520413-BIM-A-0209
Johnson Controls Unitary Products
11
Drain Connections
All drain lines MUST be trapped and located so they will not be
exposed to freezing temperatures.
All evaporator blower units have a 3/4” PVC condensate stub at
the end of a double sloped drain pan. The drain pan is
removable and reversible, It can be unscrewed and slid out
from one side of the evaporator section and installed in the
other end.
Drain piping should be constructed as shown in Figure 6. The
3-inch dimension must equal or exceed the negative static
pressure developed by the supply air blowers. If it does not, the
condensate will not drain properly and may overflow the drain
pan.
Figure 6: Recommended Drain Piping
Refrigerant Mains
Line Sizing
When sizing refrigerant pipe for a split-system air conditioner,
check the following:
1.
Suction line pressure drop due to friction.
2.
Liquid line pressure drop due to friction.
3.
Suction line velocity for oil return.
4.
Liquid line pressure drop due to vertical rise. For certain
piping arrangements, different sizes of suction line pipe
may have to be used. The velocity of the refrigerant vapor
must always be great enough to carry the oil back to the
compressor.
5.
Evaporator Located Below Condenser
- On a split
system where the evaporator blower is located below the
condenser, the suction line must be sized for both pressure
drop and for oil return.
6.
Condenser Located Below Evaporator
- When the
condenser is located below the evaporator blower, the
liquid line must be designed for the pressure drop due to
both friction loss and vertical rise. If the pressure drop due
to vertical rise and friction exceeds 40 psi, some refrigerant
will flash before it reaches the thermal expansion valve.
Flash gas:
1.
Increases the liquid line pressure loss due to friction that in
turn causes further flashing.
2.
Reduces the capacity of the refrigerant control device
which starves the evaporator.
3.
Erodes the seat of the refrigerant control device.
4.
Causes erratic control of the refrigerant entering the
evaporator.
Take Adequate Precautions
Many service problems can be avoided by taking adequate
precautions to provide an internally clean and dry system and
by using procedures and materials that conform to established
standards.
Use hard drawn copper tubing where no appreciable amount of
bending around pipes or other obstructions is necessary. If soft
copper is used, care should be taken to avoid sharp bends that
may cause a restriction. Pack fiberglass insulation and a
sealing material such as permagum around refrigerant lines
where they penetrate a wall to reduce vibrations and to retain
some flexibility.
Support all tubing at minimum intervals with suitable hangers,
brackets or clamps.
Braze all copper-to-copper joints with Silfos-5 or equivalent
brazing material. Do not use soft solder. Insulate all suction
lines with a minimum of 1/2" ARMAFLEX or equivalent. Liquid
lines exposed to direct sunlight and/or high temperatures must
also be insulated. Never solder suction and liquid lines
together. They can be taped together for convenience and
This Split-System (Air Condensing / Heat Pump / Air
Handling) unit is one component of an entire system. As
such it requires specific application considerations with
regard to the rest of the system (air handling unit, duct
design, condensing unit, refrigerant piping and control
scheme).
Failure to properly apply this equipment with the rest of
the system may result in premature failure and/or
reduced performance / increased costs. Warranty
coverage specifically excludes failures due to improper
application and Unitary Products specifically disclaims
any liability resulting from improper application.
Please refer to the equipment Technical Guide,
Installation Manual and the piping applications bulletin
247077 or call the applications department for Unitary
Products @ 1-877-UPG-SERV for guidance.
3" MINIMUM
¾” PVC
STUB
FIELD SUPPLIED
