22
IM 725 (1-02)
Direct-Expansion R-22 (DX) Piping
DX coils have O.D. sweat connections. Interconnecting tubing is
field-supplied. See Table 17, page 24 and job-specific drawings for
correct tubing sizes.
Wrap TXV valve with a quenching cloth and remove bulb from
suction line to avoid valve damage while brazing.
CAUTION
!
Condensate piping:
AAF
®
-HermanNelson
®
cooling unit ventilators are designed for
condensate removal into a condensate disposal system. Do not connect
the unit drain connection so that condensate exits to the outside and/
or is exposed to freezing temperatures.
Installer is responsible for
any damage that might be caused from freezing condensate
. In
applications with an end compartment auxiliary drain pan, see the
installation instructions shipped with the auxiliary drain pan itself.
STOP! Before Brazing
TXV (Thermal Expansion
Valve) Protected From
Overheating
Bulb
Removed To
Prevent
Overheating
Damage
Use A Quenching Cloth
When Brazing, to Prevent
Overheating The TXV Valve
Body (Avoid Valve Damage
and Eratic Operation)
Figure 74 - Wrap TXV Valve Before Brazing
Proper ventilation is required for brazing. When brazing, be sure to
protect unit ventilator components from overheating damage (melting
insulation, also damage to valves, wiring, electronics, sensors, etc.).
During brazing, bleed nitrogen through the piping. Using field-
supplied material suitable for insulating refrigerant lines, wrap the
thermal expansion valve (TXV) bulb and the piping between the TXV
and the point where it enters the coil with at least one thickness of the
material. Likewise, insulate the suction line. (See figures 76 -80 for
typical piping and wiring)
Ensure proper insulation of supply and return piping. Proper insulation
prevents loss of unit ventilator capacity, overheating of end
compartment, and / or moisture dripping.
Piping Stub-up Within Cabinet
Unit End Compartment
Piping Stub-up Within 6" End Panel
End Panel 6"
Application and Dimension
Wall Line 11
1
⁄
2
10
3
⁄
4
Left End
of unit
(Less end panel)
Caution: Space available in left end
compartment for piping stub-up.
Stub-up including unions and shutoff
valves must disconnect below floor
line for unit installation and removal.
1
Space available at left end of unit
for piping stub-up when 6" end
panel is used.
Left End of unit
(Less end panel)
Wall Line
4
1
Unit End Compartment
6
All dimensions in inches
Figure 73 - Piping Stub-Up Details, 6" End Panel
