Tekmar tN4 User Switch - Preprogrammed. tekmarNet??4 User Switch 479 is a simple 3 button switch that provides an easy way to override system temperatures. This user switch is a must have for any tekmarNet??system. Using tekmarNet??4 to communicate with any or compatible tekmarNet??devices, 479 User Switch allows owner to override ir entire tekmarNet?system, and offers potential for significant energy savings. With push of a button, user can place all rmostats and boiler controls into an away" state and take advantage of saving energy when building is not being used.