Safety Considerations for Fireplace Inserts

Safety Considerations for Fireplace Inserts

Fireplace insert season has arrived! Fireplace inserts are magical machines that transform cold, drafty fireplaces into sources of warmth and beauty, fostering priceless family togetherness. You don’t need to spend a king’s ransom, but you do need to do your homework. Wood-, pellet- and gas-burning inserts create more heat than a traditional fireplace (that is the point, after all), so it naturally follows that the requirements for mantel heights and floor protection are more stringent than for a traditional fireplace. As a consumer, you can either study the applicable codes, standards and manufacturer specifications to make sure your installation adheres to all the requirements, or utilize Enchanted Fireside’s exclusive HearthMatch system to guarantee that your insert will not only fit inside your fireplace but will meet all the safety criteria as well.

Each fireplace insert has its own safety criteria, established by the manufacturers’ testing lab (the biggest testing lab companies in the hearth industry are Omni & Warnock Hersey). The labs ensure the inserts meet UL (wood burning), ASTM (pellet burning) or ANSI (gas burning) standards, and for each model tested, identify how far away combustible materials (e.g., wood mantels, and wood, carpeted, or linoleum floors) must be from the insert to avoid being a fire hazard. The results of their testing go into the installation manuals, with most of the model-specific testing results described in the – usually titled – “Clearances to Combustibles” section.

Clearance to Combustible requirements should be straightforward, but in our experience, are frequently misinterpreted. For example, test results often allow mantel “trim” – the breastplate of wood above the fireplace – to be closer to the insert than the deeper mantel shelf above. However, the wood breastplate is only considered “trim” if it is 1 1/2″ thick or less (unless the manual specifically sets a different threshold). Any wood deeper than the trim threshold must follow the more stringent clearance requirements for mantel shelves. Shields (such as mantel protectors) may only reduce these clearance requirements if specifically allowed in the manual. And, unless the manual specifies otherwise (based on testing), mantel protectors cannot reduce clearances to less than 18″ above the heat surface of the insert.

Side trim may be up to 1 1/2″ thick (unless the manual sets a different threshold); any mantel leg deeper than that must meet clearances as if it were a side wall. Floor protection may be required to meet thermal resistance requirements, and those requirements may vary based on the height of the fireplace opening above the floor.

Manufacturers spend tens of thousands of dollars for each model they produce to be tested. It is in their best interest to have the required clearances be as low as possible, because that will enable their insert to be installed in more fireplaces. They have a lot of leeway: the wall above a fireplace is allowed to be 117 degrees warmer than ambient room temperature. In a 70-degree room, that means the wall may get up to 187 degrees, and still be considered safe (even though it may be too hot to touch). If the testing determines that the mantel must be 24″ above the fireplace to avoid getting hotter than 187 degrees, then you can only imagine how hot the wood will be if it is closer than the 24″. That would be a fire hazard.

If you have read this far, wow – thanks! Now you know more about fireplace insert installation safety than many in this industry. Unfortunately, status quo in the hearth industry is “buyer beware” – where it’s up to the buyer to understand and apply relevant building codes as well as the manufacturer’s instructions when making a purchase decision.

We are more like “buyer, let’s make sure your installation can be done safely.” Our HearthMatch system instantly analyzes 24 measurements of your fireplace in comparison to the current specs of every insert (what did you do over your summer vacation? 😉) – including some models that we don’t even sell. HearthMatch quickly helps us rule out inserts that don’t fit and identify what will fit safely. Maybe you are planning to take down your mantel anyway or redo the floor around your fireplace. Whatever you choose, we want you to know what is required for a safe installation before you give the final approval to install your new insert.

We also dedicate time and resources as certified speakers for the hearth industry to educate our local building officials on how to interpret the manufacturers’ requirements. Our hope is that one day, the inspectors will check every one of the installation criteria, every time, so that you will know you have a safe installation. In the meantime, at least we know WE have checked them all for you.

Ready to get started? Bring in the 24 measurements on our crazy complicated HearthMatch fireplace measurement sheet, along with a few photos of your fireplace, house and chimney (on your phone is fine). Whether you plan to DIY or DIWU (do it with us 😉), we can help identify your most likely best options for inserts and get you on the path to being “Warm & Happy.” Looking forward to seeing you soon!