View Full Version : burn pattern

dan orourke
07-06-2007, 10:31 AM

Matt Fellman
07-06-2007, 12:43 PM
I've always just thought it was from burning wet or green wood. The pattern follows that of a typical fire. The center is where the fire is burning hot enough to keep the soot from forming but the edges aren't. I've seen similar markings many times and have never commented on it. I'm curious to see what the others say.

neal lewis
07-06-2007, 02:50 PM
Dan, I'm sure you saw the problem with wood trim clearance at the fireplace opening.

Victor DaGraca
07-06-2007, 06:21 PM
That thing had a "meltdown"
Some distortion on the andirons.

The black soot is created by "normal" burn.
When the fire is accelerated and reaches critical super nova status it will consume the black soot.

Been there ...done that... threw in the chimney flares when I heard the train a'comin.

However that doesn't look bad. Just looks like the ashes accumulated, keeping the soot from forming.

wayne soper
07-06-2007, 06:49 PM
The answer to your question is YES! They had the logs stacked to the damper. Soot does not form where the flames are but above. Was the home rented? That would be typical non homeowner activity.

Matt Fellman
07-06-2007, 07:07 PM
I'm a little confused... from looking at that picture is shows where the flames have been. How do we know the logs were stacked to the damper? If they were we'd need to see 2 feet up past the damper to see the markings that are in the back of the fire box wouldn't we? It looks like the soot outline is coming to a point near the damper which would mean a normal fire.

Bob Harper
07-06-2007, 08:13 PM
Interesting pics. Based upon the limited info. presented, we can make some assertions and ask some more questions.

We are presented with a large masonry fireplace. It appears to be about 42" wide by ~30" deep x ~34" tall. However, it has a small grate flanked by andirons, which are lower than the grates bars. The result is a fulcrum for logs to burn in half then flip to either side and continue burning at a much slower rate since it is not sitting up in the breeze. The main fire seems to be burned very hot but narrow as noted by the height of the truncated cone on the rear wall. The sides see primarily smoldering fires as evidenced by the soot patterns. It is interesting to note the virtual outline of the andiron post in the soot on the right side. With such a deep, squared off firebox, air rolls in the sides and apparently, the andiron is creating enough turbulence to wash one spot on the side. The rest of the char marks on the floor confirm smoldering chunks of wood are routinely allowed far from the coal bed, thus creating gobs of creosote and CO. I would like to know how much 3rd degree creosote is in the flue.

Aside from the aforementioned facing clearances, I would be concerned about the flue size and condition, termination, etc. from a Level II. This ought to have a very large flue, which works against low, smoldering fires btw.

They ought to get a proper grate that fits the Fp. Look at their firewood. If their logs are cut 24-30" then the grate should be able to accomodate them without them flipping to the sides. They should be instructed to keep those ashes shoveled out better as seen in the patterns.

Is that hearth extension terrazzo? Did you get a peek at what's under it? With such a deep hearth, I would be concerned they used plywood forms and left them in place, which is of concern. That is unless this is slab on grade.

Back to the burn height question: if they were burning logs stacked up way high, the width of the truncated cone on that rear wall would be much wider with the apex much higher. As it is, this pattern if similar to what you see with teepee fires. Wayne, if they stacked the logs to the damper, you wouldn't see hardly any scorching on the rear wall as most of the flame would be in the smoke chamber and flue...... at least until burning logs rolled out into the room.

Interesting ideas presented!