Trane manual Motor and Drive Selection, Parallel Fan Operation, Application Considerations

Application Considerations

Table A-3 — Maximum Torque For

Operation Of InletVanes

		Control	Opening	Closing
		Arm	Torque	Torque
Size	Class	(In.)	(In.-Lb)	(In.-Lb)
	1		8	7
16	2	8.75	14	13
	3		23	22
	1		12	11
19	2	8.75	21	19
	3		34	31
	1		17	15
21	2	8.75	31	26
	3		32	44
	1		26	20
24	2	8.75	48	36
	3		79	61
	1		37	27
27	2	8.75	66	48
	3		109	79
	1		52	35
30	2	8.75	94	63

Table A-4 defines this constant system curve as a percent of wide- open cfm. If fans in parallel are always operated to the right of this constant system curve, fan paralleling will not occur.

Table A-4 — Parallel Operation

	Minimum % of WOCFM
	ForTwo Model Q Fans
Fan Size	In Parallel
16	80% WOCFM
19-21	81% WOCFM
24-30	83% WOCFM
33-44	73% WOCFM
49-60	85% WOCFM

Motor and Drive Selection

The Model Q fan has been designed for use with NEMA “T” Frame

motors. Motor hp limits for Class I, II, and III construction are listed in the roughing-in Dimensional Data section of this catalog.

Minimizing belt tension forces increases bearing life and reduces fan noise. The Q fan and Super Q II fan drive selection is totally computerized by the factory to achieve quiet, long life operation. IfTrane provides Q fan drives, all fan motor information must be made available to theTrane sales engineer.

	3		155	104
	1		65	41
33	2	8.75	128	81
	3		212	134
	1		100	59
36	2	10.81	180	106
	3		298	175
	1		138	75
40	2	10.81	249	136
	3		412	225
	1		193	99
44	2	10.81	349	179
	3		576	295

Parallel Fan Operation

The Q fan performance curve has a characteristic shape where two different cfm’s are possible at the same static pressure. Therefore, when selecting fans for multiple installation connected with either a common inlet, a common discharge or both, care must be taken to eliminate the possibility of fan paralleling.

Figure A-7 shows two typical cfm-sp performance curves for the Q fan. Fan paralleling can occur when multiple fans are selected in the shaded area.

The shaded area is determined by going straight across from the lowest point of the fan performance curve at the left of the surge line (A and A1) to the same curve to the right of the surge line (B and B1). Points B and B1 fall on a constant system curve.

Figure A-7 — Selecting Model Q Fans in Parallel

Recommended Q Fan Configuration Inside an Air Handler

Side View

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