- Nov 27, 2012
- 0
Question:
Gentlemen:
I am building a stone shop on my farm. The gable end wall contains a chimney (24 x 24 inches). I am at the point in the chimney construction where I am installing the thimble. The stainless steel thimble I bought from the building supply outfit here was hardly thicker than a double thickness of aluminum foil. I opted instead to get a six-inch (nominal) diameter piece of 3/32" thick wall stainless pipe.
I have carefully cut a round hole in a section of eight-inch clay flue liner that will receive the thimble. As required by the building inspector, the thimble extends into the flue lining to the inside face of the lining. I am about to mortar in the thimble to the rock surrounding, and seal the stainless thimble to the flue lining with special high-heat firebrick cement. I have allowed all the appropriate clearances between the flue lining and the outer wall and chimney stones.
My question is this: because I have placed a thicker piece of stainless steel as a thimble into the flue lining, is there a danger of the thimble expanding from the heat of the stove and cracking the flue lining? Or will everything -- flue lining and stainless thimble -- expand at roughly the same rate with the heat?
Answer:
What you have isn't uncommon-----I've seen this before in a number of installations.
Here's the key: Your chimney connector that installs into the new thimble should extend as far into the thimble as possible for a good secure connection (don't extend into the flue, though). This will also keep the heat down, and keep the thimble clean of debris.
You will need an undersized connector to fit inside your new thimble. Vermont Castings makes a "thimble sleeve" in 6". Find a dealer near you to order. Or, have one made locally. It should be small enough in diameter to fit inside the thimble, as well into the pipe "below" in the installation. It should work just fine then.
Get some sleep now.
Gentlemen:
I am building a stone shop on my farm. The gable end wall contains a chimney (24 x 24 inches). I am at the point in the chimney construction where I am installing the thimble. The stainless steel thimble I bought from the building supply outfit here was hardly thicker than a double thickness of aluminum foil. I opted instead to get a six-inch (nominal) diameter piece of 3/32" thick wall stainless pipe.
I have carefully cut a round hole in a section of eight-inch clay flue liner that will receive the thimble. As required by the building inspector, the thimble extends into the flue lining to the inside face of the lining. I am about to mortar in the thimble to the rock surrounding, and seal the stainless thimble to the flue lining with special high-heat firebrick cement. I have allowed all the appropriate clearances between the flue lining and the outer wall and chimney stones.
My question is this: because I have placed a thicker piece of stainless steel as a thimble into the flue lining, is there a danger of the thimble expanding from the heat of the stove and cracking the flue lining? Or will everything -- flue lining and stainless thimble -- expand at roughly the same rate with the heat?
Answer:
What you have isn't uncommon-----I've seen this before in a number of installations.
Here's the key: Your chimney connector that installs into the new thimble should extend as far into the thimble as possible for a good secure connection (don't extend into the flue, though). This will also keep the heat down, and keep the thimble clean of debris.
You will need an undersized connector to fit inside your new thimble. Vermont Castings makes a "thimble sleeve" in 6". Find a dealer near you to order. Or, have one made locally. It should be small enough in diameter to fit inside the thimble, as well into the pipe "below" in the installation. It should work just fine then.
Get some sleep now.
