Operating Gauge Set; General - Lennox Signature XP21 Series Installation And Service Procedure

IMPORTANT
This unit must be matched with an indoor coil as
specified in Lennox' Engineering Handbook. Coils
previously charged with HCFC−22 must be flushed.
WARNING
This product and/or the indoor unit it is matched with may
contain fiberglass wool.
Disturbing the insulation
maintenance, or repair will expose you to fiberglass wool
dust. Breathing this may cause lung cancer. (Fiberglass
wool is known to the State of California to cause cancer.)
Fiberglass wool may also cause respiratory, skin, and
eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets available
from address shown below, or contact your supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900
CAUTION
Physical contact with metal edges and corners while
applying excessive force or rapid motion can result in
personal injury. Be aware of, and use caution when
working nearby these areas during installation or while
servicing this equipment.
WARNING
Electric Shock Hazard. Can cause injury
or death. Unit must be grounded in
accordance with national and local
codes.
Line voltage is present at all components
when unit is not in operation on units with
single-pole contactors. Disconnect all
remote electric power supplies before
opening access panel. Unit may have
multiple power supplies.

Operating Gauge Set

These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
who have jurisdiction before installation.
TORQUE REQUIREMENTS
When servicing or repairing HVAC components, ensure
the fasteners are appropriately tightened. Table 1 lists
torque values for fasteners.
XP21
during installation,
Page 6
IMPORTANT
Only use Allen wrenches of sufficient hardness (50Rc −
Rockwell Harness Scale minimum). Fully insert the
wrench into the valve stem recess.
Service valve stems are factory−torqued (from 9 ft−lbs for
small valves, to 25 ft−lbs for large valves) to prevent
refrigerant loss during shipping and handling. Using an
Allen wrench rated at less than 50Rc risks rounding or
breaking off the wrench, or stripping the valve stem
recess.
See the Lennox Service and Application Notes #C−08−1
for further details and information.
IMPORTANT
To prevent stripping of the various caps used, the
appropriately sized wrench should be used and fitted
snugly over the cap before tightening.
Table 1. Torque Requirements
Parts Recommended Torque
Service valve cap 8 ft.− lb.
Sheet metal screws 16 in.− lb.
Machine screws #10 28 in.− lb.
Compressor bolts 90 in.− lb.
Gauge port seal cap 8 ft.− lb.
USING MANIFOLD GAUGE SET
When checking the system charge, only use a manifold
gauge set that features low loss anti−blow back fittings.
Manifold gauge set used with HFC−410A refrigerant sys-
tems must be capable of handling the higher system
operating pressures. The gauges should be rated for use
with pressures of 0 − 800 psig on the high side and a low
side of 30" vacuum to 250 psig with dampened speed to
500 psi. Gauge hoses must be rated for use at or up to 800
psig of pressure with a 4000 psig burst rating.
OPERATING SERVICE VALVES
The liquid and vapor line service valves are used for re-
moving refrigerant, flushing, leak testing, evacuating,
checking charge and charging.
Each valve is equipped with a service port which has a fac-
tory−installed valve stem. Figure 2 provides information on
how to access and operating both angle and ball service
valves.

General

The XP21 is a high efficiency residential split−system heat
pump unit, which features a two−stage scroll compressor
and HFC−410A refrigerant. Units are available in 2, 3, 4 and
5−ton sizes. The series is designed for use with an expan-
sion valve only (approved for use with HFC−410A) in the
indoor unit.
11 NM
2 NM
3 NM
10 NM
11 NM