• Where the return air duct is short or sound may
be a problem, use acoustical duct liner inside the
duct. You must insulate duct work that runs through
an unheated space during the heating season or
an uncooled space during the cooling season. It
is best practice to use a vapor barrier to prevent
absorption of moisture from the surrounding air into
the insulation.
• Correctly size the supply air duct by using a
transition to match the unit opening. Suspend
all ducts using flexible hangers and never fasten
ducts directly to the structure. Fabricate and install
duct work in accordance with local and/or national
codes. This includes the standards of the National
Fire Protection Association for Installation of Air
Conditioning and Ventilating Systems, NFPA No. 90B.
CAUTION
Equipment should never be operated without filters.
Connecting the condensate drain
Adhere to the following:
• Pitch all drain lines 1/4 in./ft away from the unit
drain pan and make sure that the drain lines are no
smaller than the coil drain connection.
• Route the drain line so that it does not impede
access to the coil, furnace, air handling system, or
filter and is not exposed to freezing temperatures.
• Instruct the homeowner that the indoor coil drain
pan must be inspected and cleaned regularly to
prevent odors and ensure proper drainage.
NOTICE
For XAF and XAH coils, when the coil is installed in
an attic or above a finished ceiling, an auxiliary drain
pan must be provided under the coil as is specified by
most local building codes.
• Install the coil level or pitched slightly toward the
drain end. Suggested pitch must not exceed 1/4 in./
ft of coil.
• Note that you can remove drain plugs using a
standard 3/8-in. drive socket ratchet.
• If the coil has a secondary drain, pipe it to a location
that gives the occupant a visual warning that the
primary drain is clogged. If a secondary drain is not
used, you must plug the secondary drain. See Figure
39, Figure 40, Figure 41, or Figure 42.
CAUTION
Avoid double trapping.
CAUTION
Threaded drain connections should be hand
tightened, plus no more than one turn.
• Do not use PTFE tape, pipe thread compound, or
other sealants. Use of a sealant can cause damage
and premature failure of the drain pan.
NOTICE
If the coil is installed in a draw-through application
(modular blower), the installer must trap the primary
and secondary drain line. If the secondary drain line is
not used, it must be plugged.
Connecting refrigerant lines
About this task:
CAUTION
Coil is under inert gas pressure. Relieve pressure
from coil by depressing Schrader core at end of
suction manifold stub out.
CAUTION
Dry nitrogen should always be supplied through
the tubing while it is being brazed, because the
temperature required is high enough to cause
oxidation of the copper unless an inert atmosphere
is provided. The flow of dry nitrogen should continue
until the joint has cooled. Always use a pressure
regulator and safety valve to insure that only low
pressure dry nitrogen is introduced into the tubing.
Only a small flow is necessary to displace air and
prevent oxidation.
Installation Manual: XAF, XAH, and XAU Series - Full Cased and Uncased Coils for Cooling and Heat Pumps
27
Johnson Controls Ducted Systems
