Greenheck Fan 240XP-CUb manual Matching a Specification, Model RSF and BCF Selection

Matching a Specification

There will be times when a Greenheck model will have to be matched to a competing manufacturer’s unit. To aid in these circumstances, we have provided a cross reference chart which includes our nine most common competitors. If the manufacturer you need is not on this chart, contact Greenheck for assistance.

To use the cross reference chart, on next page, start with the manufacturer at the top. Then follow down until the model in question is found. Follow across to

the left to determine which Greenheck model is equivalent. Once this is determined, refer to the Greenheck catalog to find the best size to meet the specified performance.

Hint: Typically, when matching a Greenheck fan to a competitive model, the size should also be matched. If you are unsure of the size of the competitive unit, compare fan rpm. Fans of equal size should move approximately the same amount of air.

Model RSF and BCF Selection

The RSF and BCF selection charts are different from all other selection charts. For these models, the cfm values are at the left side of the chart in a single column and the rpms are in the performance boxes. It is just the opposite for other models. The reason for this is that the RSF and BCF models are forward curved, and the fan industry historically catalogs forward curved fans in this fashion.

Sample problem:

Choose the fan size and appropriate motor horsepower to move 980 cfm against 0.625 in. Ps.

Solution: (Refer to table below)

The first row in the chart corresponds to 980 cfm. Follow across to the right to the 0.625 in. Ps column. The performance box reveals that size 90 will meet this performance at 893 rpm and will require 0.20 Bhp.

Motor hp selection for forward curved fans is more

complicated. The Bhp is only 0.20, which suggests that a 1/4 hp motor is adequate. However, forward curved fans draw more horsepower at low Ps than at high Ps. Assume this fan was running at about 893 rpm, but instead of 0.625 in. Ps, it was operating at only 0.25 in. Ps. The new performance box in the 0.25 in. Ps column reveals 894 rpm at 0.45 Bhp. The airflow would then be 1860 cfm.

Notice that as the Ps was reduced from 0.625 in. to 0.25 in., the Bhp increased from 0.20 to 0.45. This would burn out the 1/4 hp motor quickly. With this in mind, it is good practice to size RSF and BCF motors at least one size larger than necessary based on the Bhp value in the performance box, especially if the estimated Ps is questionable.

For this case, an RSF-90-3 (1/3 hp motor) would be a good selection if we had confidence in the estimated Ps. Otherwise, use an RSF-90-5 (1/2 hp motor).

RSF-90-4 (1/4 hp motor) is not recommended for this job.

	CFM	OV					STATIC PRESSURE / CAPACITY
MODEL
				0.125	0.250	0.375	0.500	0.625	0.750	1.000	1.250	1.500	1.750
	980	1065	rpm	521	630	725	812	893	967
			Bhp	0.08	0.11	0.13	0.16	0.20	0.23
	1200	1304	rpm	593	685	771	849	925	994	1125
			Bhp	0.13	0.16	0.19	0.23	0.26	0.30	0.38
	1420	1543	rpm	668	747	825	898	966	1031	1153	1267	1371
RSF-90			Bhp	0.19	0.23	0.27	0.31	0.35	0.39	0.48	0.57	0.67
	1640	1783	rpm	746	819	887	953	1016	1077	1191	1298
			Bhp	0.28	0.33	0.37	0.42	0.46	0.51	0.61	0.71
	1860	2022	rpm	828	894	954	1014	1073	1128	1236
			Bhp	0.40	0.45	0.50	0.55	0.60	0.65	0.76
	2080	2261	rpm	910	970	1027	1080	1134
			Bhp	0.54	0.60	0.66	0.71	0.77
	1240	1097	rpm	476	572	656	733	807	876
			Bhp	0.10	0.13	0.16	0.19	0.23	0.27
RSF-100	1780	1575	rpm	605	679	748	813	873	931	1040	1143	1240
			Bhp	0.24	0.29	0.33	0.38	0.42	0.47	0.56	0.66	0.77
	2140	1894	rpm	699	763	823	880	935	989	1086	1181	1269	1354
			Bhp	0.40	0.45	0.50	0.56	0.61	0.67	0.78	0.89	1.00	1.12

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