I know it's probably more expensive but is there any reason not to use an Auber Sous Vide temp controller for a rims system?http://www.auberins.com/index.php?main_page=product_info&products_id=44
Looks like a good option for controlling up to 15a @ 120v. You will probably need a different temp sensor for mounting in the rims tube.
Ask auberins which sensors are compatible.
Digging up an old thread. Did you purchased the built controller for your rims tube?