Hi Tyler,
Is there any chance somebody has made a dodgey alteration to the hot supply to the laundry and bathroom. If somebody has fitted a gal fitting in there (big no no on the hot water) this could be the cause of the problem, it is unlikely to be the Dux but anything is possible. A way you could test it is to disconnect the hot coming out of the unit and connect a hose to it and then turn the taps on and if you still get the rusty water coming out you know there is a problem in the pipes and not the unit
