They are much less efficient in relation to the water because of the 20 times lower rate of heat transfer through the air with respect to water, with the result that the energy source is a low-temperature heating .
Wao ni kidogo sana ufanisi katika uhusiano na maji kwa sababu ya kiwango cha chini mara 20 ya uhamisho joto kwa njia ya hewa kwa heshima na maji, na matokeo ya kuwa chanzo cha nishati ni ya chini – joto inapokanzwa .