The thermostat ta atomatik yana daidaita adadin ruwa yana shiga rado na ruwan sanyi don daidaita damar da aka watsewa da tabbatar da cewa injin ya shafi kewayon zazzabi. Dole ne a kiyaye sararin samaniya cikin kyakkyawan yanayin fasaha, in ba haka ba zai shafi yadda ya shafi aikin al'ada na injin. Idan an buɗe babban ɗan maraƙin mahaifa da latti, zai haifar da zafin ruwa. Idan an buɗe babban bawul ɗin ma da wuri, za a tsawaita lokacin injin injin ɗin kuma zafin jiki zai yi yawa.
Duk a cikin duka, manufar thermostat ita ce kiyaye injin da yin sanyi sosai. Misali, bayan injin yana aiki yadda yakamata, injin na iya zama mai sanyi sosai a saurin hunturu ba tare da mai zafi ba. A wannan gaba, injin yana buƙatar dakatar da yaduwar ruwa don tabbatar da cewa zafin jiki bai da ƙasa sosai
