How do I stop cold air from coming through my fireplace?

Having cold air come through your fireplace when it’s not in use can make your house feel drafty and cold. There are several things you can try to stop or reduce the amount of cold air coming down your chimney and into your living space.

Quick Answers

Here are some quick answers to common questions about stopping cold air through a fireplace:

• Use a chimney balloon – An inflatable chimney balloon inserts into the flue and inflates to seal and insulate the chimney.
• Install a chimney cap – A cap sits on top of the chimney to prevent outdoor air from descending down the flue.
• Use a chimney top damper – This device closes off the entire chimney flue when the fireplace is not in use.
• Plug the flue – Stuff a chimney plug or inflatable chimney pillow into the fireplace’s flue when not using it.
• Install glass doors – Glass doors seal the front of the fireplace and prevent room air from escaping.
• Seal cracks – Use caulk or weather stripping to seal any cracks around the fireplace opening.

How Does Cold Air Enter a Fireplace?

Cold outdoor air is able to come down your chimney and into the house because of the natural draft that occurs in the chimney. This works like an air current, with warmer indoor air rising up the chimney, which pulls the colder outdoor air down. Even the smallest cracks or openings can allow cold air to be drawn down this draft.

Some reasons why cold air may be entering your unused fireplace include:

• The flue is open – Most chimneys have a damper that seals off the chimney flue when closed. If this damper is left open, it creates an entry point for outdoor air.
• Lack of a chimney cap – A cap sits on top of the chimney stack and prevents outdoor air from descending down the flue.
• Cracks in the masonry or around the fireplace opening – Small cracks allow indoor air to escape and cold air to be sucked down the chimney.
• Improper chimney drafting – Poor drafting can cause outdoor air to be drawn down even when the damper is closed.

Should I Be Concerned?

Letting cold air come through your fireplace is not just uncomfortable – it can also lead to other problems.

Issues caused by a drafty fireplace include:

• Higher heating costs – The cold air forces your furnace to work harder to maintain temperature.
• Moisture and mold – Cold surfaces can cause condensation that leads to material damage.
• Dust and allergens – Outdoor pollutants can enter your home through the fireplace.
• Frozen pipes – Extremely cold drafts could even freeze water pipes near the chimney.

For these reasons, it’s recommended to take steps to block off the cold air drafts when your fireplace is not in use.

How Do I Find the Source of the Cold Air?

Figuring out exactly where the cold air is entering from is an important first step. This allows you to target the specific problem area for an effective solution.

Some ways to detect the source of cold air drafts include:

• Light a small fire – The draft direction will indicate the source.
• Hold a lit incense stick – See which direction the smoke is pulled.
• Use a mirror – A mirror can find daylight coming down the chimney.
• Do a physical inspection – Look for gaps, feel for drafts with your hand, etc.
• Use a smoke pencil – The smoke will get sucked into the draft.

Narrow down where the air is coming from – the damper, cap, masonry cracks, openings around the firebox, etc. Then you can seal up that particular problem spot.

Chimney Plugs and Pillows

A simple solution for sealing a chimney flue is using an inflatable chimney plug or chimney pillow. These are designed to insert into the flue and then inflate to completely block air movement.

Types of inflatable flue blockers include:

• Chimney balloons – Made of durable plastic, these insert in the flue and use a hand pump to inflate. They seal and insulate.
• Inflatable chimney plugs – Similar to balloons but typically made of canvas or vinyl materials.
• Chimney pillows – Filled with fiber insulation and inflate to seal the flue.

When installing one of these flue sealing tools:

• Choose the appropriate size to fit your chimney flue.
• Insert it snugly into the flue, then inflate per the product instructions.
• Make sure it completely seals the flue without large gaps.
• Check and reinflate it periodically since it may lose some air over time.
• Remove it when you use the fireplace to prevent blockage.

Inflatable chimney plugs provide an easy and affordable way to instantly seal your fireplace flue and prevent cold air from descending down the chimney. Just make sure to take them out before lighting a fire!

Chimney Caps

Installing a chimney cap on top of your chimney stack is another excellent option for preventing outdoor air from coming down the flue. It acts as a physical barrier to stop air from entering.

Benefits of chimney caps include:

• Prevent animals, birds, leaves from entering your chimney
• Prevent precipitation from entering, reducing corrosion and damage
• Stop sparks and embers from escaping through the top of the chimney
• Prevent gases and odors from escaping through the unused flue

Along with a chimney damper, a cap can provide full protection when your fireplace is not in use. Key features to look for include:

• Durable metal construction, usually stainless steel or copper
• A 360-degree screen to block air flow from all directions
• A spark arrestor mesh
• A sturdy clamping system to attach it to your chimney

Properly installing a chimney cap involves:

• Measuring the dimensions of your chimney crown
• Selecting the appropriate cap size
• Ensuring the cap completely covers the chimney and flue
• Securing the cap to the chimney using its clamp or screws
• Sealing any gaps with high-heat caulk if needed

Chimney caps are very effective at stopping cold air drafts and come in styles to match your home. They also provide long-term maintenance benefits for your chimney.

Top-Mounted Dampers

Adding a chimney top damper is another excellent solution for sealing your chimney flue when not in use. This type of damper mounts on top of your chimney so it can open and close the flue from above.

Benefits of top-mounted chimney dampers:

• More effective than traditional fireplace dampers
• Can completely seal even large, irregular-shaped flues
• Operate via remote control for convenience
• Provide an airtight seal when closed

For optimal draft blocking, look for key features like:

• A sturdy metal housing to withstand weather
• A thick insulated damper
• A tight sealing gasket
• Corrosion-resistant construction

Installing a chimney top damper involves:

• Measuring your flue size and shape
• Selecting the proper damper to fit
• Mounting the damper on top of the chimney
• Linking the included remote control
• Testing to ensure the damper seals fully when closed

For maximum convenience and cold air blocking, a chimney top damper is one of the best solutions to stop drafts from your unused fireplace.

Glass Fireplace Doors

Installing glass doors on the front of your fireplace can help minimize cold air coming into your house. The doors create an additional barrier between your living space and the fireplace and flue.

Benefits of fireplace glass doors include:

• Reduce heat loss from the room when fireplace not in use
• Minimize cold drafts from the chimney
• Increase efficiency of the fireplace up to 10%
• Protect furnishings and flooring from sparks
• Provide an decorative accent that complements your decor

High quality fireplace doors feature:

• Tinted, heat-resistant tempered glass
• A full seal gasket around the border
• Secure mounting hardware
• Wrought iron, stainless steel, or bronze frame materials

Proper installation is important for maximum effectiveness:

• Accurately measure the fireplace opening
• Choose doors that fully cover the opening
• Install doors securely according to the manufacturer’s instructions
• Check that doors fully close and the latch mechanism works
• Ensure gasket forms an airtight seal when closed

High quality glass doors seal the front of your fireplace to reduce cold drafts from the chimney. Just open them when you use the fireplace to avoid any safety hazards.

Caulking and Weather Stripping

An inexpensive but effective way to reduce fireplace drafts is by sealing cracks and gaps around your fireplace opening using caulk and weatherstripping.

Application tips:

• Caulk – Use a high heat silicone caulk and fill openings between fire bricks and surrounding masonry.
• Weather stripping – Apply adhesive-backed weather stripping around the fireplace opening to seal gaps.
• Ensure surfaces are clean and dry first for proper adhesion.
• Check for cracks behind the fireplace damper as well.
• After sealing, inspect and reseal any areas that still permit air movement.

This method blocks air leakage through small cracks and openings surrounding the fireplace. It provides an added layer of protection against cold air infiltration.

Solution	Cost	Installation Difficulty	Effectiveness
Chimney balloon	Low	Easy	Good
Chimney cap	Medium	Medium	Excellent
Top-mounted damper	High	Hard	Excellent
Glass doors	Medium	Medium	Good
Caulking/weather stripping	Low	Easy	Fair

This table summarizes and compares the main solutions for stopping cold air through your fireplace in terms of relative cost, installation difficulty, and effectiveness.

Prioritize Safety

When sealing up your fireplace, always prioritize safety considerations first:

• Remove any flue blockers before lighting a fire to prevent dangerous gas buildup.
• Have your chimney professionally cleaned before installing caps or dampers.
• Make sure the damper operates properly if installing doors.
• Follow all manufacturer instructions carefully.

Blocking cold drafts should never put your safety at risk. Consult chimney professionals if you have any concerns.

Conclusion

Dealing with unpleasant cold drafts from your inactive fireplace is frustrating. But there are many effective and affordable solutions available. Start by identifying the exact source of the cold air infiltration. Then consider options like chimney plugs, caps, glass doors, and caulking that can seal up those problem spots and provide relief from the drafts. With a few simple upgrades, you can stop the cold air and start enjoying a warmer, more comfortable home.