Greenheck DGX Installation, Operation And Maintenance Manual page 16

Installation - Direct Expansion (DX) Coil Piping (Optional)
Step 1 Verify Nozzle Placement
Inspect the refrigerant distributor and verify that the
nozzle is in place. The nozzle is generally held in
place by a retaining ring or is an integral part of the
distributor itself. See figure #31.
NOTE!
If a hot gas bypass kit was ordered, the nozzle
will not be located in the distributor, it will be
located in the hot gas bypass kit.
Step 2 Install the Optional Hot Gas Bypass Kit (By Others)
If a hot gas bypass kit was ordered with the coil, install it now. Consult the IOM from the bypass kit supplier for
complete installation instructions. Align the side port with the hot gas line prior to brazing into place. Refer to
figure #30.
Step 3 Install Suction Line
Install a suction line from the compressor to the suction connection. See figures #29 and #30.
Step 4 Install the Thermal Expansion Valve (TEV) (By Others)
Follow the TEV manufacturer's recommendations for installation to avoid damaging the valve. If the valve is
externally equalized, use a tubing cutter to cut off the plugged end of the factory installed equalizer line. Use a
de-burring tool to remove any loose metal from the equalizer line and attach it to the TEV. If the valve is
internally equalized, the factory installed equalizer line can be left as is. See figures #29 and #30.
Step 5 Mount the Remote Sensing Bulb (By Others)
The expansion valve's remote sensing bulb should be securely strapped to the horizontal run of the suction line
at the 3 or 9 o'clock position and insulated. See figures #29 and #30.
Step 6 Check Coil Piping for Leaks
Pressurize the coil to 100 psig with dry nitrogen or other suitable gas. The coil should be left pressurized for a
minimum of 10 minutes. If the coil holds the pressure, the hook-up can be considered leak free. If the pressure
drops by 5 psig or less, re-pressurize the coil and wait another 10 minutes. If the pressure drops again there is
likely one or more small leaks which should be located and repaired. Pressure losses greater than 5 psig
indicate a large leak that should be isolated and repaired.
Step 7 Evacuate and Charge the Coil
Use a vacuum pump to evacuate the coil and any interconnecting piping that has been open to the atmosphere.
Measure the vacuum in the piping using a micron gauge located as far from the pump as possible. Evacuate the
coil to 500 microns or less then close the valve between the pump and the system. If the vacuum holds to 500
microns or less for one minute, the system is ready to be charged or refrigerant in another portion of the system
can be opened to the coil. A steady rise in microns would indicate that moisture is still present and that the coil
should be further vacuumed until the moisture has been removed.
Failure to obtain a high vacuum indicates a great deal of moisture or a small leak. Break the vacuum
with a charge of dry nitrogen or other suitable gas and recheck for leaks. If no leaks are found,
continue vacuuming the coil until the desired vacuum is reached.
Step 8 Install the Drain Line
Connect an unobstructed drain line to the drain pan.
A trap should be used to prevent sewer gas from
being drawn into the unit. See figure #32.
IMPORTANT!
All traps must be installed below the roofline or
be otherwise protected from freezing.
Retainer
Ring
Figure 31. Nozzle Placement
NOTE!
Figure 32. Drain Trap
16
Nozzle Distributor
6 in. min.
6 in. min.