Installation manual
9
Table 2 – 38AUQ*16--25 Piping Recommendations (Two-Circuit Unit)
R -410A Equivalent Length
Model
Nomi nal Capacit y
Length Equiv 0-38 38-75 75-113 113-150 150-188
Length Lin 0-25 25-50 50-75 75-100 100-125
38AUQ*16 Liquid Line
1
/
2
1
/
2
1
/
2
1
/
2
1
/
2
Max Lift
Cool 25 50 75 100 125
Heat 25 50 60 60 60
Vapor Line 1
1
/
8
1
1
/
8
1
1
/
8
1
1
/
8
1
1
/
8
Charge ea. (lbs) 20.9 22.8 24.8 26.6 28.6
38AUQ*25 Liquid Line
1
/
2
1
/
2
5
/
8
1
/
2
5
/
8
5
/
8
5
/
8
Max Lift
Cool 25 37 50 24 51 48 63
Heat 25 50 50 60 60 60 60
Vapor Line 1
1
/
8
1
1
/
8
1
1
/
8
1
1
/
8
1
3
/
8
1
3
/
8
Charge ea. (lbs) 26.9 28.8 30.7 30.7 33.6 37.1 40.2
Legend:
Leng t h Equiv Equivalent tubing length, including effects of refrigeration specialties devices
Linear Lin T ypical linear tubing length, Feet (50% added to linear to define Equivalent Length for this table)
Liquid Line Tubing size, inches OD.
Max Lift Maximum liquid lift (indoor unit ABOVE outdoor unit only), at maximum permitted liquid line pressure drop —
S Linear Length Less than 100 ft: Minimum 2.0°F subcooling entering TXV
S Linear Length Greater than 100 ft: Minimum 0.5°F subcooling entering TXV
Vapor Line Tube size, inches OD
Charge Charge Quantity, lbs. Calculated for both liquid line sizes (where applicable), but only with larger suction line size
(where applicable)
NOTE: For applications with equivalent length greater than 188 ft (57 m) and/0r linear length greater than 125 ft (38 m),
contact your local Carrier representative.
Check Vertical Separation —
If there is any vertical separation between the indoor and
outdoor units, check to ensure that the separation is within
allowable limits. Relocate equipment if necessary.
Provide Safety Relief —
If local codes dictate an additional safety relief device,
purchase locally and install locally. Installation will
require the recovery of the factory shipping charge before
the factory tubing can be cut and the supplemental relief
device is installed.
Refrigerant Line Sizing —
Consider the length of the piping required between the
outdoor and indoor units. The maximum allowable line
length is 100 ft (30.5 m). See Table 2. Refrigerant vapor
piping should be insulated.
Install Filter Driers and Moisture Indicators —
Every unit MUST have bi-directional filter driers in the
liquid lines. Locate the filter driers at the indoor unit,
close to the evaporator coil’s thermal expansion valve
(TXV) inlets.
38AUQ units include two Puron-duty filter driers, shipped
in cartons attached to the unit basepan. Remove the filter
driers and prepare to install in the liquid lines at the
evaporator coil. Do not remove connection fitting plugs
until ready to connect and braze the filter driers into the
liquid line positions See Table 3.
IMPORTANT: A refrigerant receiver is not
provided with the unit. Do not install a receiver.
Installation of liquid line moisture indicating sightglass in
each circuit is recommended. Locate the sightglass(es)
between the outlet of the filter drier and the TXV inlet.
Refer to Table 4 for recommendations on refrigeration
specialties.
Select the filter drier for maximum unit capacity and
minimum pressure drop. Complete the refrigerant piping
from the indoor unit to the outdoor unit before opening
the liquid and suction lines at the outdoor unit.
38AUQ