Cov raj tooj dag yog lub teeb hauv qhov hnyav, muaj cov thermal conductivity zoo, thiab lub zog siab kub qis. Lawv feem ntau siv los tsim cov khoom siv hluav taws xob sib pauv (xws li condensers, thiab lwm yam). Lawv kuj tseem siv los sib sau cov kav dej kub qis hauv cov khoom siv oxygen. Cov raj tooj liab uas muaj cov kab me me feem ntau yog siv los thauj cov kua uas muaj zog (xws li lub tshuab lubrication, roj siab tshuab, thiab lwm yam) thiab ua cov ntsuas ntsuas siab rau cov twj paj nruag. Brass tubes muaj zog thiab corrosion-resistant.
Lawv feem ntau muaj qhov zoo hauv qab no: cov raj tooj liab yog qhov nyuaj, tsis yooj yim rau corrode, thiab tiv taus qhov kub thiab txias siab, thiab tuaj yeem siv rau ntau qhov chaw uas tsis yog tooj liab. Piv nrog rau tooj dag raj, ntau lwm cov kav dej muaj qhov tsis zoo. Piv txwv li, cov kav dej galvanized steel, uas tau siv ntau dua hauv cov tsev nyob yav dhau los, yooj yim heev rau xeb. Tom qab siv sijhawm luv luv, kais dej yuav tig daj thiab dej ntws yuav txo qis. Kuj tseem muaj qee cov ntaub ntawv uas nws lub zog yuav txo qis ntawm qhov kub thiab txias, uas yuav ua rau muaj kev pheej hmoo tsis zoo thaum siv cov kav dej kub. Txawm li cas los xij, vim qhov kub ntawm qhov kub ntawm cov tooj liab, qhov kub ntawm cov dej kub muaj qhov cuam tshuam me ntsis rau cov raj tooj dag. Cov khoom siv tooj dag muaj xws li tooj dag raj rau cov khoom siv hluav taws xob, tooj dag raj rau cov tub yees, cov khoom siv hluav taws xob muaj zog tiv taus tooj dag, cov hlau tsis xeb corrosion-resistant, tooj liab tubes rau kev sib txuas, tooj liab raj rau cov dej, hluav taws xob cua sov tooj dag raj, thiab cov raj tooj dag muaj.
