Kind of hard to explain this but here goes.
First of all I have a Masonry Clay lined Chimney in good shape, it was well built by a preacher man that used to live here in the late 60's who was also a mason. It goes right up thru the middle of my ranch style house. He started in the basement and poured 3 ft by 3 ft 6 inch deep concrete pad on the basement floor which the basement floor is most likly another 6 to 8 inches of concrete. I think this is one reason the flue is still in good shape as its not going to be shifting unless there is an earthquake.
So anyhow, when I first got the stove and before I really knew how to operate it I hooked the stove's 6 inch outlet to the masonry chimney using 2 pieces of 6" pipe and one 6" elbow. My chimney is a 7"x11" and has an 8" thimble, and I used an adapter at the thimble. The chimney is 25 foot tall.
My chimney has a clean-out door and even when the flue is cold I can open that door and feel the air being sucked up the chimney when I put my hand in the door.
But back then, I at the time I didnt know if I was operating the stove correctly and I was having trouble getting the stove to heat up and the wood to burn with the door shut. I could get the wood a blazing and everything looked good but no heat was building in the stove and when I shut the door things would eventually go out. Sounds like 100 other stories on this board.
So what I did was I swapped out the 6" pipe and put in 8" pipe all the way to the 8" thimble on my 7"x11" masonry flue. My 6" to 8" adapter was now sitting in the top of the stove's 6" outlet then 8" pipe the rest of the way.
This improved things alot better plus I was at the time learning better how to operate the stove. My thought in going 8" instead of 6" up to the thimble was that I needed to provide a bigger volume of air that was heated to feed the masonry 7x11 flue. The 6" pipe and its smaller volume of air was cooled by the time it flowed up to enter and feed the bigger sized flue. The 6" pipe was single walled and ran for about 6 feet with one 90 degree turn. So heat was being given off that length of pipe. My thought was its volume of heated air being cooler wasnt enough to feed my masonry flue.
So to continue , my 8" pipe gong all the way down to the stove top with its bigger volume of air especially being closer to the hottest part of the system the stove , well I am pushing a bigger sorce of heated air to the entry point into the masonry flue thimble and feeding the 7x11 flue much better.
The results were improved but not as good as I would think running a 6" inch liner insulated all the way.
One other thing is I stuffed the flue just below the thimble with high temp insulation to eliminate the leaking flue clean out door.
So after having some issues with the stove getting too hot I decided to go back to the 6" pipe to see how things would work, well I could hardly get the stove going again it was same ole story trying to get the heat up and close the door.
For some added info here, With the 8" pipe install I have to use the manual flue damper , with the air intake completely closed and the manual flue damper completely closed on the 8" pipe I can still have the stove rockin at 400 flue temps about 12 inches up and stove top temps at 800 - 850. So the draw is good.
I will say even with the 8" the stove is sometimes hard to start as some of you remember my wanting to just throw some big splits on and get it going quickly before leaving for work. What I have to do is put some smaller stuff up front right on the coals to get burning hot and fast to heat up the stove.
Has anyone seen or heard of a situation like this with the 6" vs 8" running to a masonry flue?
First of all I have a Masonry Clay lined Chimney in good shape, it was well built by a preacher man that used to live here in the late 60's who was also a mason. It goes right up thru the middle of my ranch style house. He started in the basement and poured 3 ft by 3 ft 6 inch deep concrete pad on the basement floor which the basement floor is most likly another 6 to 8 inches of concrete. I think this is one reason the flue is still in good shape as its not going to be shifting unless there is an earthquake.
So anyhow, when I first got the stove and before I really knew how to operate it I hooked the stove's 6 inch outlet to the masonry chimney using 2 pieces of 6" pipe and one 6" elbow. My chimney is a 7"x11" and has an 8" thimble, and I used an adapter at the thimble. The chimney is 25 foot tall.
My chimney has a clean-out door and even when the flue is cold I can open that door and feel the air being sucked up the chimney when I put my hand in the door.
But back then, I at the time I didnt know if I was operating the stove correctly and I was having trouble getting the stove to heat up and the wood to burn with the door shut. I could get the wood a blazing and everything looked good but no heat was building in the stove and when I shut the door things would eventually go out. Sounds like 100 other stories on this board.
So what I did was I swapped out the 6" pipe and put in 8" pipe all the way to the 8" thimble on my 7"x11" masonry flue. My 6" to 8" adapter was now sitting in the top of the stove's 6" outlet then 8" pipe the rest of the way.
This improved things alot better plus I was at the time learning better how to operate the stove. My thought in going 8" instead of 6" up to the thimble was that I needed to provide a bigger volume of air that was heated to feed the masonry 7x11 flue. The 6" pipe and its smaller volume of air was cooled by the time it flowed up to enter and feed the bigger sized flue. The 6" pipe was single walled and ran for about 6 feet with one 90 degree turn. So heat was being given off that length of pipe. My thought was its volume of heated air being cooler wasnt enough to feed my masonry flue.
So to continue , my 8" pipe gong all the way down to the stove top with its bigger volume of air especially being closer to the hottest part of the system the stove , well I am pushing a bigger sorce of heated air to the entry point into the masonry flue thimble and feeding the 7x11 flue much better.
The results were improved but not as good as I would think running a 6" inch liner insulated all the way.
One other thing is I stuffed the flue just below the thimble with high temp insulation to eliminate the leaking flue clean out door.
So after having some issues with the stove getting too hot I decided to go back to the 6" pipe to see how things would work, well I could hardly get the stove going again it was same ole story trying to get the heat up and close the door.
For some added info here, With the 8" pipe install I have to use the manual flue damper , with the air intake completely closed and the manual flue damper completely closed on the 8" pipe I can still have the stove rockin at 400 flue temps about 12 inches up and stove top temps at 800 - 850. So the draw is good.
I will say even with the 8" the stove is sometimes hard to start as some of you remember my wanting to just throw some big splits on and get it going quickly before leaving for work. What I have to do is put some smaller stuff up front right on the coals to get burning hot and fast to heat up the stove.
Has anyone seen or heard of a situation like this with the 6" vs 8" running to a masonry flue?