The clean tube temperature factor is the manufacturer's version of U. Given the inlet flow conditions and the desired output, they provide you a number to select the product you need. They probably just don't want to reveal more information about the construction of their products than what is...
Watch the direction of your inequality signs, but even still, you aren't going to get much useful information out of this equation. Important heat transfer properties of the exchanger and both flows are not considered.
U is used to find q, not the other way around.
Table A: The clean tube temperature factor appears to be their own internal product selection convention, done for the sake of the customer. Taking into consideration required water flow rate, water temp in, water temp out, and steam pressure.
The 2nd table gives the overall pressure drop (in...
