What fireplace was it? I just like to keep track of the ones that allow inserts for my own knowledge. I know a couple heatilators do.
@bholler , here's what I referenced from the osborn/drolet manuals when I was shopping for inserts to go in my heatilator--my setup seemed to satisfy the requirements:
"2. INSTALLATION INTO AN EXISTING FACTORY-BUILT ZERO-CLEARANCE
FIREPLACE: It is possible to install a wood insert into an existing factory-built zero-clearance fireplace.
However, there currently exists no UL or ULC standard specific to that type of installation. The first thing
that must be verified is that the factory-built zero clearance fireplace is listed (it must be certified by a
competent certification body such as Omni or Warnock Hersey). It must be suitable for use with solid fuel
and nothing in the owner’s manual must specifically prohibit the installation of a fireplace insert. When in
doubt, check with the fireplace manufacturer. The installation of the zero-clearance fireplace MUST be
thoroughly inspected by a professional in order to ensure that it still meets the manufacturer’s specs and
code conformity. The chimney must be of at least 1" (25 mm) larger in diameter to accommodate a
required continuous stainless steel liner running from the flue collar to the top of the chimney termination.
Never remove parts that serve to insulate the zero-clearance fireplace from combustible material. Only
readily detachable parts that are easily replaced, such as damper parts, screens, and doors, are to be
removed from the fireplace. These parts must be stored nearby and available for retrofit if the insert is
ever removed. Removal of any parts which render the fireplace unfit for use with solid fuel requires the
fireplace to be permanently labelled by the installer as being no longer suitable for solid fuel until the
removed parts are replaced and the fireplace is restored to its original certified condition. Furthermore, any
air vents, grilles, or louvers that serve to create an air circulation pattern around and outside the zero-
clearance fireplace shall never be removed."