How to Unclog the Vents and Pipes in a Natural Gas Water Heater

A natural gas water heater.
  • 2 hours
  • Intermediate
  • 0-500
What You'll Need
Plumbing snake
Garden hose
Slip-resistant shoes

If the vents and pipes in a natural gas water heater are clogged, it could lead to serious health issues due to the release of carbon monoxide and other dangerous gases inside the home. Below are steps on how to unclog and maintain vents and pipes to ensure home safety.

Step 1 - Determine the Cause of the Clog

There can be multiple causes of clogs in the vents and pipes. Most likely, the vent is clogged by debris or its opening is obstructed. Follow the vent pipe to check how it connects to the outside. Usually, the vent opening can be found at the roof or at an exterior wall. If the opening is up on the roof, wear slip-resistant shoes, get a ladder, and climb the roof to inspect it. Remove any obstruction on the vent opening. Leave the water heater on. Put your palm just above the opening to feel if there is any air draft. If there isn’t then there must be something obstructing it within the vent pipe.

A bent portion or exposure to extreme freezing temperatures can cause a clogged pipe. Although hot water runs through the pipes, it cannot get to its destination when a certain length of it is frozen.

Step 2 - Clean the Vent Pipe

Wear a mask, safety goggles, and protective gloves. Climb up the roof and remove the vent covering. Use a flashlight to see through the pipe hole. Inspect if there is any obstruction. If the vent is curved, insert a garden hose inside its opening and let it reach down. When the garden hose stops at a certain distance, there is something clogging it. Rent or buy a plumber’s snake and insert it into the vent pipe until it reaches the obstruction. Turn the snake until it hooks to the clog and pull the snake out.

If the vent pipe is connected to a main vent, pour water into the main vent’s opening until it flushes the dirt and debris. Turn on the water heater and check for air draft. If there is airflow, the problem is solved.

Step 3 - Unclog Pipes

If the water pipes are clogged during the winter season, inspect the location of all pipes and determine if any of them are exposed to the freezing cold. If some of the pipes are located outside the home for some reason, purchase spray foam insulation and insulate every inch of the pipes. This will avoid having the cold clog the pipes.

If a certain portion of the pipe is bent, replace it with a new one. Purchase the needed pipe length and connecting equipment. Turn off the machine and the water supply. Make sure that all the water is drained before proceeding with the work. Cut the bent pipe and install the replacement. Connect the pipes accordingly depending on the material used, such as PVC, copper, steel.