Replace Shower Mixing Valve

mixing valve
A Thermostatic Mixing Valve (TMV) is a valve that blends hot water (stored at temperatures high enough to kill bacteria) with cold water to ensure constant, safe outlet temperatures preventing scalding.
A valve that mixes hot and cold water in the valve to obtain a set temperature prior to delivery.
A valve operated by a thermostat that can be installed in solar water heating systems to mix cold water with water from the collector loop to maintain a safe water temperature.

replace
Take the place of
Provide or find a substitute for (something that is broken, old, or inoperative)
put something back where it belongs; "replace the book on the shelf after you have finished reading it"; "please put the clean dishes back in the cabinet when you have washed them"
Fill the role of (someone or something) with a substitute
substitute a person or thing for (another that is broken or inefficient or lost or no longer working or yielding what is expected); "He replaced the old razor blade"; "We need to replace the secretary that left a month ago"; "the insurance will replace the lost income"; "This antique vase can
supplant: take the place or move into the position of; "Smith replaced Miller as CEO after Miller left"; "the computer has supplanted the slide rule"; "Mary replaced Susan as the team's captain and the highest-ranked player in the school"

shower
a plumbing fixture that sprays water over you; "they installed a shower in the bathroom"
A mass of small things falling or moving at the same time
A large number of things happening or given to someone at the same time
A brief and usually light fall of rain, hail, sleet, or snow
spray or sprinkle with; "The guests showered rice on the couple"
lavish: expend profusely; also used with abstract nouns; "He was showered with praise"