DmikeM
I think that before you tossed your alternator you should check the relays for your heater circuit. I do not have my manual on me, but the alternator would not cause the problem you are having. But a simple dvom test on the battery would let you know if the alternator was charging. The first place I would look would be a fuse or a relay. Some relays have a fusible link that is suppling power to be swithced in the circuit.
Good Luck
copter steve