Amathuluzi okulawula izinga lokushisa, azaziwa nangokuthi ama-valve thermostatic, iyisicelo esijwayelekile sama-valve okulawula ukuhamba emkhakheni wokulawula izinga lokushisa. Umqondo wabo oyisisekelo uwukulawula isivinini sokungena somkhiqizo opholile (noma oshisayo) ezikhumulweni zokushintshisana kokushisa, kumayunithi wokushisa, noma kwezinye izinsiza ezisebenzisa ukushisa noma ukupholisa ukuze kulawulwe izinga lokushisa lokuphuma kwezinsiza. Lapho umthwalo ushintsha, isivinini sokuhamba silungiswa ngokushintsha ukuvulwa kwe-valve ukuze kususwe imiphumela yokushintsha komthwalo futhi kubuyiselwe izinga lokushisa kwenani elibekiwe.