Izilawuli zokulawula izinga lokushisa kanye nama-valve okulawula izinga lokushisa (ngezinye izikhathi okubizwa ngokuthi i-TCV) aklanyelwe ukulawula izinga lokushisa lenqubo ngokulawula ukucindezela koketshezi olushisayo noma ukugeleza kuma-compressor, amabhantshi amathangi, amakhoyili okushisa, noma ezinye izinto zokushisisa.