Why do I measure full voltage output when the control says it should be less?

Why do I measure full voltage output when the control says it should be less?

The control and expansions need to have a load connected for the triac to give a correct output. If there are no mats (load) connected to the triac output, the output will always read full voltage, no matter what you set the control to. As soon as you connect mats to the triac output, the output will drop to 0%, 50% or whatever output you are manually testing at.