do we have any chimney experts out there?

[t walgamuth]

the other day at lunch we were discussing chimney fires and i stated that a good chimney fire could melt the clay liners.

one of the other fellows who ususlly knows his stuff said the fire couldn't get hot enough to melt them but you could have trouble if there were voids in the mortar joints.

anybody know the melting temp of clay tile and the burning temp of a good flue fire?

i had one once and the power of it was absolutely awesome.

scared me and i am fearless....

not

tom w

[A264172]

I'm no expert but I have read a little.

I would think clay, morter and brick would laugh off a chimney fires temps from a melting point prespective. The cracking from expansion and contraction due to the heat is what causes the problems. Structural problems for the chimney and wood framing ignites if it ends up getting exposed to the fire. Also flamable stuff shot out of the chimney can ignite roofs and anything else it lands on that can burn. Modern metal chimneys are rated at 2100 F so I would think a chimney fire's temps should be below that. Also your homeowners policy should cover a chimney inspection and repair after a fire. Don't burn after a chimney fire without an inspection!
Edit: The gasses associated with wood burning ignite at 1100 F so it would probably get a little north of that.

[Jim H]

...During a chimney fire, the flue gas temperature may well approach and at times even exceed 2000 degrees Fahrenheit...

SOURCE: http://www.csia.org/homeowners/Flue.html

Hope this helps some... 'way out of my usual field, though.

[t walgamuth]

thanks. i wonder at what temp the ceramic would melt?

tom w

[t walgamuth]

i found references to glaxze melting at anywhere from about 700 to 3100 degrees faranheit.

tom w

[A264172]

Originally Posted by t walgamuth

thanks. i wonder at what temp the ceramic would melt?

tom w

Depending on the material composition of the material 2800 F - 3200 F for firebrick/clay. But other ceramics vary.
http://pubs.acs.org/cgi-bin/abstract.cgi/iechad/1912/4/i10/f-pdf/f_ie50046a031.pdf?sessid=6006l3

[t walgamuth]

thanks.

we still don't have definitive answer on vitrified clay flue liners, right?

tom w

[Wes Bender]

Santa Claus responded, but his comments were deleted.................by the mods. Don't want to offend the little kiddies.

[A264172]

Originally Posted by t walgamuth

thanks.

we still don't have definitive answer on vitrified clay flue liners, right?

tom w

Tom, I've been thinking about that and researching it a lillte.

And I think there is no predictable melting point from one tile manufacturer to the next or perhaps even from batch to batch. One manufacturer claims to test at 1000 C (1832 F) for 30 minutes and I would think that UL 1777 ( http://ulstandardsinfonet.ul.com/scopes/1777.html ) would apply to anyone selling them in a modern market. But the ultimate melting point would depend on the exact chemical composition of the clay used to manufacture the tiles. There is a wide range of melting point for igneous rock that is determined by chemical composition. So if you want to know what temp a particular chimney will melt at you have to melt part of that chimney to find out.

[Carleton Hughes]

Charlie Bishop,oldtime Estate manager,dead now,once shared the following tidbit...."Waaal,you boin wood into yer chimbly ya gotta boin out the creosole what sticks to the linah.See,the linah's stuck wit'refractorin'cement can take alotta heat.
We'd wait 'til was a drivin' rain out,then we'd stuff straw up the chimbly,much as she'd take then light it afire.

You don yer Macintosh,step out an' see flames shootin'out the chimbly top you know that creosole's taken to burnin' good,that's what we done,you come back in you see black soot wit'the straw ash into the fireplace you know you done it good"

[t walgamuth]

i wouldn't try that!

one of the things i read suggested that the heat shock would shatter the flue liner. and the vibration from the burning would literally shake a lightly built chimney apart!

tom w

[soypwrd]

Originally Posted by t walgamuth

i wouldn't try that!

one of the things i read suggested that the heat shock would shatter the flue liner. and the vibration from the burning would literally shake a lightly built chimney apart!

tom w

That's it Tom, the heat will crack the tiles long before it's ever get hot enough to melt them. I experienced a chimney fire once and the whole house was shaking.

[dlssmith]

I saw a chimney fire at a neighbor's place one time. It was roaring, loud like an engine - and shooting flames about 5 to 10 feet out of the top. Fortunately the chimney was on the outside of the house, there was snow on the roof, and eventually the chimney just fell down. This was several miles from the rural FD, so they got there in time to put the smoldering remains out on the lawn. I don't know if the mortar just gave way from vibration, or if it was old and gone already - probably both.

It was probably around zero F at the time.

I had my 1918 chimney restored to the tune of $5000 a few years ago. They inserted a stainless steel liner and then filled around it with an insulating cement/fibre glass material. They rebuilt the top and put new caps on, and really secured it. I've had it cleaned once - I don't burn wood that often, and the Sweep said it still looks good.

[soypwrd]

No tiles in our chimney, we had a poured flue installed for safety and longevity reasons.

[t walgamuth]

when i had my fire, although i had never heard what to do....i did this:
i poured water on the fire and put it out. then i closed the dampers and called the fire department. by the time they got there...they were three blocks away....it was out.

it was pretty scarey. some folks said you can just let them burn but i would never do that! you may well burn the house down.

thanks for the comments everyone. i guess i lose the bet. not likely to melt the tile.

tom w