On mine (not a NuTone) the hose has a metal ring on it that shorts
across two little contacts in the wall box to turn the machine on. I
think the control voltage is 24volt, same as an a/c. It has a relay
inside the unit that sends the line voltage to the motor. Mine is 230
volt-- plenty powerful! Have you tried any troubleshooing on this unit
yet? If the unit is indeed bad, I would imagine it could be replaced
with any other brand. Holler if you got any questions-- I installed mine
myself:there really isn't that much to one. Larry