HVAC

Posted on October 2, 2012
Tags: misc

1 Terms

2 Service valve

2.1 OLD SYSTEMS

  • 3 openings
    • COMPRESSOR-PORT : Connects to the large line condenser outside
    • REFRIGERANT-PORT : Connects to the small line that travels to the evaporator inside
    • SERVICE-PORT : capped and used for maintenance
  • VALVE STEM is the service knob ususally square looking
  • VALVE STEM when untightened(BACKSEATED) fully counterclockwise
    • SERVICE-PORT becomes Closed
    • fluid flows btw COMPRESSOR-PORT and REFRIGERANT-PORT
  • VALVE STEM is tightened(FRONTSEATED) fully clockwise
    • REFRIGERANT-PORT becomes Closed
    • fluid flows btw COMPRESSOR-PORT and SERVICE-PORT

2.2 NEW SYSTEMS

New system are simple in the sense that Valve Stems basically act like a turn on button. NEVER turn it on until AFTER vacuuming and pumping refrigerant(if needed). After turning it on(backseat it), you leave it that way. Here is some extraneous info on valve stems:

  • VALVE STEM when untightened(BACKSEATED) fully counterclockwise
    • fluid flows through all 3 ports
  • VALVE STEM is tightened(FRONTSEATED) fully clockwise
    • COMPRESSOR-PORT becomes Closed
      • This isolates the Refrigerant from the Condenser from the Vapor line on the REFRIGERANT-PORT and SERVICE-PORT
    • fluid flows btw SERVICE-PORT and REFRIGERANT-PORT
  • Notice: SERVICE-PORT is ALWAYS Connected to the REFRIGERANT-PORT regardless if VALVE STEM is backseated or Frontseated.

2.2.1 Instruction for installing new Units

Compared to old systems the New systems have a service port called a “Shrader valve” with a “Shrader pin” which is INDEPENDENT of the VALVE STEM knob.

  • 2 components
    • Liquid line(small) is turned on and off by its own valve stem via a hexagon wrench knob
    • Vapor line(big) is turned on and off by its own valve stem via a hexagon wrench knob
      • Service port is on Vapor line, you use this port for both vacuum out air and pumping in refrigerant.
  • By default the 2 valve stems on the Liquid line and Vapor line are frontseated(counter clockwise).
  • The Vapor line when frontseated means that the default pre-installed refrigerant inside the condenser coil outside is isolated from the Vapor line that is traveling to the inside unit.

NEVER TURN ON ANY OF THE VALVE STEMS UNTIL THE FINAL STEP!!

First you vacuum out the air in the Vapor line then you Pump in refrigerant into the Vapor line. Finally you can turn on both Valve Stems on the Vapor line and Liquid Line.

2.2.1.1 Vacuum out the Vapor line(Big line) and pump refrigerant

The Service port uses schrader pin. The Service port is the only port you need to access (if you are picking up a hexagonal wrench you are doing something wrong)

Note: If the line length isnt too long, typically you dont need to pump refrigerant BUT you always have to vacuum the system.

  1. Typically for new systems, the condenser unit outside comes with refrigerant. This is sealed off in the condenser unit outside and the VALVE STEM is by default FRONTSEATED.
  2. So DO NOT BACKSEAT(turn counterclockwise) the VALVE STEM even after connecting the Vapor line to the Refrigerant-PORT since it is filled with air.
  3. Vacuum out this air in the refrigant line to the evaporator by connecting to the SERVICE-PORT Shrader pin.
  4. Connect the middle hose from the digital manifold to the vacuum engine
  5. Connect the high side to the SERVICE PORT typically located Vacuum using the digital manifold, until ~400-500 microns.
  6. Close the high side knob on the digital manifold and check for 10 minutes to see if the microns jump up rapidly indicating a leak. While checking you can turn off the vacuum engine.
  7. Next be prepared to pump refrigerant or if not needed to pump refrigerant, just disconnect all the hoses, but remove the hose quickly so less refrigerant leaks.
  8. With the current configuration (middle hose from digital manifold to vacuum, high side hose to the service port) disconnect the middle hose completely both ends from the vacuum and digital manifold
  9. With the disconnected hose, connect it to the refrigerant tank
  10. Turn on and off the knob on the refrigerant tank to let the air in the hose pump out
  11. Connect the hose to the middle of the digital manifold
  12. put the tank on a scale (use the scale to check how many oz of refrigerant you have pumped)
  13. Turn on the high side knob and monitor the scale to see how much refrigerant was pumped
  14. Turn off the knob on the refrigerant tank
  15. Close the knob on the high side, and disconnect the high side hose connected to the service port quickly to prevent refrigerant from leaking
  16. cap the service port,
  17. unscrew the cap to the Valve Steps for both the liquid line and suction line
  18. Use a hexagon wrench to backseat(counter clockwise turn) both liquid line and suction line to start the system and let refrigerant flow throughout the system