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Gas Hot Water Heater Not Working? 7 Common Problems and Fixes

Hot water heaters are a godsend in winter and cold weather. When it breaks down, it can affect the whole household, especially for gas hot water heaters connected to storage tanks.

In this guide, we go over the common problems you may encounter with your gas hot water heater. We also discuss fixes for troubleshooting gas hot water heater issues.

What Type of Hot Water Heater Do You Have?

The first thing is to determine what type of hot water heater you have. There are two types of hot water heaters:

Gas hot water heater

This uses natural gas or propane to heat up the water. It commonly has:

  • A gas pipe for supplying gas
  • A pilot light
  • Burner, usually at the bottom of the hot water tank
  • A flue to vent the exhaust fumes

gas hot water heater diagram

Electric water heater

This uses electricity to warm a heating element, which in turn heats the water as it passes through. An electric water heater has:

  • A wire or cable connected to an electric panel
  • A thermostat
  • No flue or exhaust pipe

This guide is for troubleshooting gas hot water heaters. 

7 Common Issues Why Your Gas Hot Water Heater is not Working

No hot water throughout the house

If the water coming out of the tap or shower is cold, it could be due to one several possible issues:


See if the thermostat is not properly adjusted to the correct temperature before checking anything else.

Pilot light

Check if the pilot light is on, and try relighting it (see #6 below). If it still won’t work, then this is a job for the professionals.

Dirty water tank

Impurities in the water supply cause sediment to build up over time. These deposits can settle at the base of the tank, insulating the water from the heating element.

Flush the water tank and make sure there is no mineral buildup at the bottom.

Water is lukewarm

Clogged tank

As noted above, an unflushed tank can have a layer of sediment blocking the water from the heat source. Flush and clean the tank to ensure proper heating.

Damaged dip tube

The water heater dip tube supplies cold water to the tank bottom where it can be heated. A damaged or broken tube releases the flow back to the top where it mixes with the hot water, reducing the overall temperature of the supplied water.


No hot water in a specific part of the house

There may be times when only a specific tap or room doesn’t receive hot water. This indicates a problem not with the water heater but with the water supply.

Closed valve

First make sure the hot water valve  is open all the way, since it may have been dislodged from its open setting or turned off.

Cross connection issue

A cross connection is when a damaged mixing valve allows cold water to pass on to the hot side. This means cold water is getting into the hot water pipe. Replace the shower or mixing valve.

Pipe deposits

The water pipes may have a mineral buildup that restricts the water flow to the hot water pipe. This commonly occurs at elbow joints or old steel pipes.

Ice buildup

Frozen pipes can block water flow to certain areas of the house, especially those exposed colder temperatures. 

See our guide: The 6 Signs of a Frozen Pipe, and How to Fix Them.

Check valve issue

This applies to water recirculation pumps. A broken check valve could be mixing cold water into the hot water pipe.

Dirty or discolored water

Murky or rust colored water is more than just a headache, it can be a health hazard.

Cloudy water

Water that is murky but not rust-colored or red indicates a mineral buildup. Calcium and magnesium are the typical culprits.

This can be resolved by flushing the tank. If the issue happens frequently, it may be due to the water supply of your area. In this case, it may be worth investing in a water softener.

Rusty water

This indicates corrosion problems in the following areas:

If it happens throughout the whole house:

    • Anode rod
    • Water tank

If it happens only to a specific part of the house:

    • Water pipes

If rust is visible in the stored water in the tank, then it may be time to replace the holding tank

Foul odor

Like dirty water, a foul odor emanating from the water can also be dangerous to health.

Bad (but not sulfuric) smell

Bad odors could mean bacteria, which can multiply in the growth-inducing hot water. This is typically resolved by flushing the tank. Experts also recommend replacing the anode rod to minimize the chances of any anaerobic bacteria surviving.

Sulfuric smell

This can be one of two things:

    • The pilot light is out and needs to be relit.
    • There is a problem with the gas line, causing it to leak and leach into the water.

The first one can be resolved in the next section. The second one requires a professional visit from the gas supplier.

No pilot light

The pilot light serves as the ignition source for the gas burner that actually heats the water. It is this part that ignites the gas flowing through the valve, which in turn lights up the burner.

Problems with the pilot light can be caused by:

    • A clogged or worn out tube, which needs to be replaced
    • Loose thermocouple
    • Trapped air in the gas line

If the pilot light will no longer ignite, it could be due to:

    • A defective pilot light, requiring replacement
    • A damaged or broken gas valve

In both cases, call a professional to resolve the issue.

To ensure flawless operation and make your gas water heater last longer, check out our Water Heater Maintenance Guide for Tankless & Storage Units.

If it’s time to replace your tired old water heater, we carry all types of hot water heaters from reputable brands, from storage and tankless models to point of use heaters and hot water recirculating pumps.

Mickey Luongo

Mickey is the resident heating and air conditioning expert with over 15 years of experience in the industry.

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