I just bought a Montigo L38DF gas fireplace with the optional fan kit. The wiring diagram is very unclear as to how to install this unit. Here's my interpretation: The diagram shows 120v coming into a 120v/24v transformer (and also into an outlet box where the fan kit plugs in to). The transformer then has three low voltage wires coming from it to the millivolt gas valve. One of the wires passes through a wall switch first. Does this make sense? Also, the kit did not come with the transformer. Is it typical to have to buy that separately?