Chimney Liners

Chimney Liners Prevent Excess Moisture

Most furnaces installed today have Annual Fuel Utilization Efficiency (AFUE) ratings of at least 90%.  Since these furnaces use more of the heat produced by the furnace to warm your home, there is less heat in the exhaust gases that are vented outside.  When not vented properly, these lower-temperature exhaust gases could lead to excess moisture in your chimney.

Condensation & Chemistry Lead to Corrosion

If you’ve ever enjoyed a glass of iced tea on a hot summer day, you’ve experienced this “condensation” first-hand. Moisture collects on the glass when warm, moist air condenses on the cold surface. Something similar could happen in your chimney. Warm, moist air hits the cold chimney wall and water droplets form on the inside of your chimney. Condensation was not a problem with your older, less efficient furnace because more of the heat produced escaped up the chimney. According to nature, these hotter vent gases could carry more moisture straight out your chimney.

In higher-efficiency furnaces, exhaust byproducts (vent gases) in your chimney react chemically with the excess moisture to form corrosive acids. Moisture can seep into cracks in the bricks and mortar. In cold climates, the moisture freezes and thaws, and can cause chunks of tile and chimney to break loose. In the worst-case scenario, this debris could actually block the venting system, causing a potentially harmful situation. When not vented properly, excess moisture damage may not be limited to your chimney. Water could even drip back into your furnace, causing it to corrode. As it seeps through porous mortar joints, this moisture could also ruin neighboring drywall.

In situations where a 90% plus furnace is installed, the furnace is “direct vented” using PVC (plastic) pipe and does not vent through the chimney. In these cases, the only appliance left that use the chimney is usually the water heater. The same low-temperature exhaust problem results as described above.

The Difference is Proper Venting

At ARP, we understand how important it is for you to know that a properly vented furnace can eliminate these risks. When we install a new furnace, we will inspect your chimney to see if it could be susceptible to corrosion. If so, we can help you protect against excess moisture with a U.L. listed chimney liner. This metal liner not only provides a physical barrier between vented gases and your chimney, its smaller diameter provides less opportunity for gases to condense. In short, it can significantly improve the long-term reliability of your furnace.

A Few Things You Should Know About Chimney Liners

  • Only a trustworthy heating professional can assure you that your venting system is properly sized to minimize the potential for moisture to damage your chimney.
  • Although installing a proper metal chimney liner requires a small extra cost up front, the costs to repair a corrosion-damaged chimney later can be much greater.
  • A listed metal chimney liner ensures that your home is up to local and national building codes-an important consideration if you ever decide to sell your home.
  • A metal liner will protect you and your home against the effects of condensation, including chimney damage, ruined drywall, corrosion in your furnace a backed-up exhaust gases.
  • We can provide a venting system warranty to insure you against potential chimney damage.


There’s nothing more comfortable than a new high-efficiency furnace. An there’s nothing more comforting than knowing that you have all the facts about proper installation. Please feel free to ask us any questions you may have. After all, the more you know, the more comfortable you’ll stay “inside”!