Avalon Pendleton Fire Box inside a Superior Fireplace?

Hello forum! My first post, and as a rank amateur I'm not even sure my thread title contains the proper terminology so I apologize in advance!

We have just purchased a home in Eagle River Alaska, and it appears I have a project on my hands. As you can see (pic), the glass is cracked. It just happened, and it was due to my St. Bernard and my pre-teen son having a wrestling match too close to the fireplace. The crack may be a blessing in disguise though because it prompted further investigation into the unit.

Bottom line: heat output is pathetic.

We have a fair amount of nicely seasoned and split birch firewood, and we have built a few fairly hot fires. But even at it's hottest, one has to stand no more than 2 feet away to feel any heat at all. After burning well for 8+ hours, the temperature only marginally changes in our medium sized living room on a 45 degree day. Additionally, the "blower" is completely useless. It is located in the grated space below the Avalon firebox. I have just found that this space is completely sealed from the rest of the firebox so air simply circulates in that small lower area and goes nowhere.

From my amateur perspective, it appears that they inserted an Avalon fire box into an insulated Superior Insert, so nearly all the heat generated just exits through the top somehow. It looks like the Superior insert was designed to have a (gas?) fire built directly in it but now it has been re-purposed (much metal has been inexpertly hacked out to make the Avalon fit) for the Avalon Pendleton fire box.

So my question is, how do I make this setup work right?

Is there some way to circulate air through the bottom of the insert and out into the room? I want to do this correctly, so if it involves tearing out the existing mess completely then that is what we will do. It is not apparent from the picture but the fire box actually looks pretty nice when everything is put together. So if I can retain the same "look", I'd like to but safety and efficiency are the first 2 priorities

Thanks for reading my long first post!!

Daksy, thank you so much for the reply! I will definitely take your advice and research the insert for safety's sake.

The receipt for the original install actually survived to reach me. It was done back around 2000. The installer (North Country Stoves) is still in business. I wonder if they should be held liable for this mess. The home has been through several owners (and 2 renters) since then and my guess is none of them bothered to research why there was so little heat output.

I'll update this thread as I go through this process. Thanks again!!

Just wanted to post a quick update to my original issue...

It looks like we managed to resolve it completely. I may not be using the correct terminology but the problem was the amount of ventilation in the original fireplace. Not only were there the vents across the bottom shown in the picture, there was another set I neglected to include in my photo that ran across the top. While the top section is normally out of view when the cladding is in place, it is still virtually open to ventilation.

Using foil and metal tape, we sealed off all the vents & other openings on the fireplace. Now the insert is working very well and keeping the whole top floor of the house nice and cozy.

I plan to find an inexpensive (and safe!) way to push air through the insert vents without buying the $370 fan that goes with it but I may start another thread for that topic

Thanks everyone for the input!