Using whole-chimney cap over liner?

[TradEddie]

Has anyone had any experience using a whole-chimney cap instead of a cap mounted on the liner? My chimney originally had a slate flagstone raised on bricks, which looked very nice, and matched the style of the old farmhouses nearby. Last year I had a new insert and liner installed, now I have just a round cap on the liner, which doesn't look nearly as good, and since this will drip rain down onto the crown, I expect over time it will create discolored soot streaks down the chimney exterior. I want to keep the ability to sweep top down, so rebuilding the original flagstone is out. There are rectangular whole chimney covers which mount onto the exterior masonry and seem like they would solve my dripping concerns and restore some of the original shape and proportions to the chimney.

My concern is clearance above the top of the liner. Since my terracotta flue extends several inches above the crown, and then the liner support plate takes up several more, I'm worried that the standard 10" to 12" caps could cause draft restrictions. Are there any codes or guidelines for this, especially if I consider building my own?
Also it's not clear from online descriptions if these caps are hinged or if they would need to be unbolted to sweep.

Any thoughts?

TE

 

[Ashful]

I have flag stone toppers on all of my chimneys. Makes getting the liner in real fun, as some of these slabs are enormous, but I've never seen a reason to get rid of the flagstone when installing a liner. One of my newer chimneys is setup just like yours, with the clay tile liner protruding an inch or two above the crown, which is then built up an inch or two beyond the stack. I think that topper sits on about four courses of brick, so there's still a good 8" - 10" between the top of the clay liner and the flagstone. I simply cut a swatch of 3/4" stainless mesh, rolled it into a drum, and hose-clamped it onto the clay tile flue.

Next month, I'll be installing a 6" insulated liner in that 8" clay tile liner, and keeping the same wire mesh screen and flag stone top. The installer has a seal ring that he installs to cover the gap between the 6" stainless and the 8" ID / 10" OD clay tile.

 

[BrotherBart]

I have two of these on my side by side lined terra cotta flues. Love the things.

http://www.chimneylinerdepot.com/store/1092/category/6-inch-Deluxe-Terra-Cotta.html

 

[TradEddie]

I have flag stone toppers on all of my chimneys. Makes getting the liner in real fun, as some of these slabs are enormous, but I've never seen a reason to get rid of the flagstone when installing a liner. One of my newer chimneys is setup just like yours, with the clay tile liner protruding an inch or two above the crown, which is then built up an inch or two beyond the stack. I think that topper sits on about four courses of brick, so there's still a good 8" - 10" between the top of the clay liner and the flagstone. I simply cut a swatch of 3/4" stainless mesh, rolled it into a drum, and hose-clamped it onto the clay tile flue.

Next month, I'll be installing a 6" insulated liner in that 8" clay tile liner, and keeping the same wire mesh screen and flag stone top. The installer has a seal ring that he installs to cover the gap between the 6" stainless and the 8" ID / 10" OD clay tile.

The original flagstone was cracked, and the bricks and mortar on the risers were in very bad shape, its a miracle that flag didn't come crashing down. Repairing/replacing the flag would have been expensive, and prevent sweeping the liner from the top, so I removed the flag and bricks and rebuilt the crown. My chimney also has an unused flue, and it's very close but offset from the working flue, so I probably couldn't cap both and capping only one would not look good. What I was thinking was something like this:

http://www.chimneylinerdepot.com/store/1247/product/1749-gelco-ss-chim-protr-cap-12inmsh-17x49.html

TE

 

[BrotherBart]

I have the same deal. Both are right next to each other with a slight height offset. I just have to open one before I can open the second one because the top overlaps a bit. Those that cover both often have a problem with negative pressure pulling the smoke and CO from the active one down the other one into the house.