uneven temperatures in your home

Your furnace's exhaust and air intake flues are important to keep your furnace running efficiently and to vent dangerous gas from your home. As you get your furnace ready for winter, it is a good idea to inspect your furnace flue for some common problems. Here are two common problems that can occur with your furnace exhaust and air intake, and how you can get them corrected.

Blocked Flue Vent

A clogged or blocked furnace flue air intake or exhaust pipe can cause your furnace to have trouble starting or to not start at all. If your furnace has begun to have problems running, you should check the intake and exhaust pipes to make sure they are not blocked with anything. Cold weather or heavy snowfall can cause a blockage on the exterior opening of the air intake and exhaust for your furnace. Ice can build up from condensation created as hot air exits and cools from the exhaust pipe, which can block the exit. Snow can collect around the opening of your exhaust and air intake pipes, blocking them. Other types of clogs can be caused by leaves, trash, or other debris covering an opening. 

Some furnace flue pipes exit from the roof of your home, others from your home's foundation. Check to see where your furnace's exhaust pipes exit away from your furnace and out your home. Then, look on the outside of your home to see if you can see any blockage on the openings. 

If you have bushes or plants growing around a foundation-exiting flue, it is a good idea to make sure they are not a potential blocking hazard. Keep any bushes or plants trimmed from a three-foot area around the exhaust and air intake pipes. If the vent pipes exit from your rooftop, use a ladder to reach the vent and exhaust pipes. Check roof vents to make sure there are no bird or other animal nests blocking the openings of the pipes. 

Flue Condensation Dripping 

The flue exhaust pipe exiting your home's furnace allows heated gas and vapor to escape your home. Because most of the gas exiting through the flue pipe contains a large amount of water vapor, there is a potential for condensation to form and drip back down the flue, into your home or back into your furnace. This occurrence can cause corrosion and damage to the exhaust flue. Prolonged condensation dripping back down your exhaust pipe can cause the pipe to rust and corrode. Over time, this can allow leaks to form and carbon monoxide to enter into your house.

The main reason condensation can begin to drip back into your furnace is because the flue is the wrong size for your furnace. This may be because your furnace was installed improperly, with the wrong-size or type of flue being used. An exhaust pipe that is too large can allow too much air to circulate inside it. This makes it difficult for the warm gas and water vapor to create a strong enough updraft to push the exhaust out the vent. This results in cold air from the top of the pipe pushing the warm air back down, trapping it to create condensation.

Condensation may also be dripping because you have upgraded your furnace, but the flue was not upgraded along with it. Newer furnaces can be more efficient, causing them to push most of the heat they create into your home instead of out the flue. Then, because the exhaust air and flue are more cool, condensation can form more easily as it travels through the exhaust pipe. 

If you find condensation dripping from the pipe into your furnace, have a repairman from a company like Mike's Bremen Service Inc check your furnace. The repairman can determine and install the right size of flue your furnace needs. They can also check your furnace for any carbon monoxide leaks into your home, especially from the exhaust flue.

Check your furnace for both of these problems so you can make sure they are corrected.