Carrier 90MA/MF/MU manual Unit Length of RUN

Table 4 Recommended Line Sizes, Remote Condenser

UNIT				LENGTH OF RUN
(90MU)
	0--25		26--50		51--75		76--100
	DISCH	LIQUID	DISCH	LIQUID	DISCH	LIQUID	DISCH	LIQUID
004	1/2 (1.3)	1/2(1.3)	5/8(1.6)	1/2(1.3)	5/8(1.6)	1/2(1.3)	7/8(2.2)	1/2(1.3)
006	5/8(1.6)	1/2(1.3)	7/8(2.2)	1/2(1.3)	7/8(2.2)	1/2(1.3)	7/8(2.2)	1/2(1.3)
008	7/8(2.2)	5/8(1.6)	7/8(2.2)	5/8(1.6)	7/8(2.2)	5/8(1.6)	1-1/8(2.9)	5/8(1.6)
012	7/8(2.2)	5/8(1.6)	1-1/8(2.9)	5/8(1.6)	1-1/8(2.9)	5/8(1.6)	1-1/8(2.9)	5/8(1.6)

NOTES:

1.Line sizes given in inches (cm).

2.Line sizes should never be smaller than cooling unit connection size.

3.A nominal number of fittings has been considered in determining line sizes. Smaller line sizes may be considered if run is simple and few fittings are used.

d. Hold flare tightly against fitting while connecting flare nut. Round end of cotter pin will depress core of fitting. The opened fitting allows refrigerant pressure to act on water regulating valve. Tighten nut to pre- vent leakage. Fitting automatically seals when nut is removed.

REMOTE MOUNTED CONDENSER (90MU) - Install

remote mounted condenser in accordance with the installation instructions provided with condenser. Connection locations for liquid and discharge lines are shown in Figure 5. Recommended line sizes are given in Table 4. Additional instructions can be found in Carrier System Design Manual, Part 3, for standard refrigeration piping techniques. On 008 and 012 size units, secure discharge line to bracket at unit outlet using proper clamp from supplied fastener package

Condenserless (90MU) units are shipped with a refrigerant holding charge. After refrigerant connections are made, leak test, reclaim refrigerant, evacuate, and charge system as described in paragraph 5.9.

3.13Install Condensate Drain Line

Install a trapped condensate drain line at unit drain connection. The drain requires standard pipe connected to condensate pan nipple(s). Figure 7 shows proper trap design.

Determine design negative static pressure. This pressure is not the same as fan total static pressure, which includes pressure losses downstream as well as upstream from the evaporator air fan. Always assume the worst conditions, such as having return air filters clogged with debris.

Referring to Figure 7, differential 1 must be equal to or larger than negative static pressure at design operating condition. Store enough water in trap to prevent losing seal. Differential 2 must be equal to or larger than one-half the maximum negative static pressure. To avoid loss of seal when the fan starts, differential 3 must be greater than the maximum negative static pressure.

Figure 7 Condensate Drain Trap

Do not use drain line smaller than 3/4 inch. Use hole(s) provided in panel for drain line. Pitch drain line downward toward scupper. Installation of a plugged tee is recommended for cleaning. Fill trap with water to make an air seal. Observe all sanitary requirements.

3.14Make Electrical Connections

GENERAL - Provide an adequate fused disconnect switch within sight of the unit. Provision for locking switch open (OFF) is advisable to prevent power from being turned on when unit is being serviced.

POWER WIRING - Conduit opening for all units is on left side of unit near control box. Connect field power wires at the compressor contactor.

Supply voltage must be in accordance with nameplate voltage. Voltage between phases must be balanced within 2% and current within 10% with compressor running. Correct improper voltage or phase imbalance. Unit failure as a result of operation on improper line voltage or excessive phase imbalance constitutes abuse and shall void the Carrier warranty. Use the following formula to determine the percent voltage imbalance.

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