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fireplace open on two sides


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You're going to find that it doesn't comply when applying those dimension restrictions. At least, they usually don't. The proportions are all screwed up when compared to the stuff you're referencing.

Check hearth dimensions.

After that, look for a UL listing label, tell the folks to have a Level II inspection on the chimney.

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BTW, how are you getting photos of the interior before you get there?

I google addresses of pending inspections to see what I can find in advance. Sometimes it prepares me to zero in on things, such as it did in this case.

The front alone is 6 sq ft. Add the side in and it's probably over 8. The hearth only extends 16" so it's sized for 6' or less.

I'll be referring the matters to the chimney pro. I already explained it all to the client and they are expecting it.

Thanks to all for the input.

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. . . The front alone is 6 sq ft. Add the side in and it's probably over 8. The hearth only extends 16" so it's sized for 6' or less. . .

Why would you add the side opening to the front opening when considering the size of the hearth extension?

The point of the chimney-opening/hearth extension size ratio is to protect the floor from radiant heat. A larger opening has the capacity to throw more radiant heat at the floor so it needs a larger hearth extension.

The front opening and its hearth extension should be considered as one case and the side opening as another. They're not additive.

Does someone have a reference that says otherwise?

- Jim Katen, Oregon

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Somewhat thread drift.......

About 35 years ago, a mason building a fireplace in a house I was building described the opening dimensions relative to the depth of the fireplace as critical so the thing would draw.

He was insistent that the opening height be 2/3 of the width and the depth.

Anyone else ever heard that?

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About 35 years ago, a mason building a fireplace in a house I was building described the opening dimensions relative to the depth of the fireplace as critical so the thing would draw.

He was insistent that the opening height be 2/3 of the width and the depth.

Anyone else ever heard that?

Rumford never heard of it.

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It's a bricky thing. The old timer who taught him to lay brick used that formula, and he probably got it from the the old timer before him. When I worked masonry every firebox was exactly the same, because they worked. Why would you expect anything different from someone content to lay brick, one after another, over and over, gazillions of times.

Tom

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Somewhat thread drift.......

About 35 years ago, a mason building a fireplace in a house I was building described the opening dimensions relative to the depth of the fireplace as critical so the thing would draw.

He was insistent that the opening height be 2/3 of the width and the depth.

Anyone else ever heard that?

I haven't heard that one. But I have observed that, among the building trades, masons are the most susceptible to superstition & folklore and, without a doubt, the most resistant to change of any kind.

- Jim Katen, Oregon

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Maybe they simply know what they are doing. Long experience has it's virtues. We just can't always explain things that work, in terms of codes and existing science. . .

I think it's more likely that they believe that, because they've always done something a certain way and it's always worked, then it must be the only way that it will work. I find that mentality a lot, but especially with masons.

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Sorry I didn't respond sooner but I've been fighting a stomach flu bug. Nasty it was but i got it beat now.

In the case of this fireplace, the heart extension from the side portion was too short even if you apply the < 6' rule. It extended 16" out which is fine but the side portion where it intersects with the dining room wall extended only 6" from the firebox opening.

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  • 3 months later...

Maybe they simply know what they are doing. Long experience has it's virtues. We just can't always explain things that work, in terms of codes and existing science. . .

I think it's more likely that they believe that, because they've always done something a certain way and it's always worked, then it must be the only way that it will work. I find that mentality a lot, but especially with masons.

Boy, is there some truth to that. I remember the first time I constructed a true Rumford fireplace around 1976, according to all of his original dimension ratios (without asking the company owner). He had heart failure swearing it would never work and that I'd have to tear it down. The home owner loved it and said later that it would "run you out of the room" it works so well.

Then there was the time I raised the smoke shelf to meet the height of the open damper door to reduce turbulence, which was met with equal panic, but worked perfectly.

Masons are much like track home builders - a little variation here and a little design drift there and soon you don't have the original at all, but it remains the gospel as if no changes had occurred - kinda like that whispered phrase that is passed around a circle of people and arrives at the other end nothing like it began.

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BTW, if you locate a book about the modifications to fireplaces performed by Count Rumford, all of the dimensions are relative to the height and width of the fireplace opening. I'll try to locate my copy of the book and scan and post the formulas.

Codes, no doubt, have made masonry fireplaces safer, but they are the worst thing that ever happened to their aerodynamics and heating performance. Rumford was way ahead of his time and had the fireplace as tweaked as it's ever been.

The newer metal double-walled construction fireplaces introduced a new dimension to convection in a fireplace - an option not available in Rumford's time. But, he capitalized upon the ventura effect to keep the most heat possible within the firebox while just skimming off the smoke, and maximized that heat through radiation with his extreme reflecting walls - all quit brilliant.

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The largest majority of 100 plus year old fireplaces I see around Kentucky are coal burning fireplaces.

Way shallow with metal grate to hold the coal off the floor and a metal cover to radiate the heat into the room. Sometimes the cover is still there. Sometimes not.

In any case, they're mostly useless nowadays, though I've seen a few with funky gas logs installed in them.

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Many of the very old fireplaces in the downtown parts of Richmond are very shallow for another reason. tHey were designed to burn coal within a cast iron coal basket. The Copperclad cook stove I used in one of my 100+ year homes had in ter-changeable cast iron grates for the firebox - one for wood and one for coal.

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The largest majority of 100 plus year old fireplaces I see around Kentucky are coal burning fireplaces.

Way shallow with metal grate to hold the coal off the floor and a metal cover to radiate the heat into the room. Sometimes the cover is still there. Sometimes not.

In any case, they're mostly useless nowadays, though I've seen a few with funky gas logs installed in them.

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[:-thumbd]

I think the gas burninng coal basket replicas are a nice touch. If I had such a fireplace, I'd install them.

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  • 3 weeks later...

The newer metal double-walled construction fireplaces introduced a new dimension to convection in a fireplace - an option not available in Rumford's time. But, he capitalized upon the ventura effect to keep the most heat possible within the firebox while just skimming off the smoke, and maximized that heat through radiation with his extreme reflecting walls - all quit brilliant.

You do mean "Venturi" effect (not "ventura" as in "Ace")? [:)]
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