Why Is My Water Heater Smoking – 5 Reasons + Fixes

It’s natural to panic when your water heater starts smoking. These heaters don’t come cheap, and a repair means you have to part with hard-earned cash. It also presents a fire risk if the smoke is coming from an overheating unit.

Thankfully, a smoking water heater is not always cause for alarm. New heaters typically give off smoke in the first minutes of operating it because manufacturers coat these heaters with a thin layer of oil, which quickly burns off after use. 

That may not mean much if your heater is old, though. Any smoke from an appliance is concerning. This article will detail other reasons why water heaters may smoke and how to fix yours.

ao smith water heater

More Reasons Why Your Water Heater is Smoking 

Smoke from a water heater indicates two problems; a minor and a major one. The minor problem is dust and debris buildup burning off when you turn on the heater. The major problem is a burning smell indicating a fire hazard.

When the heater gives off a burnt smell, there’s a chance you’ve got a gas leak or burnt electrical or rubber components. This requires immediate attention.

Why Is My Water Heater Giving Off a Burning Smell? 

You won’t always see a cloud of smoke emanating from your heater. Sometimes, the only sign of a problem is the burnt smell from your hot water tank. This is more concerning than smoke or vapor without the smell.

Why Does My Water Heater Smell Like Burnt Rubber? 

In most cases, the smell of burnt rubber comes from the plastic parts around the control switch or the insulative coating on the wires. The plastic parts or rubber coating may have eroded, exposing the cables to heating elements.

Why Does My Water Heater Smell Like Burning Wires?

The stench of burning wires is unmistakable. Wires burn when electrical components overload. In most cases, your heater smells like burning wire because of a fire rod failure or overheated electrical wiring from exposure to heating elements.

Also referred to as an anode rod, the fire road is a steel wire coated with aluminum or zinc. It protects the metal lining of your heater from explosion or corrosion. 

Like other components in water heaters, the anode rod has a 3- to 5-year lifespan. With time, it cracks and shorts out when exposed to excess current. The extra current heats up the exposed wiring and emits an electrical smell. 

You may also notice the burning wire smell when electric components overheat. After years of use, electric wires exposed to external elements will erode. Furthermore, it will cause a higher resistance, making it difficult for the current to flow through it. 

Note: 10 percent of house fires come from electric water heater tanks. This means exposed wiring and failing fire rods are urgent fire hazards requiring your prompt attention.

Why Is My Tankless Water Heater Smoking? 

It may surprise you that tankless water heaters are not exempt from smoking issues. 

Typically, these models produce a bright blue flame when ignited. However, it may emit black smoke from a gradual buildup of debris. Dirt, pine needles, insect remains, and other debris can build up over time in tankless water heaters, getting burned off when you turn the unit on.

How to Fix Water Heater Smoking Issues 

As a DIYer, avoid tinkering with your water heater if you’re unsure of the problem. Check if it’s giving off a burnt plastic or rubber stench, or if it smells like burning debris or components.

If your water heater smells because of burning debris, flush it to remove the smell. But if it smells because of suspected overheating components, immediately switch the heater off from its power source and call a technician. Don’t try to trace the origin yourself.

Note: Do NOT touch the burnt wires.

What to Do if the Water Heater Smells like Gas?

When using a gas water heater, the smell of gas indicates a gas leak. Immediately turn off the gas valve and open up the windows and doors to allow the gas to dissipate. Then, call your plumber or technician to check and fix the gas leak. 

If you don’t know how to turn off the gas, leave your home and call the fire department for assistance.

Can Water Heaters Cause Fires? 

Yes. The National Fire Protection Association reports electric water heaters alone are responsible for about ten percent of all home fires. Water heaters in general are vulnerable to explosions and fires if their electrical components malfunction. 

The heater may cause fires by sudden combustion or explosion. Sometimes, it starts smoking or gives off a burnt smell in water before a fire outbreak. 

These things place your heater at the highest risk of exploding:

  1. Overheated plastic and rubber parts: As detailed above, these parts can melt away and expose wires or other components.
  2. Gas leaks from a faulty gas valve or pipe: If enough gas gets into the air, lighting a flame nearby will cause it to ignite.
  3. High water pressure: This places pressure on the mechanical components and stresses the system.
  4. Faulty water pressure relief valves: These valves are supposed to keep pressure from building up to dangerous levels in the first place.

In a functioning hot water heater, the safety valve releases excess pressure or the unit shuts down on its own. However, it may explode if the safety mechanisms are defective. 


Fixing a smoking heater is a priority. A delay in finding the source of the problem may cause irreparable damage to the water unit or even risk a fire outbreak. 

Asking for help from a licensed repairer is always suggested for overheating components and gas leaks. In these cases, the most important thing you can do is switch off the gas and power supplies.