why is my hot water boiling hot

Why is My Hot Water Boiling Hot

Have you noticed your hot water is suddenly scalding hot? Has your water heater started overheating, making the hot water in your home dangerously and painfullly hot all of a sudden? This article will cover the common reasons why your hot water is suddenly way too hot and what you can do to fix the issue.

When you turn on the hot water tap or step into the shower and the water is suddenly boiling hot, it can be a painful and hazardous surprise.

This article will look at the most frequent causes of hot water that’s suddenly scalding hot coming from your home’s taps and showers. We’ll also provide troubleshooting tips you can follow to get your water heater safely back to making properly heated hot water again.

What Causes Hot Water to Suddenly be Too Hot?

There are a few possible reasons why the hot water in your home may be dangerously and excessively hotter all of a sudden:

  • The water heater thermostat is broken or malfunctioning
  • One of the electric water heater heating elements has failed
  • Sediment or hard water build-up inside your water heater tank
  • The hot water temperature setting was accidentally turned up too high

Let’s examine each of these common issues in more detail to understand what can cause hot water to be painfully hot.

Water Heater Thermostat is Defective

All residential water heaters have a thermostat that controls the temperature of the hot water. Most heaters are set from 120°F to 140°F.

If the thermostat in your electric, gas or tankless water heater is defective or broken, the water heater can overheat. This will make the hot water coming out of your faucets excessively and dangerously hot.

A faulty thermostat that gets stuck in the “on” position will keep heating the water past the normal temperature setting. A broken water heater thermostat is a serious issue that should be immediately repaired to prevent safety risks.

Faulty Electric Water Heater Heating Element

Inside electric water heaters are electric heating elements that heat up the water. If one of the heating elements fails, it can lead to uneven heating of water in the tank.

A damaged heating element that is still partially working may overheat just the water at the bottom of the tank to extreme temperatures above 150°F. This scalding hot water then mixes with the rest of the water in the tank, causing painful hot spots when you use a faucet or shower.

Replacing the faulty electric water heater element is typically an easy fix. But the water heater should not be used until that defective element is replaced.

Sediment and Hard Water Build-Up

Over many years of use, sediment particles and hard water deposits can accumulate at the bottom of your hot water heater tank. This build-up acts as insulation between the water and the heating elements or burners.

That forces the heating elements or gas burners to work much harder to heat the water. This can lead them to overheat the water past safe levels above 140°F and cause excessively hot water to come out of the taps.

Draining and flushing a water heater once a year helps clear out sediment and scale-forming hard water. If it’s been more than a year since your last flush, draining the tank completely may restore proper and safe operation.

Hot Water Temperature Accidentally Set Too High

On an electric water heater, check the temperature dial on the thermostat and make sure it hasn’t been turned up too high by accident.

Gas water heaters don’t have an adjustable thermostat, but a technician may have set it too high during maintenance.

Consult your water heater manual to make sure the temperature setting hasn’t been adjusted past the recommended safe range of 120°F to 140°F maximum. Turn it down immediately if it’s been set higher than 140°F.

Steps to Troubleshoot and Fix Overly Hot Water

Once you know the common causes of suddenly too hot water, here are tips on troubleshooting the issue in your home:

Check Water Temperatures at All Faucets

Start by testing the hot water temperature at every faucet and showerhead in the home. Check sinks, tubs and laundry connections.

This helps determine if it’s a whole-house overheating issue or an isolated problem in one hot water line. It can also identify hot spots caused by specific fixtures.

Use a Thermometer to Measure Hot Water

Use a cooking thermometer or infrared thermometer to check the exact temperature of the hot water coming out of your faucets and showers.

Water above 125°F can cause serious burns fast. If the water is 140°F or hotter, shut off the water heater immediately until it can be serviced and repaired.

Check All Fixtures on Maximum Hot Setting

Turn on all the hot water taps and fixtures to the fully hot position. See if the initial burst of excessively hot water cools down after a few minutes.

If the hot water cools down after an initial spike, it points to the water heater overheating at the bottom from sediment or a stuck heating element. The hottest water at the bottom will eventually mix with the rest.

Listen and Look for Problems

Be alert for any new sounds coming from your water heater like rumbling, cracking or popping noises. Also check for leaks around the tank, valves and fittings which can signal a serious issue like a ruptured tank.

Call a Technician for Major Issues

If there are leaks or clear signs of other severe problems, shut off the water heater immediately and call a qualified appliance repair technician.

Minor fixes like replacing heating elements or servicing thermostats can often be DIY. But it’s best and safest to have a professional assess any overheating issues or safety hazards.

Drain and Flush the Water Heater Tank

If your water heater is more than a year old and hasn’t been flushed, or there are signs of sediment build-up, try draining the entire tank and flushing it thoroughly.

Make sure to turn off power to an electric water heater first. Refill the tank after flushing and test the hot water temperature. If flushing improves overheating issues, continue doing it annually.

Replace Faulty Thermostats or Heating Elements

For an electric water heater overheating, replace the defective thermostat or heating element causing the problem. Turn off power before doing any repairs on electrical components yourself.

Follow the manufacturer’s specifications for choosing any replacement parts. A qualified appliance repair technician can assist with testing and replacing parts if you are unsure.

Preventing Hot Water System Problems

Here are tips to help avoid overheated water problems happening again in the future:

  • Set your water heater’s thermostat at 120°F to prevent scalding water.
  • Drain and flush the tank once a year to eliminate sediment buildup.
  • Have an appliance technician inspect the water heater every 2-3 years.
  • Replace heating elements and thermostats that are over 10 years old.
  • Consider installing a tankless water heater that heats water instantly when needed.
  • Install temperature and pressure relief valves as an added safety measure.

What to Do if Hot Water is Dangerously Hot

If your hot water is coming out of the tap painfully and dangerously hot, take these actions right away:

  • Stop using any hot water until the problem is identified and fixed.
  • Check your water heater temperature setting, turn it down if set above 120°F.
  • Shut off the water heater if water is hotter than 140°F.
  • Drain the tank to remove excess heat and hot water.
  • Schedule a repair to replace faulty thermostats or heating elements.
  • Flush the water heater to clear out sediment accumulation.
  • Consider replacing your water heater if it’s over 10 years old.

Key Summary on Dealing with Overheated Hot Water

To recap, the major points to remember are:

  • A broken water heater thermostat is the most frequent reason for suddenly too hot water.
  • Sediment build-up in the tank makes the elements work too hard and overheat.
  • Flushing the water heater yearly prevents scale and sediment issues.
  • Replacing damaged heating elements or thermostats can permanently fix overheating.
  • Keeping your water temperature set below 120°F helps avoid scalds.
  • Technicians can diagnose if elements, thermostats or sediment are causing overheating.

Hopefully this gives you a good understanding of the most common reasons your hot water may be coming out painfully and dangerously hot all of a sudden. Following these troubleshooting guidelines can help get your water heater safely back to making hot water at the right temperature again.