Why is my water only getting warm?

Author: Kailyn Hermiston  |  Last update: Monday, May 19, 2025

As water collects inside your hot water heater to be heated, it's common for debris in the water—like sand, dirt, and minerals—to settle at the bottom of the tank. As the particles collect on the bottom of the tank, the water heater can't effectively heat your water, resulting in lukewarm water only.

Why is my hot water only coming out warm?

Here are a few potential reasons why your hot water might only be coming out warm: 🚱 Faulty thermostat 🚱 Leaking hot water pipes 🚱 Broken heating element 🚱 Water heater settings 🚱 Sediment buildup If you are experiencing any of these issues and you're not comfortable troubleshooting your hot water heater your.

Why is my water not getting very hot?

A lack of hot water can be caused by a variety of issues. In electric water heaters, a power loss or heating element failure can cause water to no longer heat in the tank. In gas water heaters, a faulty gas connection, a bad pilot light, or a bad burner can cause no water to heat.

Why is my hot water only hot when the heating is on?

A diverter valve may be faulty if your water is lukewarm, if your hot water taps work but your central heating does not or if your hot water taps only work when the central heating is on.

What is the first thing to check when there is no hot water?

Check the circuit breaker.

If you have an electric water heater, the first thing to check when experiencing hot water issues is your circuit breaker. A tripped circuit means the current was disrupted. As a safety measure, the circuit breaker flips.

How to Fix a Cold Radiator 4 Easy Ways | DIY Plumbing

What is the most common cause of no hot water?

The most obvious reason for a lack of hot water is if your power or water supply is disconnected from your boiler. Whether you have a gas or electric boiler, it is essential that the right fuel is being supplied to the system at all times, as well as water arriving from the mains or from a separate storage tank.

How to fix no hot water in shower?

First, find the shut off valve for the hot water and see if it's closed. If so, opening the valve could remedy the situation. But if the water still remains warm for only short periods of time, you may have a blockage or obstruction in the pipes or a problem with your bathroom shower valve.

How to unstick a diverter valve?

Well, that brass knob, known as the diverter valve, that connects pipes in your combi boiler might be the culprit. But you won't be able to free a stuck diverter by yourself; a qualified heating engineer will need to be called in to save the day.

What are the symptoms of a faulty diverter valve?

Symptoms of a faulty diverter valve often include inconsistent hot water flow and radiators not heating properly. Homeowners may notice that radiators remain cold even when the boiler is on. Inconsistent water temperatures are common, with water switching from hot to lukewarm or cold unexpectedly.

What position should a 3-port valve be in?

The valve should go to the mid position with both Port “A” and Port “B” open. The boiler should fire and the pump should run. The pipes connected to Port “A” and Port “B” should get hot. Once satisfied with the valve operation, reset the programmer and the thermostats to normal control settings.

What are the symptoms of a bad thermostat on a hot water heater?

Signs Your Water Heater Thermostat Is Faulty
  • You have no hot water.
  • You're running out of hot water quickly.
  • The water is too hot.
  • It takes a long time for your water heater to heat the water.
  • You keep having to reset the high-temperature limit switch.

Why is hot water not coming out of my tap?

There are several reasons why you might not have hot water, ranging from common problems, such as a problem with your water or power supply, boiler settings, thermostat, timer, recent power cut to more complex issues, such as boiler pressure, a potential airlock or frozen pipes.

How often should I flush my water heater?

Most homeowners should flush their water heaters every 6 months or so, but if you have extremely hard water, you may want to do it more often. Flushing your hot water heater could be necessary as often as every few months depending on the mineral content of your local water supply.

Why is my water suddenly not hot enough?

Inspect the thermostat, which controls hot water heater temperature. If someone has recently changed the setting, that could be the reason behind your lukewarm water woes. However, if the temperature setting is correct, the thermostat itself might be broken. You can have the thermostat replaced fairly inexpensively.

Why is my shower lukewarm at its hottest?

Your shower mixing valve controls the water temperature of your shower by blending together cold and hot water. Sometimes, though these valves wear out, break, or are positioned incorrectly and that can cause uncomfortable shower temperatures.

How to tell if your hot water heater is bad?

Water heaters show several signs of going bad, including lack of hot water, temperature fluctuations, decreased water pressure, strange noises, rotten egg smell, visible leaks, rusty or discolored water, and increased energy bills. If your water heater is over 10 years old, it may be time to consider a replacement.

How much does it cost for a plumber to replace a diverter valve?

$100 – $350 shower cartridge replacement cost

Plumbers charge $100 to $300 in labor alone to replace a shower mixing valve or diverter valve.

Can you reset a diverter valve?

We recommend that you don't try to fix the stuck diverter valve, and would be ideal to leave it to a fully qualified professional. If you're having issues, then give BOXT a call on 0800 193 7777. Our in house engineers are specialists on the subject of boilers and are happy to help.

Where is the hot water diverter valve located?

Conclusion. The diverter valve is an essential part of a combi boiler, generally found within the boiler's main body near the main heat exchanger. Its primary function is to direct hot water to the radiators for heating or to the taps for domestic use.

Can a diverter valve unstick itself?

A stuck diverter valve on a combi boiler isn't a DIY fix. That's because you're dealing with electrics and gas components. Only a Gas Safe registered heating engineer can repair a stuck or faulty diverter valve.

How do you free a stuck hot water valve?

Use your hair dryer to heat up the valve body to melt any gunk and grime that's built up and solidified into an adhesive. Once you can feel the valve turning, wiggle it back and forth to let the gunk and grime wash away. Use your wrench to loosen the bonnet or packing nut.

Is a diverter valve easy to fix?

A diverter valve boiler issue is a widespread issue with combi boilers that are older. Over time, the diverter valve wears out or breaks, causing havoc on your central heating system. You should note that fixing a faulty diverter valve on a boiler might be an easy task, but it can also be expensive.

Why does only my shower not have hot water?

So, when your shower's not getting hot water but your sink does, this situation may point to a faulty anti-scald unit. Perhaps your unit is improperly adjusted or even in disrepair. A professional Mustang plumber can check if your anti-scald unit is the culprit.

How to tell if a shower valve is bad?

The most obvious indication that plumbing repair is needed to fix a malfunctioning shower valve is when the knob is harder to turn or will not turn at all. This problem is a sign that the valve is either out of alignment, preventing it from functioning correctly, or something is broken.

Why is my shower only running cold water?

If your shower isn't getting hot, the issue could stem from a variety of factors, such as a faulty thermostat, a broken mixing valve, or issues with your boiler or water heater.

Previous article
How common are tree roots in a sewer line?
Next article
Are porcelain sinks outdated?