Confusion identifying fireplace type and options to add insert/stove

[AHems]

Hi there,

First post and a total newbie, so go easy on me!

I've read a ton of really useful info on here and THINK I have what my be a candidate for adding in an insert, but I notice some differences between the other heatform style units and my own (mainly the lack of circulation tubes on mine, though it does have some sort of venting/circulation areas in the usual lower side and upper middle that do seem to function). Is anyone able to help me try and determine what I actually have here? I've had people say its a heatform style unit and could easily be updated by cutting and adding an insert and SS liner, but then I've also had someone tell me this is prefab zero clearance unit that is not able to handle an insert.

There do seem to be some water/rust stains, which i can only assume is from a time before a concrete cap was put on as I've seen a ton of rain here since i moved in and zero signs of any moisture . There is a fair bit of rust all over, but everything seems to feel pretty solid to me with no holes or weak spots.

Truthfully, I'm completely confused between heatform and zc and am none the wiser as to ways to move forward. I do have a sweep coming next week to give everything a once over and to determine my options regarding inserts and if Im safe to use as an open fireplace in the meantime, but I would appreciate any thoughts anyone may have on both what it is likely to be and if it seems safe enough to use for this season whilst I save for an insert and remove/replace the granite stonework.

The house is a 1980s rancher on Vancouver Island, BC. There is another clay lined flue on the other side of the wall that was used for an old cookstove, which has since been removed.

 

[EbS-P]

It appears to me to be a metal heat form/heatalator venting through a tile lined masonry chimney. It is possible to install an insert with liner. Some of the metal may need to be cut out to accommodate the liner, that’s normal.