The potable water flow rate used in Soto de Ribera is Qr = 70m3/h pr 0.0194 m3/s.During the coldest months,the water temperature could be even lower than that of the river water (Fig.4).Thus,T1=7 ํC is chosen as lowest reference water temperature.This water has to be heated up to t2 =18 ํC. Taking into account that the hot water temperature is T1 = 35 ํC
and it decreases to T2 = 18 ํC,the maximum necessary hot water flow Qt can be determinded: