Looking for some guidance on fireplace

[hardboiledeggs]

Hello. Calling for help from Saskatchewan Canada. I have a house from the 50s with an absolute unit of a masonry fireplace. The whole unit is 17 wide by 17 tall by 4 thick of field stone.
Chimney is the wall of the corner of the house and has one inside fireplace and one outside. Currently the inside fireplace is a regular open fireplace with glass doors. Unit also has some convection Vents that seem to run behind the fire backing and to the other side Vents. Also has what I believe is an outside air vent that goes outside and comes up under the firebox.
Damper in the chimney is gone so cold air and wind blast down in the winter so I'm looking at upgrading to a modern unit. Current firebox is 48 at the front 44 at the back 29high and 24 deep.
Was looking into inserts but can't find anything that I really like. Want to maximize width and have double doors. I know I likely will have to cut some of the stone to expand the opening vertically but I have a masonry saw and am not intimidated by that. Been doing some digging and saw a few units that intrigue me.
Osburn horizon
Superior fireplace wct2042
Rsf focus sbr (single door but width works)

Can anyone tell me if I'm on the right track or totally out to lunch?
Don't need it as a primary heat source but would be use regularly in the winter.
Let me know, thank you!

 

[all night moe]

It's beautiful but, that's a HUGE heat dump into the great outdoors. Especially with your climate, I'd want that gone.

 

[bigealta]

If it was my house i'd try to get a free standing woodstove in there. But that's what i like.

 

[EbS-P]

You want to be shopping for wood burning inserts not zero clearance fireplaces or a free standing stove. You will be required to run a full SS liner. Insulate behind and around the insert add a block off plate and insulate above it.

I don’t know of any double door inserts. That’s a big opening. It at 29” high your stove choices will be limited. Check Osborn Pacific energy, for inserts. Maybe a jotul F55 with short legs.

 

[begreen]

I would install a large wood insert in there with an insulated, 6" stainless liner. There should be an insulated block-off plate and I would insulate behind the insert if possible. The insert will have a single door, but that is actually a good thing. They usually seal better.

 

[dvd1217]

I would install a large wood insert in there with an insulated, 6" stainless liner. There should be an insulated block-off plate and I would insulate behind the insert if possible. The insert will have a single door, but that is actually a good thing. They usually seal better.

Curious why insulate behind insert? Would that actually retain a lot more efficiency?

 

[begreen]

It's to keep more of the heat generated in the room. Otherwise a significant portion is radiated outside. A FLIR camera illustrates this pretty dramatically.

 

[dvd1217]

To be clear you are saying insulate the 3 walls of chimney where insert will be as well as block off plate. I guess it’s anecdotal but how much more heat does one gain from that? How much clearance would be suitable?

 

[begreen]

Anything will help. How much will depend on how much insulation value is in place. Typically 1" Micore or Roxul board are used. The heat gain is significant and notable.

PS: no insulation on top of the insert, however.

 

[hardboiledeggs]

pretty well have myself sold on a osburn horizon now. going to pull the old firebacking out and cut the stone above to fit the thing in there. have a couple questions for set up though.
the two vents on the side of the fireplace are connected by a square tube behind the firebacking and im going to have to cut that out but im wondering if it lines up close enough if i could knock out the gravity vents on the unit and leave it unhooked and just let the heat naturally find its way out of the vents or is that a recipe for disaster?
also wondering on outside air kit. currenly it has outdoor air drawing from beneath the fireplace is that useable in any capcity with this new unit or is it worth it to drill a hole for an oak?