Power to switch Then four wires + ground to unit. One wire is neutral. Each of the other three wires is power to fan, heater, light.
At switch connect power neutral to unit neutral.
Connect power to three pigtails. Connect one pigtail to each switch. Connect hot wires fro unit to each separate switch.
You are most likely going to need #12 for the heater, and that would most likely have to be on a separate circuit than the lights. Post the spec's on the unit, which is manufacturer & model #, and pictures of your current switch layout.
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