Wiktionary
thermostatically
adv. By means of a thermostat.
WordNet
thermostatically
adv. by thermostat; in a thermostatic manner; "the temperature is thermostatically controlled"
Usage examples of "thermostatically".
So, since it was economically impractical to redesign or to relocate the engine, the choice was between thermostatically heating the coils to one degree Celsius, or in making sure there was never any water in the working fluid passing through the coils.
It is a storage type, with a pilot light and a thermostatically controlled main flame.