A "fireplace insert" is a plate steel or cast iron wood burning fireplace box with glass doors that is inserted into an existing masonry fireplace.

The Saber wood burning fireplace that you have linked is a "zero clearance factory-built" sheet metal fireplace (as defined by UL 127) that is sometimes inaccurately called a "zero clearance fireplace insert" by retailers but not by the manufacturers.

The Saber fireplace is a good looking one but it is essentially a copy of the better known Lennox Colonial 36 although it does offer firebox openings wider then 36" but, unfortunately, the opening heights are all limited to 30" in height.

Here is a link that might be useful: fireplace insert

macv - sorry for the confusion. The builder has been calling the prefab thingy an insert & I just got the terminology messed up. If we're doing new construction, he certainly isn't building a masonry fireplace and then putting a real insert, as defined by the link, into it.

Do you think that the proportions get out of whack when you go from 36"x30" to 42"x30"? This is for the "cozy" great room (16' along fireplace wall by 18' wide w/ 10' ceilings) so it is mostly when we have guests there for ambiance. (DH & I will spend most of our time in the keeping room with a direct vent gas stove if we want fire.) I know a 42" firebox is what is expected, but I want the right proportions.

Here in Houston, where a fireplace is passively ornamental (mostly) - some folks just put their flatscreens in front of the fireplace opening if they don't want to mount them above the fireplace, since they never use the fireplace - I've gotten use to seeing the 42"x30" and I'm not sure if I've just been conditioned to ignore something that is "off".

Thanks for clearing things up - Jo Ann

P.S. I guess I got over excited when I posted because its been a tiring few days trying to get the last details of the contract right. DH was so enthusiastic when he found the Saber & I wanted to share.

IMHO the maximum width for a traditional zero clearance fireplace is 36" assuming the height is 29 to 30 inches. If you want a "modern" fireplace the more rectangular (wide) ones are fine.

I went with a pre-fab steel unit in new construction because I don't trust the contractor to build it right as far as the doors, damper, flue, draft. I'm outside San Antonio and I used mine alot this winter. It's like 41W and 24 H. If you go with doors I highly recommend frameless doors, you see all the action, but mine are usually open so I can heat my whole 1300 sf with the furnace turned off. pic...

Here is a link that might be useful: {{gwi:1406707}}