Gary,
I am looking at absolutely no heat exchanger, for the absolute minimal maintenance.
also I am in Dallas TX, so even during the coldest day here last year my attic was warm. Any snow we have here (rare in and of itself) will be melted off of the roof by noon.
I may at some later time seek to utelise the dryer's exhaust air for some purpose, but not initially.
I am only looking to increase the dryer's intake air to minimalize the time that the heating elements turn on. I may be forced to create a logic circuit for this purpose sop that the dryer can be used as normal (or retrain the wife to use the "tumble dry" setting during the daytime and early evening. It would be much easier to create and install a simple logic circuit activated by intake air temp)
If I have any time this weekend, I will pull the covers off of the dryer to see about making/installing an intake manifold.
Rob