4
Unitary Products Group
RE–ASSEMBLING, BRAZING AND
CLEANING OF JOINT CONNECTIONS
When using hard solder, an inert gas such as dry ni-
trogen must be introduced and permitted to flow
through tubing during brazing to displace air and
prevent oxidation.
Remove the Schrader valve cores from the service
valves. Remove the plugs from the service valve field
tubing connections. Clean the joints to be brazed.
NOTE: Do not overheat the connection to be brazed as
this can cause improper flow of solder, resulting
in a weak and leaking joint. Never apply heat
directly to face of fitting. Do not heat solder by
direct contact with flame of the torch.
When brazing copper tubing it is very important to pre-
heat the entire joint before applying the solder. This is
done by sweeping the flame steadily and evenly around
the fitting, to bring both fitting and tubing up to equal tem-
perature before applying the solder.
Reassemble groups of tubing and fittings, brazing sever-
al joints instead of one joint at a time. This reduces the
chance for error in the alignment of the assembly. Re-
place schrader valve cores. DO NOT OPEN SERVICE
VALVES AT THIS TIME.
NOTE: Do not heat solder by direct contact with flame of
the torch.
INSULATION OF VAPOR LINE
Insulate vapor line with 3/8” (or that required by local
code) closed cell insulation.
Slide tubing insulation onto the vapor line so that it is cov-
ered completely from the indoor coil to the outdoor unit.
Be sure that the tubing is capped before sliding on insula-
tion.
It is not necessary to insulate the liquid line.
FIGURE 2 – INSULATION OF VAPOR LINE
INCORRECT
CORRECT
LIQUID
LINE
TAPE
SHEET METAL HANGER
INSULATED VAPOR LINE
ÎÎÎ
ÎÎÎ
ÎÎÎ
ÎÎÎ
ÎÎÎ
ÎÎÎ
ÉÉ
ÉÉ
ÎÎ
ÎÎ
ÎÎÎ
ÎÎÎ
ÎÎÎ
ÎÎÎ
NOTE: In areas of extreme temperatures and humidity,
additional insulation may be required to prevent
excessive condensation and loss of capacity.
Do not insulate liquid line and vapor line together. Liquid
line should not be in contact with the vapor line. See Fig-
ure 2.
REFRIGERANT LINE SUPPORT
Refrigerant lines should be supported in a way that no
dips or sags occur. We recommend four feet between
supports. If refrigerant lines are to be attached to the
home structure, care should be taken to eliminate the
transmission of vibrations. Attach the refrigerant lines to
the indoor coil first. Remove plugs from the indoor coil,
then clean joints to be brazed. Braze refrigerant lines to
the indoor coil. Attach refrigerant lines to the outdoor unit.
CHARGING AND LEAK TESTING
On systems with or without service valves the refrigerant
should be recovered or recycled in accordance with EPA
regulations. In some cases this may require putting pierc-
ing valves on both the high and low sides of the system.
DO NOT vent refrigerant to the outdoors.
When recovering refrigerant from a system, with a burn-
out, follow a safe procedure due to possible contamina-
tion.
Avoid getting the refrigerant in the eyes or on the
skin.
Contaminated refrigerant must be recovered and re-
turned to the local refrigeration supply house for proper
disposition.
TOTAL LINE LENGTH
Units should be installed only with approved system com-
bination (indoor/outdoor) as specified in the Technical
Guide.
For systems with total line length exceeding 50 feet, see
APPLICATION DATA, 690.01–AD1V(1296) and work-
sheet 690.01–AD1.1V(791) “General Piping Recom-
mendations and Refrigerant Line Length” for vapor and
liquid line sizing, calibration of liquid line pressure loss or
gain, determination of vapor line velocity, elevation limita-
tions, orifice connections, system charging, traps, etc.
System with liquid line pressure loss or gain grater than
11 psi must be provided with corrected orifice size as
noted in Form 690.01 – AD1V (1296).
ORIFICE SELECTION
NOTE: The proper orifice must be installed in the indoor
coil liquid line connection prior to the connection
of the refrigerant lines.
The indoor coil is under 35 psig (inert gas) pressure.
