Dear Oly77,
At best your posted question is vague. You seem to have an air handler system, your measured volts at A, B, and C are 268, 270, and 270 respectfully, your measured amps at A, B, and C are 7, 7, and 8 amps respectfully, and your delta T is 25 degrees F (educated guess). You now what to know what your CFM is.
IF you have a resistance heater, and IF the amps on the heater ONLY are the measured 7, 7, and 8, and the heater has a heat rise of 25 degrees F, then:
CFM = BTU/Hr / 1.08 x TD
CFM = (7 + 7 + 8) x (268 + 270 + 270) x 1.73 x 3.41 / 1.08 x 25
3 3
CFM = 7.333 x 269.3 x 1.73 x 3.41 / 1.08 x 25
CFM = 11,649 BTU/Hr. / 27
CFM = 431.4
IF on the other hand, ANY of the above prerequisites are not correct, then the above CFM calculation is not correct.
Hope this helps ..and next time please be a bit more clear as to what the readings are.
Respectfully Submitted,
John J. Dalton CM