5-565.1
10
The cooling section includes a full coverage, 3-way sloping
409 stainless steel drain pan to remove condensate from coil
headers, thermal expansion valves, and refrigerant piping.
Insulation is standard on outdoor units and optional on indoor
units and double wall construction is optional on all units. The
cabinet includes two doors, a removable upper door for service
access to the coil once the plumbing has been installed and a
lower door which includes a factory supplied 1" stubbed drain
connection to the exterior of the cabinet. Field connections for
coil inlet and outlet piping can be made through the cabinet
corner post or back of the unit. The cooling section duct
transition includes 1-1/2" flanges for fastening the sides of
the coil. The bottom duct transition is angled to remove any
condensation that may be entrained in the supply air stream.
For field supplied coils, do not exceed the maximum coil
dimensions listed in Literature 82-135. The dimensions listed
are for the maximum coil dimensions. If the coil supplied is
smaller than the listed dimensions, field supplied blank off
plates are required to prevent air bypass around the coil. The
coil is supported by two 14 gauge support rails which contain
mounting provisions for fastening 4", 5", 6", 7.5", 8.5", and
10" deep coils. When obtaining the specifications from a coil
manufacturer, it is important to obtain the pressure drop through
the coil so that the proper motor horsepower can be selected.
For Both Chilled Water and Direct Expansion Coils: The
condensate drain line needs to include a P-trap immediately
downstream of the connection to the unit. This trap should
extend at least two inches below the connection to prevent
air pressure from forcing air into the unit. The trap should be
primed with a water/glycol solution to prevent freezing. All points
where refrigerant, water or condensate lines enter the structure
should be sealed and vibration dampened. Include shut-off
valves to isolate the cooling coil from the system in order to
remove the coil for service or replacement without draining the
entire system. For additional guidelines, refer to the ASHRAE
Fundamentals Handbook section of piping recommendations.
direct expansion (dX) Piping
The refrigerant lines should be insulated to prevent warming
or cooling of the refrigerant. If the suction line is allowed to be
cooled, liquid will condense in the line and can severely damage
the compressor. If the liquid line is warmed, the refrigerant
can "flash" into a gas. This will cause erratic operation of
the expansion device and impair the heat transfer ability of
the cooling coil. Long runs of piping need to be periodically
supported to prevent excess vibration that can damage the
piping and joints. It is recommended to provide dampening
supports at intervals of length equivalent to 15 tube diameters.
figure 10.2 - general dX Piping
1. Inspect the refrigerant distributor and verify that the nozzle
is in place.
2. All field brazing and welding should be performed using
high quality materials and an inert gas purge (such as
nitrogen) to reduce oxidation of the internal surface of the coil.
3. Connect the suction line and suction connection.
4. Install the expansion valve (By Others). Follow the
expansion valve manufacturer's recommendations for
installation to avoid damaging the valve.
5. 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.
6. Connect the liquid line to the expansion valve. Pressurize
the coil, expansion valve assembly and suction connection
to 100 psig with dry nitrogen or other suitable gas. The coil
should be left pressurized for a minimum of 10 minutes.
7. If the coil holds pressure, the hook-up can be considered
leak free. If the pressure drops by 5 psi or less,
repressurize the coil and wait another 10 minutes. If the
pressure drops again, there are more than likely one or
more small leaks, which should be located and repaired.
Pressure losses greater than 5 psi would indicate a larger
leak, which should be isolated and repaired. Be sure to
check valves and fittings as potential sites for leakage or
bleed. If the coil is found to be leaking, contact your local
factory representative.
figure 10.1 - cooling section
Optional double
wall construction
DX single circuit (shown) and
dual circuit coils available
Optional Factory
Installed
DX or Chilled
Water coil.
Fin spacings
of 6,8,10,12
or 14 fins per
inch
Adjustable
mounting bracket
for 2,3,4 and 6
row coils
Full coverage
3-way sloping
409 stainless
steel drain pan
1” stubbed drain
connection
Right or left hand coil
header access to
match gas controls
unit installation
unit installation
Suction Line
Expansion Valve
Remote Sensing Bulb
Straps
Suction Connection
Coil
Suction Header
Distributor
Equalizer Line
Nozzle
Liquid Line
(By Others)
