Relay vs Dimmer

A C-Bus relay is basically a controlled switch.. you can only turn things on and off with it. You would normally use a relay for controlling lights you don't really care about dimming... a closet, a pantry, the garage, or lamps types that can't be dimmed (most fluorescents). You can also use it to switch other things on and off for, for example a fountain, or a pool pump. Relay channels work out cheaper than dimmer channels, and can also switch bigger loads. This is why you'd usually use relays where you don't need a dimmer.

A C-Bus dimmer lets you control the brightness of the lights instead of just turning them on and off (although it does do that too). You can't use a dimmer for much more than lighting... it is *possible* to control the speed of a fan (ceiling or exhaust) with a dimmer channel, however this may* result in audible mechanical noise from the fan, which most people find annoying. It's a bit hit amd miss, so it's not usually recommended.

Hope this helps,

Nick

*this depends very much on the particular fan... we have ones here that are dead silent when dimmed, and others of the same make that are noisy.