Why Gas Hot Water Heater Is Not Heating? – Troubleshooting Guide

If a water heater fails to provide you with hot water, then what’s the point of even having one, right? Unfortunately, anyone’s gas water heater might unexpectedly stop heating.

A faulty dip tube, a broken gas valve, and sediment build-up in the tank can prevent the gas hot water heater from operating correctly. The unit might also stop heating, in case the gas supply is turned off and the pilot light, thermocouple, or thermostat had gone bad.  

Why Is My Gas Water Heater Not Getting Hot?

There are a few reasons why your water heater is failing to provide hot water.

  • An inadequate tank size
  • Improper thermostat settings
  • Issues with the pilot light
  • A faulty thermocouple
  • Problems with the gas supply
  • An old gas water heater

Read: What Is Water Heater Heat Pump? Everything You Need To Know

Why Is My Hot Water Not Getting Hot?

At times, the water coming from the water heater is not able to get hot enough. Here are a few things that you can check:

The dip tube

The main job of this component is to ‘push’ cold water to the bottom of the unit. The heated water would then rise to the top, but if the dip tube fails to circulate the water in the tank sufficiently, then the H2O coming from the faucets might be warm or cold.

The gas valve

If your gas valve is broken (this might happen if you have had the unit for over 10 years), then you’ll notice a rotten egg smell. In such a case, the gas wouldn’t be able to effectively heat the water.

Warning! Call an expert immediately, if you suspect a gas leak.

Read: Does HVAC Include Water Heater?

The tank

There might be a lot of sediment build-up in the tank that, in its turn, will lead to slower heating.

A leaking tank might also be to blame.

Gas Hot Water Heater Not Heating – What Can I Do?

  1. Check the gas supply – make sure that the gas is not turned off and that the control knob on the actual heater is not ‘off’.
  2. Take a look at the pilot light or the electronic igniter – one of these elements might be faulty. There can also be a problem with the thermocouple (a safety device that shuts off the gas, if it can’t sense any flame).
  3. Check the thermostat – make sure that the temperature is set to 120 F. You can test, if the thermostat is working correctly by turning the dial-up, opening a tap, and observing the water heater (the burner should ignite). 

What Is the Most Common Problem with Water Heaters?

If the water coming from the heater is cold, then the most common problems include a faulty thermostat, a faulty heating element (for electric heaters), or lack of power (gas supply).

If the water coming from the heater is not hot enough, then the chances are high that the heater is undersized or the hot and cold connections are crossed. A faulty thermostat and heating element might also be to blame. 

Read: Ideal Temperature Of The Water Heater

Does a Gas Water Heater Have a Heating Element?

Unlike an electric unit, a gas water heater does not have a heating element. Gas-powered appliances have a burner that heats the water.

How Do I Know If My Gas Valve Is Bad on My Water Heater?

Your water heater might not be heating, if you have a faulty gas valve – the unit will simply not have enough gas to operate.

The gas control valve contains the pilot light controls and the thermostat (the component is located completely outside the water).

Gas valves rarely fail; however, at times, they might start leaking gas. To check this, apply soapy water to the component – if you see bubbles, then there’s a leak.

You can also try lighting the pilot. If the gas is on, the orifice is not clogged, and the thermocouple is not faulty, but the pilot won’t stay lit, then you have a faulty gas valve.

How Do You Reset a Gas Hot Water Heater?

In the majority of cases, to reset a gas water heater, you would have to reset the pilot light.

  1. Find out where the pilot light is located (consult the owner’s manual or the company’s website).
  2. Make sure that your unit is not leaking gas and only then proceed to the following steps.
  3. Locate the temperature control dial and turn it to the lowest level. Turn the pilot light’s knob to ‘pilot’.
  4. Turn the knob downwards and simultaneously push the igniter button. Let go of the latter, but keep pushing the knob (dial) for around 30 seconds.
  5. If you hear a ‘whoosh’ sound and see the flame, then turn the knob to ‘on’ and adjust the water temperature.

When Should You Hit Reset Button on Water Heater?

When a gas water heater stops heating, then you might want to try resetting the unit.

You can also use the reset button to interrupt the heater, in the event of a malfunction (for example, a power surge or a faulty component).

Does a Gas Water Heater Have a Reset Button?

A water heater’s reset button is typically located right in the center of the limit switch (just above the thermostat).

You’ll find the button next to the limit switch because this safety device can get triggered by the temperature of the water and shut the unit down.

Read: The Best Temperature For The Water Heater And Why?

What Trips the Reset Button on a Gas Hot Water Heater?

The main things that can trip the reset button include:

  • Poor wiring
  • A faulty thermostat
  • A bad high-limit switch
  • A grounding problem

Finally, the reset button will trip, if the water in the heater is way too hot (usually, hotter than 180 F).

How Long Does It Take for Water Heater to Heat Up After Reset?

A tankless gas heater wouldn’t need any time to recover, while a unit with a tank would require around 30-45 minutes.

How Do You Check a Thermostat on a Gas Water Heater?

You can use a multimeter to test if the thermostat is operating correctly.

Place the probe on the terminal screw – you should get a reading of 0. If you don’t get a reading, then the thermostat had gone bad. 

Warning! Don’t forget to turn the power to the water heater off before performing the test.

How Much Does It Cost to Replace a Gas Hot Water Heater Thermostat?

Be prepared to pay anywhere between $100 and $350 to replace your gas water heater’s thermostat. 

How Do I Know If My Gas Water Heater Is Bad?

There are quite a few signs indicating that your water heater might fail soon.

  1. A leaking tank – unfortunately, it’s impossible to replace only the tank; you would have to invest in a new unit.
  2. An old water heater – the closer the unit gets to the end of its lifespan, the higher the chances that it is going to fail.
  3. You started running out of hot water more quickly – this might mean that there is too much accumulated sediment in the tank that leaves less space for the actual water. If you haven’t been regularly flushing the heater, then it might become impossible to remove the build-up.
  4. Inconsistent water temperature – the chances are high that the elements responsible for the heating are broken.
  5. Discolored water – the coating of your heater that slowed down the corrosion is no longer there. You can choose to replace the anode rod and extend the life of the heater, but it won’t be for too long (as the unit is, most likely, already quite old).
  6. Lower water pressure – this means that you might have significant mineral build-up in the unit.

Read: How Much Does It Cost To Move A Furnace And Water Heater?

What Is the Life Expectancy of a Gas Water Heater?

A gas water heater has a slightly shorter lifespan than electrical units. You can expect your gas-powered appliance to last for around 8-12 years

How Long Does a Gas Water Heater Last?

In general, tankless units last a bit longer than the gas water heaters that have a tank

You can prolong the life of your unit if you choose to follow these tips:

  • Flush the water heater every 4 months
  • Book a professional water heater maintenance flush once a year to get rid of the sediment build-up
  • Invite a professional on a regular basis to check the anode rod (it would have to be replaced every 2-5 years) and the pressure valve
  • Check the burner every year