Do I Need a Chimney Liner For A Gas Furnace? Need To Know


Rima Chatterjee

Gas furnaces produce gasses and moisture which can harm chimney walls or masonry. This could cause damage and also result in chimney fire and toxic fumes like carbon monoxide entering the living space. 

In this blog post, we will study the necessity to get a chimney liner to save your gas furnace and your life.

What Is A Chimney Liner?


Chimney liners are the protective layers that are essential for any venting system used for oil, wood or gas appliances like water heaters, gas logs, and gas furnaces. 

Regular maintenance provides longer lifespan support. Never install retractable awnings near chimneys, as they trap steam inside releasing high temperatures which may damage your structure.

Types of Chimney Liners


To determine the right chimney liner for your gas furnace, you need to consider the type of liner that fits your needs. 

  • Clay tile liners
  • metal liners like stainless steel 
  • cast-in-place liners are the most common types that most homeowners consider. 

Clay Tile Liners

Clay tile liners are a great go-to option for chimney lining. Let’s explore the different types and their features.

Straight flue liners 

It comes in a range of 6″x6″ to 12″x12″ and is known for being durable, fire-resistant, and low-cost. However, they can only be used for straight chimneys and are difficult to install or repair.

Terra cotta liners 

It comes in sizes ranging from 6″x8″ to 13″x13″ and is precast from high-grade terra cotta clay. This makes them long-lasting, but maintenance is necessary after every use and they’re not suitable for combustible materials like gas.

Metal Liners Or Stainless Steel Liners

Metal liners, especially stainless steel ones, are popular for chimney lining. Different types offer various advantages. 

Rigid liners 

They are great for straight chimneys. Professional installation is needed due to their rigidity. 

Flexible liners 

They can go around bends and turn. They are easy and cost-effective to install. 

Insulated liners 

They are useful for older, uninsulated chimneys. They stop condensation from forming inside the liner.

Here’s a table:

Type of LinerMaterialDiameterWall Thickness
Rigid304 SS3″-16″0.018″-0.038″
Flexible316L SS4″-12″0.006″-0.02″
InsulatedDouble-wall SS + Ceramic Fiber Insulation3″-12″Varies on insulation thickness

Cast-In-Place Liners

Cast-In-Place Liners are special. They are custom-fit to prevent heat loss and flue gas penetration. Their thicker walls give them better insulation. 

Purpose of Using Chimney Liners


To ensure the safety and efficiency of your gas appliance, it is crucial to understand the importance of chimney liners. 

With the potential for excess moisture, carbon monoxide, and toxic fumes, a properly sized chimney liner is essential in keeping your home and appliances safe. 

Chimney liners are essential for safety and durability

They protect your home from dangerous carbon monoxide. Without a liner, heat can damage attic beams, walls, and anything close by. Over time, it can cause cracks and leaks of carbon monoxide.

Liners act as a barrier

They improve ventilation, so fumes escape outside. They come in materials like stainless steel and aluminum, which resist acid attacks. Plus, they preserve heat until it exits the chimney. And, they help air move inside the chimney.

70% of homes have chimneys without liners

This puts them at risk of fires or carbon monoxide leaks. Get a liner installed for your family’s safety. It’s a great way to prevent accidents.

Benefits of Using Chimney Liners


Chimney liners protect the inner walls of chimneys from heat, smoke, and harmful gases. Without one, your home is at risk. 

Installing a liner can increase fireplace efficiency by 20%. It also comes in rigid or flexible forms for different chimneys.

Liners provide safety and many benefits, like:

  • Low maintenance.
  • Improved furnace performance.
  • Extended life of chimneys.
  • Increased energy efficiency.
  • Chimney liners are now one of the most beneficial components for a home with a fireplace. 
  • They enhance safety and performance. 
  • Investing in a lining can make a big difference in creating an optimized heating solution that keeps you safe.

How To Select the Right Chimney Liner?


In short, selecting the correct chimney liner is essential for efficient ventilation and safe operation of the appliance. 

Consider appliance size and type, local building codes, and fuel type when choosing both pipe diameter and material. Consult a professional installer to ensure proper installation.

Based On Appliance and Ventilation System Size

When selecting a chimney liner, size matters. Consider the appliance and ventilation system size before purchasing. 

The table below outlines the required pipe diameter for various appliance sizes:

Appliance SizeRequired Pipe Diameter
Under 35,000 BTUs3 inches
35,000-75,000 BTUs4 inches
75,000-150,000 BTUs5 inches
Over 150,000 BTUs6 inches

Chimney liner material should also be chosen based on the amount of heat produced by the appliance. 

For example, 

Stainless steel works best for wood stoves and furnaces, while aluminum is better suited for gas fireplaces.

Based On The Types of Fuel Used

Choosing the right chimney liner is key to having a functional fireplace. 

Here’s a breakdown based on fuel type:

Fuel TypeLiner MaterialKey Features
GasAluminumDurable. Corrosion-resistant. Lightweight.
Oil and Gas Wood Chimney LinerStainless SteelDurable. Rust-resistant. Easy to install. Suitable for high-heat conditions.
Retrofitting Existing Chimneys or Wood Burning Appliances (Wood Combustion)Ceramic Flue Liner Cast-in-place LinerPour-in-place Masonry Liners Mineral WoolSuitable for high-heat conditions.

Excess Moisture and Ventilation

Excess moisture in your chimney can cause lots of problems. For property damage and health issues, proper ventilation is key for getting rid of fumes and moisture.

When installing a liner, ventilation is essential. It creates a channel for the smoke and moisture to escape. No interior or exterior damage.

Installing a New Chimney Liner


To install a new chimney liner with a solution for your gas furnace, you must know about the repair process, cost considerations, and retractable awnings. 

Let’s understand the repair process involved in chimney liner replacement and how retractable awnings can affect chimney efficiency. 

Additionally, cost considerations play a vital role in determining the type of liner you need for your gas furnace.

The Repair Process

Chimneys can suffer damages and require repair. If you’re experiencing problems with your chimney, like leaks or deterioration, it might be time to install a new chimney liner. 

Here’s what you need to know.

AssessmentThe first step is to assess the damage and find out if a new chimney liner is needed. This is done by inspecting for cracks or other signs of wear. A professional chimney sweep will also check for blockages that can cause poor ventilation.
Making RepairsIf a new chimney liner is needed, repairs can start. The existing liner will be taken out, and the new one will be installed using stainless steel or clay tiles.
Final InspectionAfter installation, a final inspection will happen to make sure everything was done right. Inspections usually cover draft testing, creosote buildup, proper ventilation, and look for any defects that could cause safety issues.

Retractable Awnings

Retractable Awnings are a great addition to any home. They provide shade on demand, and protection from wind, rain, and harmful UV rays. 

There’s design versatility with various styles and designs, plus, they’re durable and conveniently operated with the push of a button or remote control. 

Moreover, Retractable Awnings are energy efficient, decreasing indoor heat up to significant percentages. They also protect health by blocking the entry of UV radiation.

Enjoy outdoor living with optimal comfort during summer days and mild evenings. 

Retractable Awnings add value to the property, being economically feasible as it helps save money spent on cooling systems.

Cost Considerations Of Chimney Liners For A Gas Furnace

Cost is a big factor to think about when putting in a new chimney liner. To help with an idea of what it’ll be, here’s a list of the costs:

Type of Chimney LinerMaterial Cost per FootInstallation Cost per Hour
Clay Tile$10 – $20$50 – $70
Stainless Steel$40 – $100$65 – $85
Cast-in-Place$40 – $100$90 – $110

Maintaining Chimney Liners


To maintain your chimney liner for maximum safety and efficiency of your gas appliance.

You need to know about the signs of damage and deterioration to your liner, as well as the process of cleaning and repairing chimney liners. 

Signs of Damage and Deterioration In Chimney Liners

Keeping your chimney liner in check is essential to the safety of your home. Recognize the signs of damage and deterioration.

  • Cracks in the lines are a warning sign that dangerous gasses or flames can escape.
  • Watch out for deterioration, when moisture seeps into the walls and weakens them.
  • Discolored walls and rust-colored stains are signs of excessive moisture.
  • Creosote buildup is also flammable and can be dangerous if it accumulates.
  • Observe any obstructions in the chimney, these suggest maintenance and cleaning is due.
  • Prioritize your safety – contact a professional today if you’re worried about your home’s security.

Cleaning and Repairing Chimney Liners

Cleaning and repairing chimney liners is important for the safety of your home. Maintenance can stop fires, carbon monoxide leaks, and structural wear. 

Here’s a guide:

  1. Check the liner for cracks or damage.
  2. Clean the liner with a wire brush or power drill with a chimney brush attachment.
  3. If the liner is damaged, measure it for a replacement.
  4. Remove the old liner and install the new one.
  5. Seal all joints between sections of the new liner using a high-temperature sealant.
  6. Test your fireplace to ensure proper airflow.

Cleaning can stop creosote buildup damage. Consider a chimney cap to stop debris from entering and damaging your liner.

A National Fire Protection Association study found that 30% of home heating fires were caused by not cleaning chimneys.

Safety and Risks Considerations Of Using A Gas Furnace


To ensure your safety while using a gas appliance like a furnace or water heater, it is imperative to be aware of the potential risks and take proper precautions. 

Carbon Monoxide and Toxic Fumes

Carbon monoxide and toxic fumes can be a real headache! They’re often colorless and odorless, making them hard to detect. 

Even small amounts of CO can be lethal, so having a reliable carbon monoxide detector is key.

Exposure to these poisons can be caused by gas-powered appliances, wildfires, and vehicle emissions. 

When inhaled, they replace oxygen in your blood, leaving you with symptoms like headaches, dizziness, nausea, chest pain, and shortness of breath.

We can learn from past cases of carbon monoxide poisoning and toxic fumes exposure too. 

For example, 

The Donora Smog 1948 incident in Pennsylvania resulted in 20 deaths and 6,000 sick people due to industrial pollution.

Precautions like proper ventilation systems and staying aware of natural disasters that can cause high levels of airborne pollutants are important.

Chimney Fires

Chimney fires can be devastating. Creosote, built up in the chimney, can ignite and spread flames throughout the home. Flammable material nearby can fuel the fire, resulting in more destruction.

To lessen the danger of a chimney fire, have professionals sweep your chimney to get rid of all the creosote. 

Regular inspection of the fireplace and chimney can spot any faults early and fix them before escalating.

Never leave a fire alone or let it burn overnight. Instead, put it out before going to bed or leaving for a long time.

By following these tips, you can reduce the risk of a chimney fire in your home. And remember, safety is not only a state of mind but also a state of being safe from falling pianos.

Conclusion


As a homeowner, caring for and maintaining gas appliances is essential – such as the gas furnace. Installing a chimney liner is vital to ensure efficient and safe operation. Liners guard the entire area of the flue and chimney walls against corrosion and condensation caused by hot exhaust gasses. 

About the author

Debarghya Roy: A heating systems author, Passionate about energy efficiency and sustainability, Sharing insights and empowering readers through informative blog articles.