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There are lots of reasons a homeowner might wish to add an insert to their prefabricated fireplace. For one, fireplace inserts are known for their heightened efficiency, so more heat and less energy costs may be a goal for some. Adding an insert can also be an option when looking to switch up fuel types. Or maybe you just want a new style, and this seems like the best route.

Regardless of the reason, there are a few things you’ll need to keep in mind before moving forward. Count on the team at The Chimney Doctor to help you out every step up of the way. Our CSIA-certified sweeps can guarantee you stay safer and more comfortable while navigating all of your chimney and fireplace-related needs.

Test Standards & Clearances Often Get Altered

Every prefabricated fireplace has standards and clearances that must be met to ensure the safety of the homeowner. The addition of a fireplace insert with drastically different heating characteristics can alter these clearances and potentially change the heat signature of the entire appliance and venting system. In these cases, the appliance will overheat and any surrounding woodwork or flammable materials could ignite.

Many wonder if we could add the insert, then perform new tests to ensure everything is okay. Unfortunately, this isn’t an option either. There are currently no standards from the Underwriters Laboratory (UL) for testing this type of set-up though beginning at the end of 2021 discussions began at the request of a fire investigator from Ohio who has seen hundreds of fires related to inserts in factory built fireplaces over the past several decades.

There is often confusion surrounding the codes, standards, listings (tests), and manufacturer instructions as they relate to these types of installations. For more information on the specific codes, standards and potential issues if you are considering this type of an installation please read this document that our owner put together for the task group formed by Underwriters Laboratory (UL) to explore this specific issue.

Download: Current Issues with Solid-Fuel Inserts in Factory Built Fireplaces and Chimneys

Remember – just because a manufacturer says their insert is approved for installation into a factory built fireplace it doesn’t mean it has actually been tested. Currently there is no standardized test to allow this type of installation.

In general appliances not listed as a part of the original factory built fireplace should not be installed. They are considered an aftermarket part and may alter the heat signature of the appliance.

In the end, most prefabricated or factory-built fireplaces don’t allow inserts to be installed into their systems. Some specifically preclude the option. And many older models won’t even have language regarding inserts in their manuals at all.

Fireplaces & Inserts are Tested With Different Standards

Another important factor to keep in mind is just how these units are tested. The UL tests their prefabricated fireplaces and factory-built inserts separately, and each system must pass a wide range of tests to get approved. Stoves and inserts are only tested as freestanding room heaters. They are currently not inserted into a fireplace as part of any UL test. This means your fireplace and insert go through different testing processes, and just because a certain test was successful with the fireplace doesn’t mean it will be successful with the insert installed. In the end, assuming your insert will be fine just because your fireplace fairs okay isn’t going to be a viable option.

Essentially, because there is so much variety when testing both prefabricated fireplaces and factory-built inserts, it is hard to guarantee combining any two would produce good or safe results unless they were specifically tested together.

Here’s what we suggest – rather than install an insert, remove the prefabricated unit altogether, then install a high-efficiency wood or gas fireplace instead. In this way we can be sure that it meets and exceeds all minimum requirements and continue to put your safety and peace of mind first in all that we do.

A Lot of Factors Simply Don’t Add Up

In the end, when it comes to installing an insert into a prefabricated system, there are many things that simply don’t add up with and that insert manufacturers aren’t able to provide clear answers for. A few examples of some common issues are outlined below.

For example, approving the addition of a 300-500 pound insert into a prefabricated unit that should only hold up to 110 pounds of wood doesn’t make sense. The math simply doesn’t add up and over time that additional weight can start to crush the sheet metal supports beneath the fireplace and overheat combustibles beneath the system.

Along with this, some inserts that are “approved” for installation into a prefabricated fireplaces want high temp or HT tests be performed and passed by the chimney systems through which they run. Many of the factory built fireplaces found in homes today were never tested to the HT standard, especially if they are older. For example, if the fireplace was manufactured before 1993, there wasn’t even an HT test at all. After 1993 the HT test was optional. As such any insert manufacturer wanting a chimney system that was tested to the higher HT standard should not be installed or the system could overheat surrounding combustibles even if clearances were maintained. Then again, given that liners are also not tested in chimney piping systems in either the liner tests (UL1777) or the piping tests (UL103 or UL127) by UL this is a moot point.

In the end, it is important to remember that there are no standardized testing criteria when it comes to installing an insert into a factory-built fireplace. In fact, there is currently no way to even formulate a test to approve this process. There are just too many brands, variations, design types, and variables. Underwriters Laboratory is currently working on this project to see if its possible but it is anticipated that this may take years if possible at all.

Our Policy

While other hearth dealers may install inserts into factory-built fireplaces, this is a service we have chosen NOT to offer. There are simply too many safety risks associated with combining two systems that don’t meet all of the requirements of the manufacturers involved, or for which testing data is not available. We feel that doing so would jeopardize the safety of our customers.

What We Can Offer Instead

Like we’ve mentioned, removing your entire prefabricated unit is always the better option if you’re looking to upgrade. When replacing a fireplace this often allows us to address other issues that may not be readily apparent: cold air down drafts, rotted wood in old chases, missing insulation, improper firestops and fire blocking, or old outdated finishing materials used around your fireplace. Working with us you will end up with a system that is functional, efficient, and suitable for continued use day in and day out.

In the end, if you want to work with professionals who care about your safety first and foremost in all they do – that’s where our team is qualified and excited to help! We install fireplaces, stoves, inserts (where suitable), and factory-built fireplaces, so we know the ins and outs of installation. Whether you are interested in wood, gas, pellet, or even the newer electric options, we can help.

When it comes to building a fire inside of your home, staying safe and installing products within the bounds of how they were tested should always be the number one priority. Don’t take any chances – rely on our experienced and educated crew to provide you with the high-quality level of care you deserve.

Call us at 970-234-3330 today to get started!