Heat trace system for heating vessels of a piping system comprises a main control system, a plurality of heat trace elements, and a plurality of wireless modules. Each heat trace element is adjacent to one of the vessels of the piping system and connected to an electrical power source of the main control system 16. Each of the wireless modules: (a) is connected to and powered by an associated heat trace element; (b) comprises an energy storage device connected to the associated heat trace element for storing energy from the associated heat trace element to power the wireless module; and (c) comprises an RF module for communicating wirelessly with the main control system via a wireless communication network. The stored energy in the energy storage device can be used to power components of the wireless module, even when no current is flowing in the heat trace element to which the wireless module is connected.