To heck with it, I didn't need to reply. You guys had covered the bases.
One thing that Sean might not have clear, though. Relays are essentially handy switches that can control voltages other than the switch that the person touches is rated for. A picture may help:
A while back, a member was looking to have a 120V pump come on whenever a low voltage thermostat "closed", or turned on.
If you trace your finger along the circuit paths, you will see how either thermostat in the system, operating at a tiny 24 Volts AC on tiny 18 gauge wire, can be made to control a 120V or 240V or 277V or 480V load, potentially on very large wire.
You see, the only load on the thermostat itself is the little coil in the relay. The coil causes the contacts to close, and in turn completes the controlled circuits.
In the case of the Ansul system, relays are used to do many tasks when only one switch closes.