Here's a photo of my existing chimney and you can see that it has a clay half-round cap covering the outlet. This matches the one on the old furnace chimney, the 'tunnel' runs north / south on both.
I'd like to preserve this after the liner install but I'm not sure the new SS cap will fit inside it or whether I even need the SS raincap with this. I will have to remove it to install the new top cover when the liner gets put in but since it's not mortared in place that's not a problem. IIRC this clay cap is 18" long and I don't really remember how far it sits over the real opening but I've never had any water infiltration problems with it in the old firebox. My intention years ago when I first installed it was to also install a woven wire screen .5x.5 to keep birds / bats from getting in but I've never had a problem with either one. I will probably bump this up when installing the top plate for the liner, I had hoped to increase height of the clay cap about 2" above the concrete.
These types of caps were prevalent in the early 20th c although most of the ones I've seen in books are taller than this one. This is 15" ID, 7.5" radius height.
Looking for comments
thx
Steve A
I'd like to preserve this after the liner install but I'm not sure the new SS cap will fit inside it or whether I even need the SS raincap with this. I will have to remove it to install the new top cover when the liner gets put in but since it's not mortared in place that's not a problem. IIRC this clay cap is 18" long and I don't really remember how far it sits over the real opening but I've never had any water infiltration problems with it in the old firebox. My intention years ago when I first installed it was to also install a woven wire screen .5x.5 to keep birds / bats from getting in but I've never had a problem with either one. I will probably bump this up when installing the top plate for the liner, I had hoped to increase height of the clay cap about 2" above the concrete.
These types of caps were prevalent in the early 20th c although most of the ones I've seen in books are taller than this one. This is 15" ID, 7.5" radius height.
Looking for comments
thx
Steve A