Lecture Notes: Air Handler and Evaporator Coil

Components of Air Handler and Evaporator Coil

• Air Handler and Evaporator (Indoor Coil)
  • Gas furnace: evaporator coil on top.
  • Heat pump: blower on top, then evaporator coil.
  • Heat transfer: air is moved across the coil to add or remove heat.

Heat Pump and Coil Operations

• Heat Pump
  • Auxiliary heat adds more heat to air after passing through the evaporator coil.
  • Orientation: evaporator coil before blower for most manufacturers.
• Terminology
  • Air Conditioning: evaporator coil (indoor), condensing coil (outdoor).
  • Heat Pump: indoor coil, outdoor coil (roles change based on mode).
    • Heating mode: indoor coil = condenser, outdoor coil = evaporator.
    • AC mode: indoor coil = evaporator, outdoor coil = condenser.

Installation and Drainage

• Drain Line
  • Drain line with a natural slope; unit must be installed level.
  • Two ports: main drain line (lower port) and auxiliary port (halfway blocked).
  • Importance of a drain trap for proper water flow.

Safety and Maintenance

• Float Switch
  • Adjust float switch for low water level activation.
  • Safety switch prevents system overflow by shutting off the thermostat.
• Opinions on Installation
  • Float switch location varies; adjustments are crucial.
  • Different installation preferences (e.g., Ford vs. Chevy analogy).

Multi-Positional Coil

• Coil Positioning
  • Multi-positional coil functions in various orientations (e.g., horizontal for attic).
  • Drain pan design supports primary and secondary drainage.
  • Factory plugs: partially blocked for overflow, full flow for main drainage.

Connection and Absorption

• Drain Line Connections
  • All connections should be glued; use primer and glue for strong bonds.
  • Rubber hose usage: absorbs vibrations, prevents PVC breakage, eases maintenance.

Functionality and Maintenance

• Thermodynamic Processes
  • Cooling mode: refrigerant flows, changes from liquid to vapor, superheated back to compressor.
  • Heating mode: refrigerant flows in reverse, de-superheats and sub-cools.
• Humidity and Bacteria
  • Moisture retention can cause bacteria growth ("dirty sock syndrome").
  • UV light installation can prevent bacterial growth and extend system life.

Additional Considerations

• Humidity Concerns
  • Increased maintenance may be needed for the blower due to moisture retention.
  • UV light recommendation for bacterial control and system longevity.

Summary

Understanding the components, installation requirements, and operational dynamics of air handlers and evaporator coils is essential for effective maintenance and optimal performance in HVAC systems. Proper installation, safety measures, and attention to moisture control will enhance longevity and prevent issues such as bacterial growth.