Why Does My Home’s Water Temperature Keep Changing?

One moment it’s hot, then the next it’s cold — why can’t the water temperature be just right? As plumbers, we know how frustrating it is to deal with fluctuating water temperatures in your home. Drastic temperature changes can even be dangerous, especially if your water suddenly gets hot without warning.

Getting to the bottom of this issue will require a bit of troubleshooting. Walking through the steps below will help you determine what’s causing the water temperature fluctuation in your home.

If you need water heater services in New Orleans or Metairie, contact Stuart Services to get started.

1. The Water in My Home Gets Hot Suddenly

If the water in your home gets hot suddenly, try to notice when this happens. Typically, this problem happens in the shower in an older home when someone flushes the toilet or turns on the bathroom faucet.

Why does this happen?

Frequently in older homes, all the plumbing fixtures in one bathroom share the same central cold water line and hot water line. When you shower, you likely use water from the cold line and the hot line so that what comes out is warm but not scalding.

When someone turns on the faucet or flushes the toilet, suddenly, a bunch of cold water pressure is taken away from your shower, and you’re left with a lot of undiluted hot water — ouch!

What should I do about it? 

Eventually, you can add more water lines when you get your home repiped. However, if you’re not ready to repipe, have a plumber install a thermostatic mixing valve in your shower. This device will prevent you from getting scalded when there’s a drop in cold water pressure.

2. The Water in My Home Gets Cold Suddenly

If your water goes from hot to cold then hot again, or from cold to hot then cold again, skip to Step 3. If your water starts out hot and then gets cold, you most likely have a water heater issue.

Why does this happen?

Routinely running out of hot water most likely means one of two things: Either your water heater is failing or it isn’t big enough for your household. Tank water heaters last about 10 years on average, while tankless models last 20 years or more.

If your water heater isn’t old and you’re running out of hot water, then you may need to invest in a larger-capacity model. If you own a tank model, it’s possible that the tank size isn’t large enough to store all the hot water your household needs.

If you own a tankless model, you might be using too many hot water sources at once, overstretching the unit’s max flow rate (gallon per minute).

What should I do about it?

If your water heater is 10 years or older, then replacing it will likely resolve the issue. However, it’s best to get a plumber’s professional opinion first. If your water heater isn’t that old and you don’t want to replace it with something with a higher capacity, you can try installing faucets and showerheads with low-flow rates.

That way, each shower your family takes will use less hot water. If you own a tankless model, you can also try to avoid using hot water in too many places simultaneously.

3. The Water in My Home Changes Between Hot & Cold Inconsistently

If your water goes from hot to cold then hot again, or from cold to hot then cold again, you likely have a problem with a thermostatic mixing valve in one of your plumbing fixtures (like your shower or one of your faucets).

Thermostatic mixing valves are supposed to keep your water temperature consistent by detecting drops in hot and cold water pressure. When they stop working, you can experience extremely hot and cold water temperatures without even touching your faucet handles.

Why does this happen?

Just like any device, thermostatic mixing valves get wear and tear after years of usage.

What should I do about it? 

Unless you’re a professional plumber, we don’t recommend repairing or replacing a thermostatic mixing valve yourself. This device needs to function correctly to prevent you from getting scalded. It’s safer to let a trained plumber replace this part.

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Get Reliable Water Heater Solutions With Stuart Services

Fluctuating water temperature in your home can be frustrating, but it’s often a sign that your water heater needs professional attention. At Stuart Services, we specialize in diagnosing and resolving water heater issues to restore your comfort and peace of mind. Whether it’s a minor repair or total replacement, our experienced team can help.

Don’t let inconsistent water temperatures disrupt your daily routine. Contact Stuart Services to schedule your water heater service, and let us ensure your home’s hot water system is running smoothly and efficiently.

Need a hand with your home’s plumbing? Trust the New Orleans home experts at Stuart Services. Call today to schedule your service.