Advice on faulty wood-fired fireplace??


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Old 05-07-08, 11:41 AM
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Exclamation Advice on faulty wood-fired fireplace??

We had a wood-fired fireplace with two openings built onto an existing chimney in May 2007. We are now not convinced that this chimney was originally used for this purpose. The smoke starts off going up the chimney, but after about 10 minutes it starts balling out of both openings into the house with and without inside and outside drafts / wind. 9 Builders and fireplace advisors have had a look at it in the past year and we have had 9 VERY different opinions and guesses and "mmmmm's"

I have some photographs, a diagram (not to scale) with measurements and some details on what we have tried in past. Is there anyone out there able to give some expert advice (for a change)?? We are grabbing at straws on this end and here (in South Africa) we have not managed to find any solutions in the past year!

Thank you for your time and consideration.

Lana

Blaauwbergstrand, South Africa
 
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Old 05-07-08, 02:22 PM
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Thumbs up Hello Lana, welcome to our forums.

I am unsure what your fireplace looks like.
If you have pictures you can upload them to a free site like Photo Bucket and post links.

Is this fireplace manufactured by a company and installed in your home or a custom built one?
 
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Old 05-07-08, 02:30 PM
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So you have a fireplace that is open on both sides (two openings)? Not a chimney engineer here, but there is supposed to be a ratio of opening size to chimney size. You state that you installed fireplace to existing chimney? If you doubled the size of the opening with open on both sides, you have doubled the drafting needs of the chimney.

http://hearth.com/econtent/index.php...tes/info/1975/
 
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Old 05-10-08, 04:45 AM
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Originally Posted by GregH View Post
I am unsure what your fireplace looks like.
If you have pictures you can upload them to a free site like Photo Bucket and post links.

Is this fireplace manufactured by a company and installed in your home or a custom built one?
Dear Greg,

Thank you for your assistance. I have uploaded photos and a diagram to http://i286.photobucket.com/albums/ll82/LanaGroenewald. Below I included some specific data about our custom-built fireplace problem:

* When starting a fire, the chimney does draw the smoke out. Seemingly, as soon as the smoke builds up, the smoke pushes outward through both openings (Fireplace.jpg) into the interior of the house. Halfway up inside the chimney is a piece of pipe (about 30 cm long and 4 cm wide) sticking out of the bricks downwards and seemingly running into the ceiling. I discovered that two days ago and it has left me wondering that there is perhaps air / smoke flowing into / from the ceiling area and maybe that is adding to the air-flow problem (in the sense that the chimney is not “sucking” as it should)? Not to mention a fire hazard...

* You will note in the attached Chimney_Inside.jpg and Fireplace_inside.jpg that the interior towards the chimney opening was not worked down smoothly. We have been told that this too could be problematic (?). The person was however not convinced that fixing this would solve the problem.

* The chimney outside: Several people have informed us that the height of the chimney in relation to the nock of the roof is fine. The attached photo (Chimney_Outside.jpg) was taken from the angle from which the wind blows, thus the nock (to the right of the chimney) is not obtrusive. We have made fires when the wind blows and when it is completely quiet and there is no difference whatsoever in the problem.

* You will note in Fireplace.jpg that we had both openings made smaller with custom-made metal plates. Someone suggested this would work, but it did not make any difference. The metal plates on both openings have (flat, almost tight-fitting) "lids / covers" to close either the kitchen opening or the dining-room opening (See Opening_with_Cover.jpg). Even with all windows, doors and one opening of the fireplace closed (to eliminate possible drafts) - the smoke still pushes into the interior through the remaining opening. Thus, having one side closed did not solve the problem. The measurements of both openings (with and without the fitted metal, is shown in Fireplace_Diagram.jpg.

* We have also done a test with newspaper. We covered the one opening and then slowly reduced the size of the other opening. Once it was two-thirds covered, the smoking problem stopped. This was a bit of a relief; however we were left with a very small and unpractical gap through which to operate. We hope to make BBQ's in there. That is why we thought of perhaps removing a / the section of the fireplace on kitchen side. We would wish to keep both openings with the metal "lids / covers", but the fireplace would obviously now be much smaller (probably half the size). The fireplace would then extrude towards the dining room only and the kitchen would only have an opening (with “lid / cover”) in the wall. Perhaps this way of reasoning the theoretically incorrect? I hope you could advise.

We have (another) eager builder wishing to break down this kitchen section, but I have put him on hold. I wish (a.k.a. desperately need) to know what dimensions / ratios / workmanship / plan we SHOULD BE WORKING WITH before we go ahead with "just another idea..."

* The original builder saw fit to build it from normal bricks (double-layered) and mortar only. The floor of the fireplace was built with rows of lintels and covered with mortar. Nothing is lined or insulated and this worries me - perhaps I'm now just overtly paranoid? After only 4 fires, the fireplace section on the kitchen side has split from the interior wall. A fine crack almost all around is visible. Smoke has not yet escaped from here. This is also why we are semi-keen to remove the kitchen section – before the house burns down.

* An electric-operated fan is not an option for us. The idea behind the fireplace is to save electricity and expenses. A friend suggested that we consider one of those "mushroom-looking" balls that is fitted on top of the chimney that spins due to the wind and rising heat in the chimney (?).

Thank you again for your time and thoughts.
 

Last edited by LanaGroenewald; 05-10-08 at 04:46 AM. Reason: update
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Old 05-10-08, 04:55 AM
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Originally Posted by twelvepole View Post
So you have a fireplace that is open on both sides (two openings)? Not a chimney engineer here, but there is supposed to be a ratio of opening size to chimney size. You state that you installed fireplace to existing chimney? If you doubled the size of the opening with open on both sides, you have doubled the drafting needs of the chimney.

http://hearth.com/econtent/index.php...tes/info/1975/
Thank you for the reply. I have read the answer at the link you provided. I wish we knew that our builder was (obviously) not aware of such measurements or problems! Thank you again.
 
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Old 05-10-08, 06:56 AM
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based on your testing I would say chimney size is to small for the amount of heat put off by the fire. Also useing conventional brick and mortar, as you have seen they are too heat sensitive and you are already getting cracks. you really need to use fireplace mortar and firebricks. barring that use solid bricks and a lime mortar and that will get you a slightly longer life span.

remember murphy was an optimist
 
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Old 05-10-08, 07:58 AM
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The link that twelvepole provided explains the drafting needs quite well.
It is possible to increase draft by increasing chimney height but in your case I don't think it would be enough.

I would have suggested that if you wanted to maintain the see through look you could have heat resistant glass doors fitted to each opening and close one side when burning.
However, the fact that heat resistant bricks and mortar were not used I think your best option is to remove the fireplace and chimney and start over.

One last thought is that you need to realize that an open fireplace like what you have will not save any money on heating costs.
An open hearth will draw heat from your home and push it up the chimney.

You need to consider metal heat reclaiming inserts to be able to look at a nice fire and enjoy the benefit of the heat.
 
 

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