Carrier Comprehensive Guide on Double Suction Riser and Refrigerant Piping

Step 3 — Make Refrigerant Piping

Connections

CAUTION

Do NOT bury refrigerant piping underground. Failure to comply could result in equipment damage.

The units have large suction lines to minimize friction loss- es. The units also have the ability to operate at low capacity. Because of these capabilities, use special care with suction pip- ing and suction risers to ensure proper compressor oil return under all operating conditions. If the evaporator is above the condensing unit, the maximum allowable vertical separation between the condensing unit and the evaporator is 75 ft (22.9 m) for all units. Size suction lines in accordance with Table 7 and Fig. 12.

SIZE REFRIGERANT LINES — Consider the length of pip- ing required between the condensing unit and indoor unit (evaporator), the amount of liquid lift, and compressor oil re- turn. Suction and liquid lines should be sized in accordance with Table 7. Double suction risers may be required if con- densing unit is located above the evaporator to assure proper oil return at minimum load operating conditions. See Table 7 and Fig. 12. Note the indoor unit installtion instructions for ad- ditional information.

CAUTION

The field-supplied liquid line solenoid valve must be installed at the evaporator to avoid possible compressor damage during unit operation if the maximum allowable evaporator size is exceeded per Table 8. See Fig. 13 (for 38APD025-100 dual-circuit units), or Fig. 14 (for 38APS025-050 single-circuit units).

a38-7132

LEGEND

A— Pipe A, Suction Riser, without Trap

B— Pipe B, Suction Riser with Trap

C— Suction Line to Condensing Unit

D— Pipe D, Suction Riser Short Lift RED. — Reducer

STR — Street

NOTES:

1.Short riser, pipe D, is used when routing suction line to condensing unit connection. See table at right.

2.See Table 7 for values of A, B, and C.

38AP			D PIPE DIAMETER
		Dual Circuit
UNIT					Single Circuit
SIZE	Circuit A		Circuit B
	in.	mm	in.	mm	in.	mm
025	11/8	29	11/8	29	13/8	35
027	11/8	29	11/8	29	13/8	35
030	11/8	29	11/8	29	13/8	35
040	13/8	35	11/8	29	15/8	41
050	13/8	35	13/8	35	15/8	41
060	13/8	35	15/8	41	—	—
070	15/8	41	15/8	41	—	—
080	15/8	41	15/8	41	—	—
090	15/8	41	15/8	41	—	—
100	15/8	41	15/8	41	—	—

Fig. 12 — Double Suction Riser Construction

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