Section 1. General Requirements For All Long Line Set Applications - Daikin RR20AVAK9 Installation & Service Reference

SECTION 1. GENERAL REQUIREMENTS FOR ALL LONG LINE SET APPLICATIONS

1. Equivalent length must be used to determine acceptability of any long line set application. See Section 5 for equivalent
length calculations.
2. For any residential split system installed with a long line set, 3/8" liquid line size must be used.
Limiting the liquid line size to 3/8" is critical since an increased refrigerant charge level from having a larger liquid
line could possibly shorten a compressor's life-span.
a. Exceptions for air conditioning (cooling only) applications, 1/4" liquid line may be used in:
i. 1.5 ton applications for up to 100 equivalent feet (30.5 equivalent meters) with maximum 40'
(12.2 m) vertical lift
ii. 2.0 ton applications for up to 75 equivalent feet (22.9 equivalent meters) with maximum 20'
(6.1 m) vertical lift
b. Exceptions for air conditioning (cooling only) applications, 5/16" liquid line may be used in:
i. 1.5 ton applications for up to 250 equivalent feet (76.2 equivalent meters) with maximum 60'
(18.3 m) vertical lift
ii. 2.0 ton applications for up to 200 equivalent feet (61.0 equivalent meters) with maximum 40'
(12.2 m) vertical lift
iii. 2.5 ton applications for up to 175 equivalent feet (53.3 equivalent meters) with maximum 30'
(9.1 m) vertical lift
3. Most refrigerant tubing kits are supplied with 3/8" (9.5 mm) thick insulation on the suction line. For long line installations
over 80 feet (24.4 m) , if the line set passes through a high ambient temperature zone, 1/2" (12.7 mm) thick suction
line insulation is required to reduce loss of capacity. The liquid line must be insulated if more than 50 feet (15.2 m) of
liquid line will pass through an area that might reach temperatures of 30°F or higher than outdoor ambient. Never
attach a liquid line to any uninsulated portion of the suction line.
4. A crankcase heater must be installed on any compressor (if crankcase heater is not already factory installed).
5. Hard start assist kit is required.
6. Use of a thermostatic expansion valve (TXV) is required in all long line set applications. Unit must be charged to 7 to
9 ºF subcooling at the indoor unit.
7. Maximum equivalent length of line set is:
a. 250 feet (76.2 m) for single stage units with scroll or reciprocating compressors.
b. 150 feet (45.7 m) for single stage units with rotary compressors.
c. 150 feet (45.7 m) for two stage units.
8. Maximum linear length of line set is:
a. 200 feet (61.0 m) for single stage units with scroll or reciprocating compressors.
b. 150 feet (45.7 m) for single stage units with rotary compressors.
c. 150 feet (45.7 m) for two stage units.
9. Low voltage wiring. Verify low voltage wire gauge is adequate for the length used due to increased line set application.
10. Vibration and Noise: In long line applications, refrigerant tubing is highly prone to transmit noise and vibration to the
adjoining structure. Use adequate vibration-isolating hardware when mounting line set to structural members. See
Figures 1-1, 1-2 and 1-3 for example of proper mounting.
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