Please identify what is happening (pictures)

[RickBlaine]

Hello wood-burners!

I am prepping for this fall and am concerned about some mortar (?) bits falling on top of my stove....I have a 12 foot insulated liner through a clay-tiled brick chimney. The outside of the chimney was tuckpointed about 5 years ago and visually seems in fine shape. This summer, I noticed tiny bits of mortar that dropped onto the top of my awesome Englander 13. These bits fell between the slight gap where the insulated liner runs through the Roxul insulation resting on top of the block-off plate.

Can you please tell me if this is normal, or not? (this is 4 months worth of stuff on top of stove)

Here are some pics:


And here are pics before the install 6 months ago:
Looking down, looking up, and the part of the clay liner sticking above my chimney cap :

Thank you! Any help, threats, or advice would be welcome....

 

[Jags]

Hmmm...it does look like degradation of mortar. Would it be possible for the liner to be rubbing on some of it? Expansion and contraction (heat, cold)??? Being that you have an insulated liner I doubt that there is any danger but if it is bothering you I wouldn't be above calling in a pro to put a set of hairy eyeballs on the thing.

 

[Nick Mystic]

I'm assuming you have a rain cap on the top of the clay tile flue and that a top plate is sealed in place with silicone caulk. If that's not the case you could be letting moisture/rain water into the clay flue, which could contribute to the problem you have. Second, did you leave the opening around your block off plate where the liner drops through (where the roxul is exposed) because you thought it would be too much work to close it in with metal like the rest of the block off plate? Simply closing up that opening would likely eliminate any more debris dropping down onto your stove. It wouldn't answer your question regarding what is falling or why it is falling, but at least it would stop it from making a mess on the stove top.

 

[hwdemers]

Would it be possible for the liner to be rubbing on some of it? Expansion and contraction (heat, cold)???

the mortar bed between the tiles looks really loose, and in your picture you can see some gaps where it is no longer. I like his theory.

 

[RickBlaine]

Thank you for the replies, Gents.

Jags, that is a good point- that the insulated liner (also wrapped in that steel mesh "wrapper") may be rubbing against part of the original clay-lined flue tiles.

Nick, I do have a rain cap, but no silicone as it is more of a rain "cover". The cover is attached to the clay flue tile that sticks above the chimney cap via screws. As for the little opening between the liner and the block-off plate right above the stove, I used a custom piece attached with two large magnets (yes, magnets!) so that I can easily assemble or disassemble the whole set up.

hwdemers, thank you for your input. Are you referring to the theory of the liner rubbing (heat/cold cycles) against the old mortar, or the "water getting in" theory?

Am wondering if this is just the original excess mortar that was sticking out between the flue tiles?

Here is a picture of the top set up (the little black thing is my camera case) :

 

[hwdemers]

rubbing theory,

 

[Nick Mystic]

I have a Woodstock Classic in the lower level of our home that vents into a clay tile flue with no liner. I don't burn the stove all that much since our big Jotul F 600 is located in our living room upstairs where we spend most of our time. When I inspect the clay flue it is always nice and clean, but from time to time I have to scoop out some crumbled up creosote that has flaked off the inside of the liner and fallen down to the bottom of the clean out in the system. I've always thought that the expansion and contraction of the tiles probably caused this flaking off, or self-cleaning feature. When you installed your insulated liner you undoubtedly banged the sides of your clay tile flue, which might well have loosened up some of the already loose mortar. This same expansion/contraction cycle I alluded to could well cause that loose mortar to drop off over time. I doubt you have anything to worry about based on the photos you posted.

 

[RickBlaine]

You people are knowledge-answering machines! Thank you! It was my first install and between my buddy and me putting the liner through when the outside temp was about zero degrees (Chicago back in Feb/March 2014), and all the laughing and swear words we used at each other (I was freezing on the roof, he was in the fireplace waiting for me to thread the liner down to him) we most certainly banged the sides of the old clay flue tiles.