I like what you have done. I have a chiller that has 60 ft of copper in two coils, one inner, one outer. However, it is all one unit. What I like about your unit is its versatility. You will be able to use one or both units. And your units will clean up much, much easier than if both coils were in one unit. Adding the recirculation arm should aid considerably cooling the wort. I like what you did.