What's Wrong With My Water Heater If The Pilot Won't Stay Lit?

Posted on: 28 June 2016

If you have a gas water heater, it uses a supply of gas to provide fuel to the pilot light, which is responsible for keeping the fire going to continuously warm water. If your pilot light itself won't stay lit, the fire can't run to heat your water. If this happens, there are a few possibilities: there could be a problem with the gas supply line, the pilot tube could be dirty, or there could be a problem with the safety feature known as the thermocouple.

Old or Bent Flex Tubes

Flex tubes ensure a steady supply of gas to the pilot light. If this supply is in any way disrupted, the pilot won't have enough gas to stay on. Check your flex tubing for any kinks or leaks. If there are no kinks but the tubes are very old, replacing them may help. If they are in good shape and have no visible issues, your tubes are probably fine, which means there is another disruption somewhere.

Dirty Pilot Tube

Even though your water heater is running a gas fire, dirt and grime can still accumulate in the pilot tube and the burner assembly as a hole. Luckily, this area isn't too hard to clean. Use the main control dial to turn the pilot off, then shut off the gas supply as well. Wait a few minutes to make sure everything is cool, then remove the burner assembly. To do this, you'll need to unscrew the thermocouple, the main gas line, and the pilot flame gas line. Then you can remove the assembly from inside the water heater.

Once the assembly is out, you can clear off any dirt and debris, then use compressed air to clear out debris from inside the pilot tube. This shouldn't be a difficult process, so don't be too forceful. After everything looks clean, place the assembly back inside, tighten the nuts for the thermocouple, main line and pilot flame line, then turn on your gas supply and try to light the pilot again.

Damaged Thermocouple

The thermocouple is a safety device on your water heater. The thermocouple is supposed to heat up when the pilot light is on; when the thermocouple heats up, it generates an electric charge to keep the gas supply open. Subsequently, if the pilot ever dies, the thermocouple shuts off the supply of gas. This means that if there is any problem with the thermocouple, it may act as though the pilot is not lit, thereby continuously shutting off the water heater's gas supply.

There are a few things you can try here. First, make sure the thermocouple is clean. If it is coated with grime, you can use sandpaper to clean off the end nearest to the pilot light. If you notice that the thermocouple is not close to the pilot light, bend it back to its original position so the thermocouple is touching, or almost touching, the flame from the pilot.

If neither of these things work, you can buy a replacement thermocouple and replace your old one. Your thermocouple typically starts at your main control valve (where you would unscrew it to remove the burner assembly) and ends right over the pilot light. To replace it, simply unscrew the old one from the control valve and remove the other end from the assembly, then feed the new one through until it is in the same place. Screw it in snugly when you are done, make sure the end is touching the pilot, then try to light the pilot again. Contact a business, such as Alexander's Plumbing And Pumps, if you don't feel comfortable making these changes on your own.   

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