I've got a DIG-220, and your description sounds similar to the way my unit operates. As a word of caution, if you have a high % selected with low water temp, you could easily find the unit at 100% output as the water warms up. The unit has internal calulations to keep your Cl output constant at variable water temps.

I installed my unit in late Feb 2 years ago, and had very high CL levels for a while by doing what you're describing. I adjusted the output to a low level until the water warmed up enough to keep output stable (mid 60's?). After that happens, you'll get a better idea of where your FC level goes vs. the output on the controller.