Amathuluzi okulawula izinga lokushisa, azaziwa nangokuthi ama-valve we-thermostatic, kuyisicelo esijwayelekile sama-valve okulawula ukuhamba emkhakheni wokulawula izinga lokushisa. Isimiso sawo esiyisisekelo ukuwulawula umthamo wokungena komkhiqizo opholile (noma oshisayo) ezikhumulweni zokushintshisana kokushisa, emishini yokupholisa, noma eminye imishini esebenzisa ukushisa noma ukupholisa ukuze kulawulwe izinga lokushisa lokuphuma kwemishini. Lapho umthwalo ushintsha, umthamo uyashintshwa ngokushintsha ukuvulwa kwe-valve ukuze kukhishwe imiphumela yokushintsha komthwalo futhi kubuyiselwe izinga lokushisa kwenani elibekiwe.