Leak Check and Evacuation) Leak Detection Tips

 

1. Using Your Senses: Look, Listen, and Touch

• Look for Signs of Oil:

  • Condensing Units: Look for oil stains on the fins of the condensing coil.
  • Why Oil? Refrigerant leaks often carry oil droplets from the compressor, which can leave visible stains.

• Listen for Leaks:

  • Initial Low-Pressure Test: Pressurize the system to 50 PSIG and listen for any hissing sounds.
  • Why 50 PSIG? It can reveal obvious leaks without using excessive nitrogen.

• Feel for Leaking Vapor:

  • Method: Wrap your hand around the suspected area and squeeze/release. Listen for changes in sound.

2. Check Obvious Places for Leaks

• Mechanical Connections:
  • Flared and Compression Fittings: Common leak points due to vibration.
• Schrader Valves:
  • Pre-Gauge Check: Remove caps and use an electronic leak detector.
  • Post-Gauge Check: Ensure valves haven’t been damaged during testing.
  • Temporary Fix: Replace the cap if the valve leaks. If persistent, replace the valve or O-rings.

3. Isolating Parts of the System

• Condensing Unit Leak Detection:

  • Method: Cover the condensing unit with plastic to block wind.
  • Probe: Place the electronic leak detector probe under the plastic. Wait 5-10 minutes to detect leaks.

• Evaporator Coil Leak Detection:

  • Accessing Case Coils: Remove the front cover for direct access.
  • Non-Case Coils: Remove the drain plug and insert the electronic leak detector probe into the drain opening.
  • Why Effective? Refrigerant is heavier than air and will collect at the bottom of the plenum, providing a clear detection point.

4. Isolating the Air Handler

• Pump Down Procedure:
  • Purpose: To isolate and check for leaks in the refrigerant lines and air handler.
  • Steps:
    1. Close Liquid Line Service Valve: Isolate the liquid line.
    2. Run Compressor: Allow it to pull refrigerant into the condensing coil.
    3. Monitor Low-Side Gauge: Close the suction line service valve as the needle approaches zero.
    4. Disconnect Power: Pull the disconnect to stop the compressor.
    5. Braise on Schrader Fittings: Prepare for pressure testing.
    6. Pressurize with Nitrogen: Bring system to 150 PSIG to check for leaks.

5. Advantages and Considerations

• Electronic Leak Detectors:

  • Pros: Quick and accurate, no need for system prep.
  • Cons: Can be affected by wind and require practice to use effectively.

• UV Leak Detectors:

  • Pros: Visual confirmation of leak location.
  • Cons: Requires direct visual access to the leak.

• Ultrasonic Leak Detectors:

  • Pros: Detects leaks through sound, useful in quiet environments.
  • Cons: Requires proximity to the leak source.

• Bubble Solution:

  • Pros: Simple and effective for pinpointing exact leak locations.
  • Cons: Requires system pressurization and manual application.