Pressure-Balancing / Mixing Valve
A mixing valve blends hot and cold water to a set temperature, and the pressure-balancing version protects a shower from scalding when water is drawn elsewhere in the house.
A mixing valve is the heart of a shower or tub control, the body inside the wall that combines hot and cold into the temperature you feel. A pressure-balancing valve, the most common type in newer showers, watches the relative pressure of the hot and cold supplies and adjusts instantly to keep the mix steady. That is what stops the sudden scald or cold shock when someone flushes a toilet or starts the dishwasher and steals cold water away from the shower.
A close cousin, the thermostatic mixing valve, holds a chosen temperature directly rather than just balancing pressure, and a separate version sits at the water heater to temper very hot tank water down to a safe delivery temperature. Homeowners usually meet these valves when a shower swings hot and cold, will not reach the right temperature, or needs the cartridge inside replaced.
Because the valve body lives behind the wall, getting at it ranges from easy, through an access panel, to involved, cutting into tile from the front. Many repairs only need the cartridge inside the valve rather than the valve body itself, which keeps the simpler fixes affordable.
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- Wax Ring : A wax ring is the soft sealing gasket that sits between a toilet base and the floor flange, blocking water and sewer gas from escaping at the connection.
- Toilet Flange / Closet Flange : A toilet flange, or closet flange, is the ring that anchors a toilet to the floor and connects it to the drain pipe below, holding the bolts that clamp the bowl down.
- Fill Valve (Ballcock) : A fill valve, the modern replacement for the old ballcock, is the tank part that refills a toilet after a flush and shuts off when the water reaches the set level.
- Flapper : A flapper is the hinged rubber seal at the bottom of a toilet tank that lifts to release water into the bowl on a flush, then drops back to hold the tank full.