Chimney cap causing stain on exterior of chimney (PIC)

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bluefrier

Feeling the Heat
Jul 3, 2008
325
Maryland
Hi everyone,
I bought a new stove for this season a Buck 80 catalytic stove (official review coming soon). The issue I'm having is that the cooler flue gas temperature is icing on the cap and dripping down the side of the chimney, causing an unsightly stain. I'm tempted to take the chimney cap off but would like to know what are the pros and cons of doing so? any other solution or suggestion? Thank you in advance for your help.
 

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Hmm, from the reports of other cat stove users, there should not be much coming out of the top, as those cats burn so cleanly and the flue is so cool that you can touch it.
Is your wood good and dry, truly dry?
 
I do not have a cap on my chimney- everything is running fine, but I do not have one of those new fangled cat stoves....
 
Thank you for the comments guys. Yes the wood is good and dry, little or no smoke
from the chimney once the cat is engaged.
 
Is there an insulated liner directly connected to the stove or are you dumping into the terracotta liner to which the cap is attached? If it's the former, there's not much you can do to keep the flu gas any warmer. If it's the latter, an insulated liner would help.

I have an interior masonry chimney with perlite between the ss liner and the terracotta. Also wrapped the exposed block in the attic with R-25 fiberglass. On really cold days, I'll still get a few creo-cicles hanging from the cap. Haven't noticed any staining down the side, but my chimney is more square and brick is not as light colored.
 
bluefrier said:
Thank you for the comments guys. Yes the wood is good and dry, little or no smoke
from the chimney once the cat is engaged.

Well, that is one consideration for the wood but not the total picture. Also realize if your wood is not really dry it will mean the cat will not last nearly as long. Moisture and cats do not get along very well together.
 
pgmr said:
Is there an insulated liner directly connected to the stove or are you dumping into the terracotta liner to which the cap is attached? If it's the former, there's not much you can do to keep the flu gas any warmer. If it's the latter, an insulated liner would help.

I have an interior masonry chimney with perlite between the ss liner and the terracotta. Also wrapped the exposed block in the attic with R-25 fiberglass. On really cold days, I'll still get a few creo-cicles hanging from the cap. Haven't noticed any staining down the side, but my chimney is more square and brick is not as light colored.

Thanks for the shotgun update. There is a liner in the chimney but no insulation, u think that would make a big difference?
 
Backwoods Savage said:
bluefrier said:
Thank you for the comments guys. Yes the wood is good and dry, little or no smoke
from the chimney once the cat is engaged.

Well, that is one consideration for the wood but not the total picture. Also realize if your wood is not really dry it will mean the cat will not last nearly as long. Moisture and cats do not get along very well together.

Dennis, the wood is moisture meter certified and approved. ;-) The pipe and cap is pretty clean and the cat lights off easily and stays high in the active zone for most of the burn. I'm just trying to figure out how to keep the ice from staining the brick.
 
Mine is like that, never had the problem until I bought a new cap this year, I do not understand why the new cap does this versus the old cap, new stove also but did not notice it until I put the new one on and it was with in a week or so of putting it on.
 
bluefrier said:
pgmr said:
Is there an insulated liner directly connected to the stove or are you dumping into the terracotta liner to which the cap is attached? If it's the former, there's not much you can do to keep the flu gas any warmer. If it's the latter, an insulated liner would help.

I have an interior masonry chimney with perlite between the ss liner and the terracotta. Also wrapped the exposed block in the attic with R-25 fiberglass. On really cold days, I'll still get a few creo-cicles hanging from the cap. Haven't noticed any staining down the side, but my chimney is more square and brick is not as light colored.

There is a liner in the chimney but no insulation, u think that would make a big difference?

If the chimney is external to the house structure, then it will definitely help. Even if it's lower portion is w/in the house itself, you've got quite a bit exposed, so I'd say it would probably help.

If you decide to go with loose fill poured in like perlite or vermiculite, make sure you seal really well around the gap between the liner and the block off plate. If you don't, you'll have a constant trickle of insulation falling through the gap. I used stove door rope insulation coated with furnace cement to fill the gap. Caulking the outside edges of the plate won't hurt.
 
I want to take the cap off but what about water getting in the stove?
 
As far as taking the cap off, some people do and others don't. Mine is on but also mine is not designed with mesh screening on it..

As an aside question: I see two flues up there. Hmm... I thought one flue had to be taller (higher) than the other. Would adding 2' to your stove flue help any with the staining issue?
 
Shari, both flues are the same height. I'll have to check into that but all the houses in the
neighborhood are built that way. Thanks for pointing that out.
 
bluefrier said:
Shari, both flues are the same height. I'll have to check into that but all the houses in the
neighborhood are built that way. Thanks for pointing that out.


All the houses in our neighborhood are built with flues the same height also (everyone has a fireplace) - BUT - they were built in the late 1950's and I think codes have changed since then. :)
 
bluefrier said:
Backwoods Savage said:
bluefrier said:
Thank you for the comments guys. Yes the wood is good and dry, little or no smoke
from the chimney once the cat is engaged.

Well, that is one consideration for the wood but not the total picture. Also realize if your wood is not really dry it will mean the cat will not last nearly as long. Moisture and cats do not get along very well together.

Dennis, the wood is moisture meter certified and approved. ;-) The pipe and cap is pretty clean and the cat lights off easily and stays high in the active zone for most of the burn. I'm just trying to figure out how to keep the ice from staining the brick.

I still think that your wood is not as dry as it could be, moisture meter or not. I know how dry my wood is without a moisture meter. I really don't have a need for it. An insulated liner will help keep the liner clean but it will not prevent anything from condensing on the cap. Something is definitely condensing on the cap and it is coming from the wood, right??
 
Shari said:
As far as taking the cap off, some people do and others don't. Mine is on but also mine is not designed with mesh screening on it..

As an aside question: I see two flues up there. Hmm... I thought one flue had to be taller (higher) than the other. Would adding 2' to your stove flue help any with the staining issue?
I am pretty sure this is not a code, it can be a good solution to a down draft problem though.
 
I removed the cap and cleaned the bricks with no extra effort or chemical cleaner. rained
all day today and i'm surprise to see not even a drop of water in the stove or on the cat bypass
I'm going to leave the cap off for the rest of the season and see how it goes.
 
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