Crystal like creosote in firebox? (accumulating with ashes)

[Biketrax]

I have a wood-stove insert in my basement. It is about 12 years old. Note: the vent pipe on the front ceiling of the firebox is shot and needs replacing.
I wasn't able to clean my chimney and exhaust stove pipe from my wood-stove last 2 years. (Due to injury)

The fire does not seem to be venting as easily and isn't burning as the prior years. For the first time I am accumulating these crystal like creosote clumps with the ashes.
IS this in fact CREOSOTE? PS I am burning high and hot.
Also burning elm for the first time ever could this be it?
I Will try and replace the vent pipe and also try and clean the stack pipe and chimney before the winter is over at first opportune moment.
However why is this happening? Could it be from anything other than what I mentioned?
thanks

 

[Motorsen]

Hi there! These crystal clumps are they black? If so it's most likely creosote. You say you burn "high and hot". If that's right i think the crystal deposits are grey like ash. If so then the crystals are ashes that sinters together to clumps or a layer in the firebox. They should break up into smaller clumps if you hit them hard with for instance the ash shovel or another hard object. This can happen when burning hardwood with some mineral content at high temperatures. I get it too, the grey sintered clumps that is, burning Ash.

Motorsen

 

[066blaster]

I get the same thing, I have a insert as well. It seems I get a thin layer of black Shiney creasote and then ash sticks to it. Then when the stove gets good and hot it flakes off. I scrape mine every couple of weeks. My firebox is really wide. I think that causes the smoke to hang in there longer when I don't have a really hot fire in it.
It's been a warmer winter that might be some of your problem. Mine burns clean when it's cold out and I keep a good fire 24/7. When it's in the 30's I keep a smaller fire and it goes out and smolders once in awhile, but It would chase us out of the house if I kept it going hot.

 

[mbergeon]

Elm makes clinkers, that is what you have.

 

[NSMaple1]

I think I would get the pipe & chimney cleaned ASAP.

Even if I had hire someone to do it.