or multi-stage.
Multistage allows for additional heating and cooling load control.
Stage 1 is for light duty conditions
Stage 2 is for more than a 2 degree difference between room temp and thermostat set point.

29. Package Units
Package units are mounted on a concrete slab or on a roof.
If on roof there is a roof curb and a plenum under it.
If mounted on slab the supply and return air ducts are on the side of the unit.
All ductwork must be insulated.

30. Ductless Systems Ductless systems contain the evaporator,
condenser condenser pad, and line set without any ductwork.
Can be a single piece or a split system.
Can be ordered with low ambient controls.
Very quiet and a quick install.

31. Ductless systems
Extremely efficient units, cool the space the evaporator is mounted in.
No thermostat is needed, uses a remote control or control set on the evaporator itself.
Tonnage available varies.
Sometimes allows more than 1 evaporator for a condenser.

32. Ductless systems