Amathuluzi okulawula izinga lokushisa, azaziwa nangokuthi ama-valve e-thermostatic, kuyisicelo esijwayelekile sama-valve okulawula ukuhamba emkhakheni wokulawula izinga lokushisa. Umgomo wabo oyisisekelo uwukulawula isivinini sokungena somphakathi opholile (noma oshisayo) emashalofini okushisa, kumayunithi wokupholisa, noma kwezinye izinsiza ezisebenzisa ukushisa noma ukupholisa ukuze kulawulwe izinga lokushisa lokuphuma kwensiza. Lapho umthwalo ushintsha, isivinini sokuhamba silungiswa ngokushintsha ukuvulwa kwe-valve ukuze kususwe imiphumela yokushintsha komthwalo futhi kubuyiselwe izinga lokushisa kwinani elibekiwe.