Here is all you need to know about a chimney thimble, it’s usefulness, installing one, and sealing off an unused or damaged unit.

One of the many causes of chimney related fires is the absence of air space between combustible materials and vent pipes. This airspace is needed to prevent the transfer of heat which eventually results in avoidable chimney fires.

About Chimney Thimble

If you wish to install a wood stove or replace an insert, you’ll need to have a thimble installed on your walls. You’ll normally find thimbles installed in brick or stone chimneys at a height of 5 feet above the ground.

This is installed at a 90-degree angle and serves the important function of accommodating the stove pipe.

Have A Thimble Installed No Matter the Heating Appliance

Different types of heating appliances are used in homes.

The major differences between these heating appliances or stoves are seen in the fuels used. Common heating fuels include wood, pellets, burning gas, and Liquid. Irrespective of the fuel used in your stove, a thimble will prove useful.

This important component is insulated and prevents the transfer of heat to combustible material.

As such, it’s a safety measure you need to put in place. The thimble also serves as a safe passageway for connecting heating appliances both in and out of masonry chimneys.

Now that you know, your heating devices must be properly installed. Over time, you’d have saved yourself a lot of maintenance costs especially those relating to chimney fires.

Be Wary Of Thimble Ports

Thimble ports are great insulation mechanisms that safeguard your chimney.

However, this depends on the condition of such thimble ports. Thimble holes that have been left unused for a significant period of time are likely to result in fire hazards. How so?

When stove pipes that usually pass through thimble ports are removed, and the space left for a long time, it results in problems. Here, a pileup of creosote occurs in such thimble ports.

It’s no news that creosotes easily ignite when not cleared frequently.

Several cases of chimney fires have been due to abandoned thimble ports being ignored while the chimney is still in use. Chimney fires are only a part of the problem.

The other is an issue of leaking flue gases. These are situations you want to prevent from happening.

Closing Off An Unused Or Abandoned Thimble Port

The best way to prevent an impending disaster is to prepare for it.

Here, the thimble ports left open will need to be sealed before using the chimney. This is meant to limit the buildup of creosote as well as gas leakages.

Brick and mortar are among the best materials to seal off such openings or ports. Sealing off the thimble ports alone won’t be enough. You’ll also need to have them covered with flue.

In other words, a flue lining installation will be necessary. You need a flue lining to prevent overheating of the pie-plate or covering.

Installing A Chimney Thimble

When installing a chimney thimble, you’ll need to be careful to avoid damage to the interior chimney flue. If you plan on doing this task yourself, you’ll need some basic tools and supplies.

Such tools and supplies include masonry drill, carpenter’s pencil, trowel as well as mortar.

Others include a small sledgehammer and chisel. With these, you should be ready for business. Installation steps include laying out the entry area, chipping out the brick within your markings, and carefully cutting the flue inside the chimney.

Other steps include applying mortar to the interior, positioning your thimble, filling all gaps on the inside, and lastly filling all gaps on the Outside.

Let’s further discuss these points briefly.

  • Laying Out the Entry Area

You’ll need your carpenter’s pencil for this task. The thimble needs to enter into the wall.

As such, markings will need to be made on the brick for chiseling. You’ll need to draw the entry area before proceeding to the next stage.

  • Chipping Out the Brick Within your Markings

Having marked out your entry point or area, you’ll need to chisel out the marked area over the brick. Tools needed include the small sledgehammer and chisel.

An alternative tool to use is the masonry drill. Whatever tool you use for this task, ensure you’re comfortable using it.

  • Carefully Cutting the Flue Inside the Chimney

As you chip through or drill around your markings, you’ll encounter the flue. The side of the flue should be cut properly to align with the cut or hole being created.

  • Applying Mortar to the Interior

Now, your mortar needs to be applied to the face of the cut hole. It’s necessary to cover all areas of the interior clay flue as well as the brick with your mortar. A trowel should enable you to perform a neat job.

If this seems like a lot to you, consider calling for help.

  • Positioning your Thimble

Having prepared the space for your chimney thimble to sit, carefully place it into the hole. Put your hands through the port to feel the joints between the thimble end and the flue. These should be flush and without any spaces.

Now, add some more mortar around the thimble and press using your trowel while stabilizing or holding the thimble with the other hand.

  • Filling All Gaps on the Inside

Ensure that there are no gaps on the inside. The inside refers to the inside edge of the thimble and the inside face of the clay flue. This shouldn’t be rushed at all. Your hands should fee around the edges to ensure there are no gaps.

Any gaps felt should be filled with mortar.

  • Filling All Gaps on the Outside

Just like the inside, gaps on the outside surface should be filled as well. This is the part that can be easily observed.

Having successfully filled all gaps, a good dressing will be necessary. The surface should be smoothened. Here, any mortar should between the thimble and brick is smoothened with the trowel.

Call An Expert For Thimble Task

An expert will perform this chimney installation task much easier. Here, you don’t have to stress yourself at all.

Information is key to all human endeavors. This applies to thimble installation and maintenance.

Here, we’ve covered important details on chimney thimble, precautions as well, what they’re used for and how to install them.

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