add a flex fan or desert fan, i do not recall the proper term. ron On Wed, Nov 12, 2008 at 2:52 PM, Ed Townley <healeymonster at fastwave.biz> wrote: > Dan-- Ditto to what Ron and Don said--I have no experience with > aluminum, but had an extra core added to the sto p top and bottom > tanks--works great! last summer in sunny and HOT Southern NM,