Lennox International Inc 15CHAX Series Unit Start−Up and Operation, Pre−Start Check List

Unit Start−Up and Operation

Each 15CHAX packaged cooling unit is factory−charged with R−410A refrigerant. The compressor is hermetically sealed, internally sprung and base−mounted with rubber−insulated hold−down bolts.

Pre−Start Check List:

1 − Make sure refrigerant lines do not rub against the cabi- net or each other.

2 − Inspect all electrical wiring, both factory− and field− installed, for loose connections.

3 − Check voltage at the disconnect switch. Voltage must be within the range listed on the unit nameplate. If not, consult power company and have voltage condition corrected before starting unit.

4 − Recheck voltage with unit running. If power is not with- in the range listed on the unit nameplate, stop the unit and consult the power company. Check unit amper- age. Refer to unit nameplate for correct running amps.

5 − Make sure filter is in place before unit start−up.

6 − Before placing the unit into full operation, energize the unit for three false starts. Energize the compressor just long enough for it to make a few revolutions, wait five to seven minutes before repeating a second and third time.

Cooling Sequence of Operation

When the thermostat calls for cooling, the

is closed to energize the compressor contactor. The contactor brings on both the compressor and outdoor fan. The thermostat also closes the

the circulating air blower. When the cooling demand is satisfied, the thermostat opens the circuits, as well as the compressor contactor. The compressor and outdoor fan

immediately stop. The circulating air blower continues operating through a 90−second delay.

Unit compressors have internal protection. If there is an abnormal rise in the compressor temperature, the protector will open and the compressor will stop.

System Performance

For maximum performance of this cooling system, the operating temperatures and pressure should be checked and subcooling determined at Standard ARI test conditions of 82_ F outdoor temperature / 80_ F indoor dry bulb / 67_ F indoor wet bulb. If subcooling measured deviates from values in table 6, refrigerant charge should be adjusted accordingly for maximum performance.

Table 6

Suction Superheat Values

	Suction Superheat
Unit Model No.	82_F OD / 80_F IDDB
	/ 67_F IDWB
15CHAX−24	12_
15CHAX−30
15CHAX−36	15_
15CHAX−42
15CHAX−48	10_
15CHAX−60

Verify system performance using table 7 as a general guide. Table 7 should not be used for charging unit. Minor variations in these pressures may be expected due to dif- ferences in installations. Significant differences could mean that the system is not properly charged or that a prob- lem exists with some component in the system.

Used carefully, this table could serve as a useful service guide. Data is based on 80°F dry bulb / 67°F wet bulb return air. Allow unit operation to stabilize before taking pressure readings.

Table 7

Normal Operating Pressures

80°F db / 67°F wb RETURN AIR					Air Temperature Entering Outdoor Coil (°F)
UNIT	PRESSURE	65	70	75	80	82	85	90	95	100	105	110	115
15CHAX−24		142	143	144	146	146	147	148	149	150	151	152	153
15CHAX−30		134	136	138	140	141	142	144	146	148	149	151	152
15CHAX−36	Suction	143	144	146	147	148	149	151	152	155	155	157	157
15CHAX−42		140	140	140	141	141	141	142	142	143	144	145	147
15CHAX−48		140	141	142	144	144	145	146	147	148	149	150	151
15CHAX−60		143	144	145	146	146	147	147	148	149	150	151	152
15CHAX−24		219	242	264	287	296	310	333	355	379	398	430	457
15CHAX−30		232	255	277	300	309	323	345	368	390	408	440	470
15CHAX−36	Liquid	244	268	292	316	326	340	363	369	410	429	461	493
15CHAX−42		225	247	269	291	300	314	337	357	383	402	434	457
15CHAX−48		243	264	285	307	315	328	349	370	391	408	440	470
15CHAX−60		257	280	303	326	335	349	372	395	418	436	468	497

Page 13