HVAC Supplies : Line Sets

 

• Line Sets:

  • Function: Carry refrigerant between the outdoor and indoor units in an HVAC system.
  • Components:
    • Standard Split System:
      • Insulated Suction Line (carries low-pressure gas).
      • Uninsulated Liquid Line (carries high-pressure liquid).
    • Mini Split System:
      • Uses a dual insulated line set where both the suction and liquid lines are insulated.
  • Material: Made of copper.
  • Sizing:
    • Sizes are indicated by the diameter of the liquid line, suction line, and length.
    • Example: 3/8 3/4 50 means a 3/8 inch liquid line, 3/4 inch suction line, and 50 feet length.

• Custom vs. Pre-Cut Line Sets:

  • Contractors may build their own line sets using soft copper and insulation.
  • Pre-cut sets are also available and are connected to units by brazing.

• Brazing Process:

  • Purpose: Permanently bonds copper line sets to indoor and outdoor units.
  • Supplies Needed:
    • Nitrogen: Used to pressurize and "sweep" the inside of the line set, preventing scale formation during brazing.
    • Oxygen and Acetylene: Used to produce a high-temperature flame for brazing.
    • Silver Solder: Joining compound (usually 15% silver) that seals the copper connections.
    • Mesh Cloth and Flux: Prepare and clean the copper surfaces before brazing.
  • Alternatives:
    • Mini split systems often use flare fittings instead of brazing.
    • Thermostat Wire: Typically taped to the line set for connection between indoor and outdoor units.

• Line Set Flushing:

  • Flush: A chemical used to clean the inside of a line set, especially when switching to a new system or refrigerant type.