A tempering valve is one of the best ways to ensure people are not harmed or scalded by hot water when it comes out of a faucet. It works as a mixing tool, as it combines both cold and hot water to correctly produce the required water temperature to be released from a particular outlet.Click to see full answer. Besides, how does a hot water system tempering valve work?A tempering valve is a 3-way mixing valve which is temperature actuated and used to temper a heated water supply by mixing the heated water with cold to feed heated water at a reduced temperature to the taps around your home.Furthermore, how do you adjust a water tempering valve? To adjust the mixed outlet temperature of the tempering valve the cap should be removed > to gain access to the adjusting spindle. Using the special tool moulded into the top of the cap rotate the adjusting spindle to achieve the required temperature. Correspondingly, how does a water mixing valve work? A thermostatic mixing valve (TMV) is a valve that blends hot water with cold water to ensure constant, safe shower and bath outlet temperatures, preventing scalding. They also shut off rapidly in the event of a hot or cold supply failure to prevent scalding or thermal shock.What happens when tempering valve fails?Tempering valves like any mechanical item are prone to failure. Problems with tempering valves can cause a variety of issues including complete loss of hot water supply, a lack of pressure or a reduced hot water temperature.