water heater smells like burningYour water heater is one of the most important appliances in your home. You need it to wash your dishes, take a shower, or clean your clothes. Because water heaters impact your quality of life in so many ways, it’s important to react quickly when they malfunction, especially when your water heater smells like it’s burning. Though a burning smell is occasionally harmless, in most cases it indicates a serious problem that could endanger the entire unit.

Electrical Fault

When loose wires come into contact with one another, they create a short. Electricity flows in the wrong direction, overloading the wires and generating heat that melts their plastic insulation. Sometimes, in old wires, this build up can create an electrical discharge, known as an arc, strong enough to fry nearby components.

In other cases, electrical contacts can wear out and increase electrical resistance, which prevents power from flowing smoothly into your water heater. Over time, this added resistance generates heat which can melt nearby components.

Both problems can come on suddenly and create a smell of burning plastic. If you suspect your electrical components might be shorting out, go to your circuit box and cut power to your water heater right away. Repairing faulty wiring isn’t complicated, but unless you have experience working with electricity, it’s better to call a plumber rather than try and fix it yourself.

Corroded Anode Rod

The anode rod (sometimes called the sacrificial anode) is a long metal rod, commonly made from aluminum or magnesium, which sits inside your water heater. The rod attracts limestone, iron, and other corrosive particles, “sacrificing” itself to protect the inner lining of your tank.

However, as the rod deteriorates, it can react with sulfite particles in the water, creating hydrogen sulfide gas, which smells like rotten eggs. If you notice the smell when you turn on your hot water, a corroded anode rod is the most likely culprit. (If you notice the smell when you turn on the cold water as well, then your water source is the problem.) Replacing the rod and flushing the system will solve the problem.

Sulfur-Reducing Bacteria

Sulfur-reducing bacteria (SRB) consume sulfur and produce sulfide gas, reducing the amount of sulfur in a system. If they get into your water tank, they make your water stink like rotten eggs, just like a corroded anode rod. Fortunately, its possible to eliminate SRB on your own, without the assistance of a plumber, simply by flushing and purging the tank. First:

  1. Shut off the water
  2. Drain the tank
  3. Reset your water heater to 140°F
  4. Restart the water
  5. Refill the tank
  6. Wait 6-8 hours for the hot water to kill the bacteria
  7. Shut off the water
  8. Drain the tank
  9. Set the water heater to its recommended temperature (normally 120°F)
  10. Restart the water and refill the tank

If the smell persists after flushing the tank, call a plumber. The bacteria may have gotten into other parts of your water system.

Dust and Debris

Old water heaters often accumulate a layer of dust. If your water heater smells like it’s burning, the heat from the surface of the tank may started burning it off. The same thing might happen to any debris that may have fallen on it over the years, like old paint chips. However, you can eliminate the burning smell by powering down the heater and cleaning off the dust with a wet towel or sponge. Once the unit is clean, the smell will be gone.

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