Dangers Of Two Heating Problems And How To Prevent Them

Your home's heating system is important for keeping your family warm during the winter, but it can also pose a danger to you. Here are two common home heating system problems, the dangers they pose, and how to prevent them.

Leaking Chimney or Furnace Flue

You cannot see or smell carbon monoxide poisoning, and it kills about 4,000 people in the United States each year. Carbon monoxide is one of the most common dangers introduced by your home's heating system, especially when you don't maintain it to keep it working properly. In a poorly-vented flue, the vapors from your furnace can cool inside the flue and turn into condensation, which drips back down the flue. Eventually, this condensation can corrode and rust sections of the flue, creating holes and cracks through which carbon monoxide can leak back into your home. 

Condensation can become a problem inside your heating ventilation flue for several different reasons. One reason is because the right flue was not installed for the type of furnace you have, or you upgraded your furnace but the HVAC installer did not upgrade your flue as well. Because the vapors traveling up your heating flue are mostly water, they can condense if they cool while inside the flue. If you have a more efficient furnace, the fumes given off by your furnace are going to be cooler, so the flue needs to allow the vapors to vent quickly. But if your flue is too wide, it can also allow cool air to enter the top and push the warm air down, preventing the updraft needed to allow the warm air to exit the flue, and cause condensation to form. 

Blocked Chimney or Furnace Flue

A blocked chimney can cause a chimney fire and carbon monoxide to enter your house. When smoke from your fireplace travels up your chimney flue, it cools and condenses into creosote. Creosote is a black soot that will stick to the surface of your chimney flue, collecting into a thick layer. Then, this soot can heat up and catch on fire.

When you have the first chimney fire, you may not be aware it has even happened, but it can cause cracks in the mortar of your chimney. Toxic fumes from your fireplace can leak through the mortar cracks and into your home, potentially causing carbon monoxide poisoning. Then, the next chimney fire you have can more easily spread to your home's roof through the cracks.

If you have converted an oil furnace to a gas furnace, still using your chimney as the vent, this can pose a problem. The gas vapors combine with the old soot deposits left inside the original clay chimney liner and can cause the clay liner and the soot to flake off and collect at the bottom of your chimney flue, causing a blockage. A blocked furnace flue can cause toxic fumes from your furnace to enter your home. 

Any type of debris from animals or plants can also clog up the flue and push the toxic fumes back into your home. During the combustion in your home's heating system, nitrogen dioxide, carbon monoxide, and acidic water vapors are created. Both of these are toxic and can escape into your home from a blocked flue.


The best way to make sure your furnace flue or chimney are not leaking is to have them properly inspected every year by a trained HVAC technician. It is recommended to have your chimney cleaned once a year along with an inspection if you use it less than three times a week. 

If you suspect your flue is the wrong size for your heating system, have an HVAC repair service inspect it to see if it is the right size. Then, the technician can make sure the size of your flue is adjusted to prevent cooling and condensing of vapors inside the flue. 

Make sure you have a carbon monoxide detector in your home. Then, your HVAC technician can also check for any carbon monoxide leaks in your home from a leaking furnace or chimney flue and prevent you or your family from getting carbon monoxide poisoning.