what is a thimble in a chimney

by Ettie Harvey Published 3 years ago Updated 2 years ago

The thimble is the round opening that can be found in a brick or stone chimney about five feet above floor level. The thimble enters the flue inside the chimney at a 90 degree angle and is designed to accommodate the entry of a stovepipe from a wood stove.

Full Answer

What is a chimney thimble used for?

An important part of chimney installation is the chimney thimble. In most cases, this is a piece of metal that fits into the hole where the chimney will exit your wall. This is used when connecting something like a wood stove to a chimney. Chimney thimbles come in a variety of thickness.

Where does the Thimble go in a wood burning stove?

The thimble enters the flue inside the chimney and is designed to accommodate a stovepipe. If the homeowner no longer uses the wood-burning stove, the pipe is removed, and the thimble port is covered over by drywall, wallpaper, or a pie-plate cover.

What is a thimble trowel used for?

Margin trowel. An important part of chimney installation is the chimney thimble. In most cases, this is a piece of metal that fits into the hole where the chimney will exit your wall. This is used when connecting something like a wood stove to a chimney. Chimney thimbles come in a variety of thickness.

How does a thimble flue work?

Do I need a chimney thimble?

Running any residential or building heating appliance, burning gas, liquid, or solid fuels through a combustible wall, will require an Insulated Wall Thimble as your passageway to connect appliances to interior or exterior masonry chimneys.

How do you fix a cracked flue thimble?

To repair a crack, mix the mortar to a fairly watery consistency so that it's easier to work into the cracks. Fill the cracks from both the inside and the outside of the thimble. Use refractory mortar, a special kind of mortar that is resistant to the high temperatures that will be present in a chimney thimble.

How do you install a chimney thimble?

Apply a layer of stove cement to the edges of the opening, using a trowel. Install the thimble by simply sliding it in place so it extends to the inner edge of the chimney liner, but not past it. Apply additional stove cement to fill any gaps and to seal the thimble securely. Let dry.

How do you close a chimney thimble hole?

The proper way to close off a thimble port is with brick and mortar to create a solid and safe enclosure. It's important that your chimney service technician checks that the area that gets closed off has a lining. If there's no lining due to the flue, then a new one needs to be installed.

Can a cracked chimney flue be repaired?

If your flue liner is cracked, this is the solution: a stainless steel insert. It's placed down the entire length of the flue, sealing the old liner. It's a job that can be done by a professional in just a few hours.

How much does it cost to install a chimney liner?

The average cost to have a chimney lined by a professional is going to be about $2500. Depending on the type of chimney liner, it could cost up to $10,000. The average DIY chimney liner installation is going to cost about $750 and could cost as high as $3000 for the material.

What is the requirement for thimbles installation into a masonry chimney?

Things You'll Need The thimble is the round opening that can be found in a brick or stone chimney about five feet above floor level. The thimble enters the flue inside the chimney at a 90 degree angle and is designed to accommodate the entry of a stovepipe from a wood stove.

Why is there a hole in my fireplace?

An ash pit is a hole in your firebox in which old ashes can be placed. Its convenient location allows you to sweep in any ashes and embers, then seal them in by closing a small door. Ash pits are designed to withstand the heat from your fireplace while being easily accessible for the homeowner.

What is a masonry thimble?

A masonry thimble is a round, terracotta cylinder extending through the chimney wall into the flue. The hole is usually 6 or 8 inches in diameter and is designed to accept stove pipe.

Should unused chimneys be capped?

Capping is undoubtedly the best option when it comes to dealing with your unused chimney. Failure to secure proper chimney ventilation could damage your chimney and roofing.

Can I block a chimney with expanding foam?

Expanding foam won't allow the flue to breathe. Capping the chimney may help cut down draughts, and is a 10 second job to insert a ventiator that keeps rain out but allows some air to flow, but only once you are up on the roof and can get to the chimney pot!

How do you stop a fire in a fireplace?

0:061:13Fireplace Maintenance : How to Put Out a Fire in a Fireplace - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd you're trying to put it out is to pour water on it you want to smother the fire. Because whatMoreAnd you're trying to put it out is to pour water on it you want to smother the fire. Because what you're going to do if you pour water on it you're going to create a lot of steam.

How do I fix a crack in my chimney?

You'll need to call a brick mason or chimney sweep that specializes in chimney repairs. Minor cracks (up to 1/8″ wide) in bricks that are not loose can be filled with brush-applied crack filler, as can loose or missing mortar joints.

How do you repair a cracked clay chiminea?

Apply the automotive repair putty or high temperature epoxy adhesive to the cracked or broken part of the chiminea. Apply enough putty or adhesive that it mounds up slightly on the surface of the clay. Use a clamp to clamp any broken pieces onto a firm section of the clay before applying the putty or epoxy adhesive.

Can you repair a clay chimney liner?

When a clay chimney liner has deteriorated, Cast-in-Place is an option that allows you to restore the liner without the complications or expense involved with rebuilding. Most masonry chimneys are built with clay tile liners because they are economical and durable.

Can you repair the inside of a chimney?

The two types of services include partial and complete rebuilds. A partial rebuild works best for small chimneys where scaffolding isn't required. A partial rebuilding means you only need one part of your chimney replaced, such as the crown. This type of rebuild is for chimney's that only have damage at the top.

What is an insulate wall thimble?

Why do you need a thimble for venting?

Wall thimbles are an important component for venting stoves and other appliances since the thimble will insulate between the pipe and the wall, to protect drywall, wood frames and other materials from high temperatures and risk of fires. Insulated Wall Thimbles are designed so the thimble assembly will reduce the minimum 18 inch clearance to combustibles, to a minimum of at least 2" clearance. You should pack insulation snugly against the outside box frame of the thimble, but never place insulation into the area within the thimbles's cylinder.

How much clearance does a thimble need?

Insulated Wall Thimbles are designed so the thimble assembly will reduce the minimum 18 inch clearance to combustibles, to a minimum of at least 2" clearance. You should pack insulation snugly against the outside box frame of the thimble, but never place insulation into the area within the thimbles's cylinder.

Why do chimneys have fires?

A major cause of chimney related fires, is failure to maintain required clearances (air space) to combustible materials. It is of utmost importance that the Insulated Thimble be installed only in accordance with their instructions.

What is a thimble in a chimney?

What is a thimble port?

One of the most common discoveries that historical homeowners often come across is a chimney thimble port; a circular hole in the wall used to house a thimble. The thimble enters the flue inside the chimney and is designed to accommodate a stovepipe. If the homeowner no longer uses the wood-burning stove, the pipe is removed, and the thimble port is covered over by drywall, wallpaper, or a pie-plate cover.

What happens if you don't have a lining on your chimney?

If there’s no lining due to the flue, then a new one needs to be installed. Otherwise, there’s a possibility that the pie-plate will overheat.

How to tell if a hole is patched in masonry?

You can check for a poorly patched hole in the masonry repaired with aluminum pieces or bulges behind drywall or wallpaper, but the only way to know for sure is with a video scan.

Is a thimble hole in a chimney dangerous?

Thimble ports are hazardous. Unused thimble holes in chimneys are as dangerous as any breach in the chimney’s structure. Removing a previously existing stovepipe allows creosote to collect in the thimble that eventually ignites and spreads to the surrounds studs.

How to replace the chimney thimble

If the thimble is slightly cracked, you should go ahead and repair it. To do it you need to mix mortar to a fairly watery consistency to be able to easily work with it into the cracks. For ideal results, you should fill the cracks from both the inside and outside of the thimble.

Conclusion

These are tips on how to undertake chimney thimble replacement. While you can replace the thimble if you have masonry skills, you should consider hiring a masonry chimney repair professional to if you don’t have the necessary skills.

What is a chimney thimble?

In most cases, this is a piece of metal that fits into the hole where the chimney will exit your wall. This is used when connecting something like a wood stove to a chimney. Chimney thimbles come in a variety of thickness. Choosing a thick chimney thimble will provide a better fit when you are installing your chimney pipe. Because the chimney thimble must be cemented in using a high temperature cement, the installation of the thimble is best done during the installation of the remainder of the chimney.

Can you use a chimney kit with a thimble?

Your chimney kit may have screws that you can use to attach the thimble to the wall. It is okay to use those, however, most building codes will require that you use a high temperature cement in addition to the masonry screws to insure proper and safe installation.

What connects the stove pipe to the chimney?

The thimble connects the stove pipe to the chimney.

How long does it take for a chimney pipe to dry?

Allow it to dry for 24 hours before attaching a stove pipe.

What is a thimble in a wall?

A wall thimble serves the same purpose as a ceiling support box except it is used when going through a wall. At the wall thimble is again where you would convert from the black inside stove pipe to Class A chimney pipe. The wall thimble is not a support point itself but the Tee and the Tee Support that connects to the pipe running through the wall thimble is. The Tee is just that, a pipe in the shape of a “T” with all three ends open. The snout of the Tee is where you will connect it to the pipe passing through the wall thimble. Then you will connect a clean out cap to the bottom of the Tee once it has been secured in the Tee Support Bracket. The Tee and the Tee Support Bracket will bare all of the weight from the vertical pipe outside of the building.

What is Class A Chimney Pipe?

You may hear Class A chimney pipe referred to a few different names such as double wall chimney pipe, triple wall chimney pipe, all fuel chimney pipe, or insulated chimney pipe. No matter what someone refers to it as it all serves the same purpose: to vent an appliance that burns wood, coal, or oil to which the exhaust gases reach very high temperatures. Wood burning appliances are the most common type of heating appliance that will require Class A chimney pipe for its venting system. Others heating appliances that could require Class A chimney pipe are boilers, stoves, pre-fab fireplaces, or oil burning furnaces. Class A chimney pipe usually has a UL-listing, which allows it to be used with a wider variety of manufacturer’s stoves, fireplaces, etc. The majority of brands have an inner layer constructed of stainless steel but the out layer can be either stainless steel or galvanized steel. Any components that will be exposed to the elements should be stainless steel so it will not rust. Galvanized steel will show signs of rust over time and eventually wear through needing to be replaced sooner.

Why do you need an elbow kit for a Class A chimney?

An elbow kit will be necessary if you have an obstruction to maneuver the Class A chimney around such as an eave on the side of the house or trusses/beams in the attic space. The most common obstruction is getting around an eave when venting through the wall and the Class A chimney pipe runs up the outside of the home.

What type of shield is needed for a Class A chimney?

There are 3 types of protective shields that you may need for your Class A Chimney installation. The first one is the Attic Insulation Shield . This is the most commonly used shield. It is installed above the ceiling support box to keep the insulation and other materials away from the Class A pipe. The second type is a Firestop Radiation Shield. It is required when passing through a ceiling or flooring where a support box is not present. This protective shield is most commonly used in installations where the Class A chimney will be passing through multi-levels or running through a chaise. The third protective shield is going to be the Roof Radiation Shield. This shield is installed when the chimney pipe is enclosed at the roof exit point. These shields are not as commonly needed as the attic insulation shield and the firestop radiation shield.

How does a storm collar work?

Then storm collar is them installed over the pipe and secured to the top of the roof flashing with a bead of silicone. The storm collar covers the space between the flashing opening and the chimney pipe.

What is the phone number for Class A chimney?

However if you still have questions or did not find the component in question in this article please give our knowledgeable Customer Service Team a call at 1-866-667-8454.

Can you use more than one chimney pipe brand?

However they all have the same basic components. Each of the brands have specific types of connections making each component brand specific, meaning that you cannot use components from more than one brand and have them be compatible.

How thick is a chimney block?

4 inches of cement (the thickness of a chimney block wall) is the minimum required around (and between) flue liners, so using firebrick and refractory mortar (due to contact of flue gasses) of that thickness would suffice solid fuel codes. (oil is NFPA 31) I'm not a chimney expert in the business like bholler, so he may know if that 4 inch spec comes from the International Building Code, or Mechanical Code which is intertwined with all the other International Codes.

Can you have more than one chimney breach?

The problem is that you are not allowed to have more than one breach in the chimney. Now that one breach can be a thimble and cleanout but you cannot have a second thimble. Your inspector has already told you that your chimney expert was incorrect.