In professional terms the INSERT is a fireplace unit that fits inside of an existing wood burning fireplace, whether prefabricated or masonry. An INSERT basically "inserts" into the existing fireplace. The INSERT is smaller but has a large clearance to combustibles, requiring the already present safety clearances of the existing wood burning fireplace. An INSERT can be gas, wood and pellet burning. An INSERT is not safe to install on it's own, with one exception, some pellet units are tested and UL listed to be installed with an additional shroud from the manufacturer, and occasionally are ZERO CLEARANCE.
The ZERO CLEARANCE is a pre-manufacured fireplace that has an extra shroud built on it that reduces the clearance to combustibles (floor underneath is zero clearance- it can sit on wood and be safe) and typically quite minimal to sides of the fireplace unit. These units are unable to be INSERTS. These units are mostly gas and wood burning.
It is ALWAYS best to read the whole installation manual before purchase and if you have further questions, call and ask a professional or contact the manufacturer.
This can be a tricky question! It depends on the manufacturer, the fireplace, stove or insert, the place you want it installed and the fuel type. It is always best to consult the installation manual, manufacturer or professional for what the best practice is for that particular unit before you buy, to be sure you are able to vent it out safely and properly. Each unit may vary, even within the same brand.
Wood Insert: Requires a stainless steel (aluminum will melt) chimney liner through the chimney. There is debate as to how far into the chimney, we always line the chimney to the top- this reduces drafts as well as draw issues. Older models were less efficient and technology was not as advanced as current models, and the days of just inserting the unit without a chimney liner are over.
Gas Insert:There are a couple different lining configurations for direct vent gas inserts. Our preferred way is to line the existing and up to code chimney all the way up for both intake and exhaust. Gas B-vent inserts use a single liner for exhaust, we would line to the top of the chimney with this type as well, however we do prefer to use direct vent inserts for better efficiency.
Pellet Insert: We prefer to line with a bioflex liner to the top of the chimney. Depending on the unit and manufacturer's instructions, it is possible to vent straight through the chimney. If the pellet insert is UL listed as being able to be "built in" as a zero clearance fireplace, with or without a special shroud, you can vent through the wall, up and out the wall or all the way up through the ceiling.
Gas B-Vent Stove: Requires special gas venting straight up through the roof, or up through an existing chimney that is not used for anything else. This is not ideal for basement installations, unless there is an existing chimney.
Gas Direct Vent Stove: Requires special direct vent gas venting. This can be vented in several different ways. In fact it can be vented in more ways than I will even describe.
Wood pre-manufacturered zero clearance Fireplace, open or sealed combustion:
Gas B-Vent or Gas Natural Vent Zero Clearance fireplace