If you know enough about electronics you could wire a buzzer up to the Ranco. Inside the ranco a Normally open and Normally closed set of contacts exist with a common point. When it is allowing voltage to pass the one set will be closed and the other open. When it reaches a given temp it will change state and the other pin will have the 120 VAC on it. Wire this to a 120 VAC buzzer and tie in the neutral with all the rest and you now have an alarm on the Ranco.