Hollow fireplace/metal firebox

[MNFireplace]

Hi everyone. I bought a house a few years back and have a very odd fireplace that I'm hoping someone can help with. The shell of the fireplace is fieldstone and mortar. It's about 5' wide at the base and tapers after it gets above the firebox. Where this gets weird is that the fieldstone "shell" is hollow inside. The foundation of the shell is on cement block that goes down to the foundation in the basement. The firebox that I see from the living room is metal, and rusted to the point I'm scared to use it, because... The foundation under the fieldstone shell is hollow as well, and my well water pump and pressure tank are below the firebox. There's a door in the basement that opens to this small room for access to the pump, and I can look up and see the firebox. It appears that there may have been a fan in there previously that would have circulated air. But the whole thing is so rusted and corroded from water coming down the chimney, it's hard to tell.

So here's my question... Has anyone ever seen/heard of a fireplace like this before? I've contacted a few local places and described it and they don't want to touch it. We had a chimney sweep out when we first bought the house and he said he'd never seen something like this before either. We'd really like to keep it as a wood burner, but I'm thinking our only option may be to convert to gas, if I can find someone willing to customize an insert. Anyone have any ideas?

Thanks!

 

[bholler]

It is pretty common It is called a heatform. We cut out a few a year and build a masonry box inside the shell

 

[tgdontap]

It is pretty common It is called a heatform. We cut out a few a year and build a masonry box inside the shell

Rather than start my own thread I'm going to piggyback on this because we have essentially the same setup. bholler, when you cut out metal heatform boxes have you found any structural issues with masonry around the box? I've considered cutting ours out but I've read comments somewhere that made me a little nervous about that. Is it possible that the flue tile or any structural elements of the chimney could use the metal box as a support? It seems improbable to me but I can't find any reliable details on how these things were put in.

 

[bholler]

Is it possible that the flue tile or any structural elements of the chimney could use the metal box as a support? It seems improbable to me but I can't find any reliable details on how these things were put in.

yes it is possible i have only seen one where the box supported the clay liners most liners are supported by masonry.