chimney blockage

[Zzyk]

First I'd like to say hi to everyone as its been awhile.
And now... a problem
Cleaned the chimney today as it seemed our summit has been burning poorly (low heat, minimal secondarily burn). Inside pipe just had some white ashy buildup. Chimney itself had a just a little soot except at the very top where there was a blockage of some sort. Not sure what was blocking it as I can't see up there but I managed to punch it out with the brush. Now the stove burns great again. Any ideas what this could be and if I should be concerned?
Thanks

 

[tigger]

The top of the pipe is where the creasote builds up the most. It forms where it is the coolest. Do you have a top plate? What about a block off plate? Insulates liner?

 

[Zzyk]

It's an insulated 6 inch liner in an 8x8 block chimney. Blockage was either on top or the last few inches. Otherwise chimney was reasonably clean. Puzzled.

 

[Hogwildz]

The top is where it will get blocked first. When you sweep, you must include the cap, any cap screen and top area of pipe.
Burn dryer wood, as this should not be happening with good dry wood.

 

[KindredSpiritzz]

bird nest maybe?

 

[bholler]

It is very common to get a ring of buildup at the top where the bare liner is exposed.

 

[Zzyk]

Used to get a bird's nest every spring until I knocked the rain cap off. All it would take is 2 days of not burning and they would have it plugged tight. Was not fun trying to remove it.

 

[Phoenix Hatchling]

Bird, squirrel, bats...?

 

[jatoxico]

Didn't any thing come down the flue into the stove that you could ID when you "punched it out"?

 

[Zzyk]

Nothing dropped down the flue and I didn't find anything on the ground or see anything on the roof. It would be good to get up there and see but the chimney is approximately 36 feet tall.

 

[Swedishchef]

Where'd the plug go that was blocking it? You knocked it out right?

Andrew