Refrigerant Metering Device; Manifold Gauge Set - Lennox HP21 Series Installation Instructions Manual

Brazing Connection Procedure
1 − Cut ends of the refrigerant lines square (free from nicks
or dents). Debur the ends. The pipe must remain
round, do not pinch end of the line.
2 − Before making line set connections, use dry nitrogen to
purge the refrigerant piping. This will help to prevent
oxidation and the introduction of moisture into the sys-
tem.
3 − Use silver alloy brazing rods (5 or 6 percent minimum
silver alloy for copper−to−copper brazing or 45 percent
silver alloy for copper−to−brass or copper−to−steel braz-
ing) which are rated for use with HCFC−22 refrigerant.
Wrap a wet cloth around the valve body and the copper
tube stub. Braze the line set to the service valve.
4 − Wrap a wet cloth around the valve body and copper
tube stub to protect it from heat damage during braz-
ing. Wrap another wet cloth underneath the valve body
to protect the base paint.
NOTE − The tube end must stay bottomed in the fitting
during final assembly to ensure proper seating, sealing
and rigidity.
5 − Install a field−provided thermal expansion valve (ap-
proved for use with HCFC−22 refrigerant) in the liquid
line at the indoor coil.

Refrigerant Metering Device

These units are used in check expansion valve systems
only. See the Lennox Engineering Handbook for approved
TXV match-ups and application information.
Check expansion valves equipped with Chatleff fittings
are available from Lennox. Refer to the Engineering
Handbook for applicable expansion valves for use with
specific match-ups.
If you install a check expansion valve with an indoor coil
that includes a fixed orifice, remove the orifice before
installing the check expansion valve.
See figure 12 for installation of the check expansion valve.
Failure to remove RFC orifice when installing an ex-
pansion valve on the indoor coil will result in improp-
er operation and damage to the system.
Metering Device Installation
distributor

Manifold Gauge Set

Use a manifold gauge set equipped with low loss" hoses
when checking the charge of the unit. Do not use A man-
ifold gauge set with anything other than low loss" hose.
See figure 13.
Page 11
IMPORTANT
o−ring
expansion
valve
o−ring
strainer
liquid line
stub
Figure 12