Installation manual

IM-487 Page 25
Figure 26. Condensate Drain Connection
Field Refrigerant Piping and
Charging of DX Coils
Units that ship from the factory with DX coils installed do
not include refrigerant piping or refrigerant controls. The coil
assembly is ready for field connections at the distributors and
at the suction headers. Piping kits that provide the necessary
liquid and hot gas piping and control components are avail-
able for field installation. Field installed refrigerant piping
may exit the unit cabinet at one of the following locations:
1. Through the floor of the unit.
2. Through the discharge and bulkhead of the unit.
3. Through a cabinet door near the DX coil that is not
required for service areas.
In preparing for field piping, the plastic plugs on the distribu-
tors must be removed and the copper caps at the suction
header connections must be unsweated.
Follow piping design, sizing, and installation information
presented in ASHRAE handbooks in the design and installa-
tion of interconnecting piping. The DX coil and condensing
unit are intended to be set at the same elevation, as close as
possible to each other to minimize refrigerant pressure drop.
Design piping to prevent liquid refrigerant carryover to the
compressor and to provide a continuous return of compressor
oil from the system.
Piping Recommendations
1. Use type K or L clean copper tubing. Clean and braze all
joints thoroughly with high temperature solder.
2. Base piping sizes on temperature/pressure limitations as
recommended in the following paragraphs. Under no cir-
cumstances base pipe size strictly upon coil or condensing
unit piping connection size.
3. Suction line piping pressure drop should not exceed the
pressure equivalent of 2°F (1°C), 3 psi (20.7 kPa) per 100
feet (30.5 m) of equivalent pipe length. After the suction
line size has been determined, check the vertical suction ris-
ers to verify that oil will be carried up the riser and back to
the compressor. Pitch the suction line(s) in the direction of
refrigerant flow and support adequately. Lines should be
free draining and fully insulated between the evaporator
and the compressor.
4. Check vertical suction risers to determine the minimum ton-
nage required to carry oil up suction risers of various sizes.
5. Insulate suction lines inside the unit cabinet to prevent
condensation.
6. Size the liquid line for a pressure drop not to exceed the
pressure equivalent of 2°F (1°C), 6 psi (41.4 kPa) satu-
rated temperature.
Table 5: Minimum tonnage (R-22) to carry oil up suction
riser at 40°F saturated suction
CAUTION
For any of the above cabinet penetrations, the hole
must be tightly sealed to prevent water or air leakage.
S t a t i c P r e s s u r e " P "
( i n . w . o . )
D r a i n P a n
4 " ( 1 0 2 m m )
M i n i m u m
" A "
8 " ( 2 0 3 m m )
M i n . o r 2 x " P "
M i n i m i z e T h i s
D i m e n s i o n
8 E A M  )
N o t e : D r a i n l i n e m u s t
n o t b e r u n h i g h e r
t h a n t h i s l e v e l
C o p p e r T u b e
( o n e e a c h e n d o f c o i l )
S e e V i e w " A "
CAUTION
The pounds of refrigerant in the system may exceed
the capacity of the condenser, depending on the
amount of refrigerant in the liquid lines between the
DX coil and the condensing unit.
Refer to condenser manufacturer for information about
refrigerant capacity. Suitable means of containing the
refrigerant is required.
CAUTION
On systems with optional hot gas bypass, it is
important the bypass solenoid valve be located at
the condensing unit and not at the DX coil to prevent
liquid return and damage to the compressor.
LINE SIZE
O.D.
1-1/8" 1-3/8" 1-5/8" 2-1/8" 2-5/8" 3-1/8" 3-5/8" 4-1/8"
MIN.
TONS
1.5 2.5 3.8 7.6 13.10 20.4 29.7 41.3