Sterilising hot water tank contents by regulated overheating - with auxiliary heat exchanger submerged in tank

摘要

A hot-water supply tank (1) linked to the boiler (9) of a central heating plant, esp. of domestic type, has a cold water inlet (2) and hot-water draw-off point (3). To prevent growth of harmful bacteria in the tank (1), the tank holds an auxiliary heat exchanger (4) which under the control of a timer etc. (17) heats the tank contents to an elevated temp. at which any bacteria are necessarily killed, over a max period of about 15 mins.. The heating is pref. at a time, e.g. before dawn, when hot water usage is minimal, and power is at cheap rate. After treatment, the heated supply is allowed to return to normal operating temp. for transfer to the main supply circuit via multi-way valves (15) controlling a pair of circulation pumps (14,16). ADVANTAGE - Extra power consumption in safeguarding hot water supply, e.g. from Legionaires disease, is minimum.