Fireplace about done.... Will it draft?

[Awshin]

So, I posted on here about two years ago with fireplace plans. My design is ultimately much simpler than I had planned.

Here is the near finished product.

6'x4'
Marble hearth
Gas assist
2 24" square flues
Two 6" air intakes running from outside the house.
Of course, I'm worried it won't draft. My house is completely insulated with closed cell foam.

 

[bholler]

So, I posted on here about two years ago with fireplace plans. My design is ultimately much simpler than I had planned.

Here is the near finished product.

6'x4'
Marble hearth
Gas assist
2 24" square flues
Two 6" air intakes running from outside the house.
Of course, I'm worried it won't draft. My house is completely insulated with closed cell foam.

View attachment 279819

What is the overall volume of open space of the faces? Also how is that ridge beam that ends at the chimney supported? It doesn't look like you have the required 2" clearance to combustibles there.

 

[Awshin]

What is the overall volume of open space of the faces? Also how is that ridge beam that ends at the chimney supported? It doesn't look like you have the required 2" clearance to combustibles there.

Opening is 24 square feet on each side. Volume? Maybe 4 feet deep.
There is a laminate beam goes all the way through, but the 2 - 24 inch pipes are insulated and about foot from the beam.

 

[bholler]

Opening is 24 square feet on each side. Volume? Maybe 4 feet deep.
There is a laminate beam goes all the way through, but the 2 - 24 inch pipes are insulated and about foot from the beam.

Ok they are insulated chimney pipes? That makes things different. When you said 24" square I assumed they were clay tile flues.


As far as drafting it will depend upon the height of the damper the design of the throat the design of the smoke chamber and whether both flues work together as intended or not. In addition I really don't see how 2 6" air supply ducts are going to supply enough combustion air. But purely by the numbers it should have enough volume to draft properly.

 

[Awshin]

They are the clay pipes. They insulated and shielded around the beam.

My fingers are crossed. I will post more once I start burning.

 

[bholler]

They are the clay pipes. They insulated and shielded around the beam.

My fingers are crossed. I will post more once I start burning.

How are they insulated and shielded???

 

[Awshin]

I don't remember exactly. I just remember them saying they insulated and shielded around the beam.

 

[bholler]

I don't remember exactly. I just remember them saying they insulated and shielded around the beam.

There is nothing in code allowing that at all it never should have passed inspection. If I was inspecting it for a realestate sale I would have to deem it unsafe to use

 

[BCC_Burner]

Is that ridge beam actually structural, or just for aesthetics? It looks more like the latter than the former to me, in which case it's likely discontinuous and doesn't run in between the two flues at all. That roof framing might just be scissor trusses.

We see faux ridge beams in rooms like that all the time out here.

 

[Bad LP]

Am I reading this correctly?

You have a beam in the flue chase that contains 2 clay flues?

That’s unpossible.

 

[Awshin]

Am I reading this correctly?

You have a beam in the flue chase that contains 2 clay flues?

That’s unpossible.

I think so.

 

[Awshin]

Is that ridge beam actually structural, or just for aesthetics? It looks more like the latter than the former to me, in which case it's likely discontinuous and doesn't run in between the two flues at all. That roof framing might just be scissor trusses.

We see faux ridge beams in rooms like that all the time out here.

I know it was a laminate beam all the way across. It was supported until the fireplace was built and then the support was removed.

 

[Awshin]

There is nothing in code allowing that at all it never should have passed inspection. If I was inspecting it for a realestate sale I would have to deem it unsafe to use

Fire risk?

 

[BCC_Burner]

I know it was a laminate beam all the way across. It was supported until the fireplace was built and then the support was removed.

Well, disregard my idea then. That's something.

 

[Awshin]

Okay, spoke with the engineer. They removed all the wood after it was braced by the block.

 

[bholler]

Okay, spoke with the engineer. They removed all the wood after it was braced by the block.

That still isn't ok. The chimney needs 2" clearance to combustibles which means that beam cannot be supported by the chimney.

 

[bholler]

Fire risk?

Yes absolutely

 

[Awshin]

Hmm. Even if there is a sizable gap between the block at the chimney flu e?

 

[Awshin]

Yes absolutely

Going through my pics to see what it looks like.

 

[bholler]

Hmm. Even if there is a sizable gap between the block at the chimney flu e?

Absolutely. There is no way your chimney meets code if it is supporting that beam and is clay lined.

 

[Awshin]

Well damn.

 

[Corey]

Wow, now that is a fireplace!!

Bit late now, but there are books on fireplace design. My interpretation is that there are design 'rules' and 'equations' for making a well built/functioning fireplace. Flue height, area, throat, smoke shelf, openings, etc should all have relative dimensions, placement, geometry, etc. So really just a matter of picking the size and following the design criteria - so shouldn't be a lot of questions if it will or won't work.

handbook of fireplace design at DuckDuckGo

DuckDuckGo. Privacy, Simplified.

duckduckgo.com

(broken link removed to https://www.gobrick.com/docs/default-source/read-research-documents/technicalnotes/19-residential-fireplace-design.pdf)

https://www.rumford.com/pdf/NYSCMATekSpec35.pdf

etc...

Conversely, this fireplace seems to be 'off the charts' on size and scale, so who knows! I'd be a little worried you might not be able to make enough heat to keep two "24 inch square" flues drafting strong enough. (I'm taking that to be two 24" x 24" flues = or ~1150 square inches of opening ...where some of the larger flues seem to top out at a couple hundred square inches ) ...or that you might heat one and have a downdraft in the other. But I guess the only way to tell now is to stick half a cord of wood in that thing, light it up and see!

Good luck - would certainly be a sight to see that burning on a cool night!

 

[Awshin]

Haha, I built a mile worth of road through hardwoods to get the driveway. All that wood might last me a winter.

 

[bholler]

Haha, I built a mile worth of road through hardwoods to get the driveway. All that wood might last me a winter.

Did your engineer bother to check codes for chimney construction before designing this? Are you sure they cut the beam off? How much solid masonry is between that beam and the clay liners? Honestly I wouldn't light it untill all of those questions are answered.

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

This is what should have been followed in the design and construction of your fireplace.

 

[Awshin]

Did your engineer bother to check codes for chimney construction before designing this? Are you sure they cut the beam off? How much solid masonry is between that beam and the clay liners? Honestly I wouldn't light it untill all of those questions are answered.

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

This is what should have been followed in the design and construction of your fireplace.

I have no idea. An engineer checked the plans.