What is a tempering valve?
Terry Smith • December 17, 2025
What is a tempering valve? www.americanplumbingla.com
What is a tempering valve?
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A tempering valve is a plumbing safety device that mixes hot water with cold water to deliver water at a controlled, safe temperature.
What it does
Reduces very hot water from a heater to a preset temperature
Prevents scalding at taps, showers, or fixtures
Keeps water temperature consistent even if pressure or supply changes
Where it’s commonly used
Domestic hot water systems (homes, apartments)
Bathrooms, showers, sinks
Solar and heat-pump water heaters (which often store water at higher temperatures)
Hospitals, schools, childcare centers (where safety standards are strict)
Why it’s important
Water heaters are often set to 60°C (140°F) or higher to prevent bacteria like Legionella
Tempering valves typically reduce outlet temperature to around 45–50°C (113–122°F), which is much safer for skin
How it works (simple)
Hot water enters the valve
Cold water enters the valve
The valve blends them to a set temperature
Mixed water exits to fixtures
Tempering valve vs thermostatic mixing valve (TMV)
Tempering valve: Usually serves an entire house or group of fixtures
TMV: More precise, often used at individual outlets (like a single shower)
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