Shower Too Hot or Too Cold? Common Shower Valve Problems

Few things are more annoying than a shower that won't stay at the right temperature. It might swing from hot to cold, never get hot enough, or turn scalding when someone flushes a toilet. The cause is usually in the shower valve or the water heater, and most of these problems are fixable without opening the wall.

How a Shower Valve Controls Temperature

Behind your shower handle is a valve that mixes hot and cold water. Inside it is a cartridge, the part that moves when you turn the handle. Most modern valves are one of two types:

• Pressure-balancing valves react when the pressure on the hot or cold side drops, like when someone flushes a toilet, and adjust the mix so you don't get a blast of hot or cold.
• Thermostatic valves hold the temperature you set more precisely. They're common in higher-end showers with several outlets.

Many older homes have valves with neither feature.

Problem: Temperature Swings When Someone Flushes

If the shower goes hot or cold whenever a toilet flushes or the dishwasher starts, either your valve doesn't have pressure balancing, or its pressure-balancing parts are worn or scaled up. In Tampa Bay's hard water, mineral scale is a common reason cartridges stop working properly. Replacing the cartridge usually fixes it. If the valve is an older type without pressure balancing, replacing the valve is the long-term fix.

Problem: Water Won't Get Hot Enough

• The anti-scald stop is set too low. Many valves have an adjustable limit, under the handle, that keeps the handle from turning all the way to hot. It's sometimes set too conservatively, and a plumber or a handy homeowner can adjust it.
• The cartridge is worn or scaled. It may not open fully to the hot side anymore.
• Every faucet is lukewarm: the problem is the water heater, not the shower. It may be undersized, set too low, or failing. See what size water heater you need.

Problem: Hot Water Runs Out Fast

If the shower starts hot and goes cold sooner than it used to, the water heater is the likely cause. Sediment from hard water takes up space in the tank, and a failing heating element on an electric heater cuts its output. See why your water heater is popping.

Problem: The Shower Is Scalding

Very hot water from the shower is a burn risk, especially for young children and older adults. Check the water heater's thermostat. Many safety organizations recommend about 120°F as a setting that's hot enough for everyday use while reducing scald risk. Then check the shower valve's anti-scald stop and make sure the pressure-balancing parts are working.

Problem: Dripping Shower Head

A shower head that keeps dripping after the water is off almost always means a worn cartridge or seal. It's the same repair that fixes many temperature problems.

Repair or Replace the Valve?

Replacing a cartridge is usually a quick repair and doesn't require opening the wall. Bring the old cartridge or the valve's brand to the store if you're doing it yourself, since cartridges are specific to each valve. Replacing the whole valve, to add pressure balancing or change to a thermostatic valve, means opening the wall behind the shower, so it's often done as part of a bathroom remodel.

Shower Trouble?

Believe Plumbing repairs and replaces shower valves and cartridges across Tampa Bay, including Tampa, Westchase and Brandon. See our tub and shower services or contact us for a free estimate.