Is running two back-to-back wood inserts crazy/dangerous?

[jaylude]

Hoping to tap into the collective knowledge here and get some opinions/recommendations/cautions on my somewhat unique project. I'm looking to add, at minimum, a wood burning insert into our beautiful double sided, center-of-room masonry fireplace. Currently, it just has a freestanding propane gas log setup. Super inefficient and way undersized for this large fireplace. I want to produce some heat to supplement our existing hydroair forced air system, while ending up with an aesthetically pleasing & functional setup. Here's a pic of the two opposing sides of the fireplace, and the relevant dimensions of the masonry. Also of note, the interior dimension of the flue appear to be 16" x 18" so there's actually plenty of room to run two 6" liners up and out if I wanted to.



I'm pretty set on a Blaze King Ashford 25 as the wood insert. What I'm stuck on is as follows...do I want to just KISS and put a single wood insert in while just blocking off the second side of the fireplace, or should I lean into the double sided-ness and go with something more unique with two back-to-back inserts? I mean, I've already got propane piped to this location, and there's plenty of depth (38" depth) for two full inserts of some type. And if I do go with something like a large wood insert back-to-back with a smaller wood insert, or a wood insert back-to-back with a propane insert, what are the big drawbacks (outside of price...) that I'm not thinking of, safety or performance wise?

Here are my couple of ideas:

1. Medium wood insert (BK Ashford 25) back-to-back with a smaller wood insert, something like a small Regency Alterra non-cat. I've got the depth (15-1/8" for the Regency Alterra + 18 for the BK Ashford 25) but what problems, if any, will this cause with just 6-ish inches between the two backsides? Do I need to put a cement board or similar between the two? Am I setting myself up for drafting or performance issues, or safety issues with the units themselves arranged like this?

2. Medium wood insert (BK Ashford 25) back-to-back with a propane insert. Is this a safety problem, due to the presence of the propane feed line in proximity to the radiant heat of a wood insert? Could I insulate and prevent that from being an issue? I really have no idea on this, but I love the idea of a wood burning insert on one side for the heat output, and an instant decorative flame on the other for ambience when occasionally sitting down to watch a movie. School me on if or why this is a bad idea.

3. Medium wood insert (BK Ashford 25) on one side, while blocking off the other side directly behind the insert and just using this second opening for wood storage. I do like the idea of having a big old 18" D x 34"W x 28" H area to store wood in proximity to the insert, but if I do this, how much insulation and what type would you use to make sure the wood doesn't get too hot and potentially become a fire hazard? I have no feel for this. Use cement board, and some mortared brickwork? What would you professionals do?

Is there a better idea I haven't thought of?! Think big and outside the box. Appreciate any input

Some more pics in case they help:

 

[kborndale]

I don't think two inserts back to back could work. They would each need their own flue and I would think they would cause each other to overheat. Unfortunately while double sided fireplaces look very nice, they don't work very well in reality.

 

[Plynwfire]

Even though you have sufficient space to get 2 -6'' liner systems down the clay tile. There are a few issues you will run into. 1. Each flue system will need its own chimney cap. When sealing off the clay tile you need what is called a top plate and a top plate frame. This is what sits on top of the clay tile and seals off the tile from rain, animals etc. etc. Each liner system uses one of these. They do not make a double hole top plate per se. Also you have distances that must be maintained center of flue to center of flue where the termination occurs when exiting the chase. You will not have said clearances. Had that fireplace had 2 clay tiles and they were set apart from one another on the top of the chase, then it would be a different story, You would utilize each tile for 1 liner system on each insert. Anything that you do would really be a rigged up system and not to code.

 

[loondip]

We have a double sided fireplace and installed a BK Princess insert on one side. Our setup is not in the center of the room like yours -- we have one side in the family room and the other side in our dining area.

I thought I would want to brick up the back side (dining area), but we get some heat off the back that helps warm up the dining area. Our fireplace had doors on both side -- I left the doors on the back side, but open it up when we're burning to allow more heat into the dining room.

Since your setup is all in one room and does not appear to have doors, you might consider something like a fireplace screen on the back side to allow heat to come into the room while still blocking the visual of the back of the stove. I feel like this would be an inexpensive thing to try while you decide if you want to block it off completely etc. I don't know what the code is regarding an exposed rear of stove is -- it may need to be covered by more than a fireplace screen, in which case maybe a piece of perforated or decorative metal sheeting that is screwed into the brick might work.

I would probably not store wood back there unless is it securely blocked with cement board/brick, etc.

We love our BK! I think an Ashford would look great in your space. Here are pictures of our setup:

 

[EbS-P]

I’d be looking to see info could fit a Jotul F55 in there. F45 if any are still in stock. f500 last resort. I don’t like the Princess here because it sticks out so far. Still kinda like that look through space since it’s a raised hearth.

Honestly I’d really be looking into another location for a freestanding stove. 30 series BK a s maybe glass doors for a a few fires per year in the double sided gas fireplace fireplace.

 

[begreen]

Can you afford back to back inserts? If not, I would just put in the BK and put a black grille in the opposite side made of expanded or perforated metal with a blockoff plate in the damper area.

 

[jaylude]

Thanks everyone for the input so far.

I'm embarrassed to say that I didn't quite grasp that the typical flue & clay liner on a masonry chimney with two appliances were separated from each other by solid masonry. I looked at some schematics and cross sections, and I understand now, as well as the points you're all making. I would lack that "separation" between the two steel liners here. I though that if you could run a boiler/furnace in the basement and a wood stove on the first floor up through a single chimney, then why couldn't you here. I get the distinction and differences now.

It looks like both NFPA 211 and the IRC Residential Construction codes also prohibit the practice, from the reading I've done since posting. And, it looks like it's a common thing insurance companies will inquire about from a coverage aspect.

So, I guess I'll drop the idea of two inserts back to back here and focus on what I can do to optimize my somewhat unique setup for the single insert.

I'd still love to hear ideas and feedback on just that...I welcome creativity as I may not know much about fireplace construction, but I'm a fully tooled up welder/metal fabricator/mechanic. I'd love to get some heat off the backside of the insert while still using that second back side for wood storage....

Here's where my head goes. MS Paint sketch below. I could make a C-shaped air channel that takes in air from down low, cycles it to the back of the insert, and then disperses it up top. And, it could both act as a physical barrier behind the insert, and a platform for wood. I can fit at least four big canvas carry bags of wood in the fireplace opening here, since the opening is pretty large. This would be functional from a storage AND heat output standpoint. Thoughts???

 

[begreen]

That idea would violate the required clearances for the insert unless there is at least 8" of masonry behind it.

 

[jaylude]

Where do you see that requirement? I looked through the installation clearances and manual for the unit, and hadn't seen anything related to rear / backside clearances or similar... I might have missed it?

 

[EbS-P]

Will the big 8” buck fit? Buck 91?? It’s essentially a stove.

 

[begreen]

Where do you see that requirement? I looked through the installation clearances and manual for the unit, and hadn't seen anything related to rear / backside clearances or similar... I might have missed it?

Sorry that should have been 10" if no firebrick. @bholler may have more insight. I am going by the insert's tested requirement.
If the insert needs to be installed in a masonry fireplace then this implies the type of required construction to surround the insert. It's all that it has been tested for.

CHAPTER 10 CHIMNEYS AND FIREPLACES - 2018 INTERNATIONAL RESIDENTIAL CODE (IRC)

ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.

codes.iccsafe.org

 

[bholler]

Sorry that should have been 10" if no firebrick. @bholler may have more insight. I am going by the insert's tested requirement.
If the insert needs to be installed in a masonry fireplace then this implies the type of required construction to surround the insert. It's all that it has been tested for.

CHAPTER 10 CHIMNEYS AND FIREPLACES - 2018 INTERNATIONAL RESIDENTIAL CODE (IRC)

ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.

codes.iccsafe.org

You are technically right but most inserts also just say a code compliant woodburning fireplace. A 2 sided fireplace can be code compliant. So kind of a gray area. I have installed inserts in open fireplaces and just covered the back side. One i bricked closed

 

[stovelark]

Beautiful fireplace. A nice free standing stove or insert would seem to be the cure all. I like the idea of a screen on the backside of the unit installed, to help cover the look and to let some radiance of heat come through to that side. Good luck, keep warm. I would remove that gas line from the fireplace too, if a wood burner is going in.