long story short, I have a very old house and wanted a better source of heat than oil so I installed a stainless flex liner down my clay flue and hooked up a baby bear I bought online. Has great draft and pumps out the heat but there is something happening that has me worried. Not sure if it's due to temp changes in the flue but I'm getting about half a cup full of a watery creosote drip from where the liner attaches to my adjustable 90. I realize now that I have the male/female connection backwards which is why I can see it drip but I'm guessing that much liquid dripping is abnormal. The liner is not insulated due to a tight flue with an offset. Just wasn't any way to insulate it. It does have a cap on the chimney though. Im just worried about creosote buildup. Have only been burning wood three days. I'm to the point already of calling the entire wood burning experiment a wash. Any input would be appreciated.
Fisher baby bear has me discouraged
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claydogg84
Minister of Fire
The pipe being backwards isn't helping. You shouldn't have all that much creosote built up in 3 days, so I'm wondering if it's actually water dripping down the pipe?
I plan on fixing the pipe connection tomorrow. The liquid that's dripping is very thin and watery. It's dark and smells like creosote though. I'm wondering if the hot flue cooling off could cause some condensation to form in the pipe. It was 18 degrees at my house this morning.
Welcome to the forums. If the wood is very dry and the stove burning hot, shutting the air supply to the fire may result in incomplete combustion. This was the case with many pre-EPA "airtight" stoves like the VC Defiant I grew up with. Not sure if it is the case with Fisher, too.
Are you closing off the air supply all the way? Do you have a thermometer a foot or so above the stove to measure flue temps? Is the chimney interior to the house (like a center chimney) or on an outside wall? If the wood is good, the problem may be a too-cool flue, either from a cold exterior chimney or an air-restricted fire not heating the flue enough.
Are you closing off the air supply all the way? Do you have a thermometer a foot or so above the stove to measure flue temps? Is the chimney interior to the house (like a center chimney) or on an outside wall? If the wood is good, the problem may be a too-cool flue, either from a cold exterior chimney or an air-restricted fire not heating the flue enough.
BTW, you probably could insulate that liner with loose perlite, although that may not be to code. You could also probably get some rock wool in around the very top of the liner. The chimney is sealed with a top plate where the liner exits the chimney, correct?
I agree with the others above. Things to check:
Temp of flue when this is happening.
Moisture content of a freshly split face of wood
Top plate installed at the top of chimney and it is sealed correctly
I would assume one or a combo of the above. Flue temps should be above 300 or so, higher the better. It's usually much higher on alot of stoves. This is an internal flue temp as measured with a probe. If its single wall pipe or a liner than the reading will be about half(if u read 200 the internal is 400 etc). If your liner is still shiny and your using an ir temp gun it may give a false reading. Paint a small area black with high temp stove paint or use charcoal to color it etc this will give a non reflective surface for accurate measurements with an ir gun.
I have a different stove, but for comparison my liner temp measures about 280 during an average startup, once i shut down the air in ranges from 200-240 but usually hangs around 225
Temp of flue when this is happening.
Moisture content of a freshly split face of wood
Top plate installed at the top of chimney and it is sealed correctly
I would assume one or a combo of the above. Flue temps should be above 300 or so, higher the better. It's usually much higher on alot of stoves. This is an internal flue temp as measured with a probe. If its single wall pipe or a liner than the reading will be about half(if u read 200 the internal is 400 etc). If your liner is still shiny and your using an ir temp gun it may give a false reading. Paint a small area black with high temp stove paint or use charcoal to color it etc this will give a non reflective surface for accurate measurements with an ir gun.
I have a different stove, but for comparison my liner temp measures about 280 during an average startup, once i shut down the air in ranges from 200-240 but usually hangs around 225
If your wood is dry (a big 'if' until it's tested with a meter on a freshly-split face,) I wonder if you are cutting back the air to try to stretch out your burn time. You really can't burn clean in the old stoves unless you have flame in there and the stove top is like 600°, otherwise you won't have the internal temps needed for clean combustion. That also keeps your flue temp up and prevents condensation, as has been mentioned. You are really going to chew through the wood in order to burn that old stove relatively cleanly. 
The newer EPA stoves (from mid-90s on) are able to burn cleaner with less air, thereby cutting wood usage. Your chimney also stays cleaner, as more of the pollutants are burned in the stove and never make it into the flue.
The newer EPA stoves (from mid-90s on) are able to burn cleaner with less air, thereby cutting wood usage. Your chimney also stays cleaner, as more of the pollutants are burned in the stove and never make it into the flue.My SILs' chimney caps have a stud through the top cover, and a wing nut secures the cover; I seal those with some silicone sealant after I've swept their chimneys, because I've seen those studs leak a bit of water down the inside of the pipe. It may or may not exit depending on how the stove is hooked up. In the OP's case I'm guessing the stove is top-vented, and the main source of his problem is the backwards connections.
Can you post a picture or two of the installation? There may be other safety issues that are wrong with this installation.
Is the stove original with no baffle plate added?
Is the liner 6 inch diameter? (expanding flue gas from 6 to 8 will cool and condense)
Are you using a pipe damper in the connector pipe? (condensing water vapor in flue is a sign to open damper)
What size area are you heating? (we need to verify you are sizing the stove correctly to heated area AND chimney)
In this thread you stated you have weak draft;
https://www.hearth.com/talk/threads/baffle-smoke-shelf-plate-size-for-fisher-baby-bear.149432/
If you already have a baffle plate that large, you are not leaving near enough heat up the chimney.
Water vapor is not only from moisture in wood. It is a byproduct of combustion. It is present with dry wood, oil or gas.
Is the liner 6 inch diameter? (expanding flue gas from 6 to 8 will cool and condense)
Are you using a pipe damper in the connector pipe? (condensing water vapor in flue is a sign to open damper)
What size area are you heating? (we need to verify you are sizing the stove correctly to heated area AND chimney)
In this thread you stated you have weak draft;
https://www.hearth.com/talk/threads/baffle-smoke-shelf-plate-size-for-fisher-baby-bear.149432/
If you already have a baffle plate that large, you are not leaving near enough heat up the chimney.
Water vapor is not only from moisture in wood. It is a byproduct of combustion. It is present with dry wood, oil or gas.
Sounds like wet wood .. Truly Kiln dried wood doesn't produce watery creosote even when the air is cut back . Your getting your water from somewhere and its most likely your wood
Dry wood perhaps doesn't produce watery creosote when the air is cut back in an EPA stove, because it is not airtight. But while dry wood does not have a high moisture content, it still has moisture content. Choke off ALL the air to a hot fire so it quickly cools, and feed the unburned gasses into a cold flue, and I think some of the resulting condensate could be liquid.
Depending on how much wood is burned and how effectively it is condensed, it most certainly can drip.
It is doubtful that the smaller Baby Bear can heat the original posters chimney flue of 24 feet in height.
With no insulation, or a larger flue size, it's not happening. That's why I asked for the square heated area to see if a larger stove can be used.
Jay Shelton's Woodburners Encyclopedia explains best, how much water vapor is produced ;
When burned completely, each pound of oven dry wood produces about .54 pound of water vapor. This is due to hydrogen content.
Wood with 25% moisture content produces another quarter pound of water vapor for each piece whose oven dry weight would be 1 pound. Total amount of water vapor produced from 25% moisture content wood is .79 pound which also represents 830 BTU of potential energy. (more BTU is actually required as it gets dryer since it takes more energy to break the bond between water and wood as the dryer it gets)
The basis of this formula gives you an idea of how much water vapor is created by the pound of oven dry wood.
Approximate composition of dry wood is 49% carbon, 44% oxygen, 6% hydrogen, 1% ash.
9 is the ratio of the molecular weight of water to hydrogen.
Every pound of hydrogen in oven dry wood becomes 9 pounds of water when completely burned.
Thus, 1 pound of oven dry wood with 6% hydrogen content produces .54 pounds water.
This equates to 10 pounds of oven dry wood producing almost 5 1/2 pounds water. Most is rising out of the chimney as water vapor, but condensed on the flue walls, it's not difficult to collect a half cup or more burning oven dry wood.
It is doubtful that the smaller Baby Bear can heat the original posters chimney flue of 24 feet in height.
With no insulation, or a larger flue size, it's not happening. That's why I asked for the square heated area to see if a larger stove can be used.
Jay Shelton's Woodburners Encyclopedia explains best, how much water vapor is produced ;
When burned completely, each pound of oven dry wood produces about .54 pound of water vapor. This is due to hydrogen content.
Wood with 25% moisture content produces another quarter pound of water vapor for each piece whose oven dry weight would be 1 pound. Total amount of water vapor produced from 25% moisture content wood is .79 pound which also represents 830 BTU of potential energy. (more BTU is actually required as it gets dryer since it takes more energy to break the bond between water and wood as the dryer it gets)
The basis of this formula gives you an idea of how much water vapor is created by the pound of oven dry wood.
Approximate composition of dry wood is 49% carbon, 44% oxygen, 6% hydrogen, 1% ash.
9 is the ratio of the molecular weight of water to hydrogen.
Every pound of hydrogen in oven dry wood becomes 9 pounds of water when completely burned.
Thus, 1 pound of oven dry wood with 6% hydrogen content produces .54 pounds water.
This equates to 10 pounds of oven dry wood producing almost 5 1/2 pounds water. Most is rising out of the chimney as water vapor, but condensed on the flue walls, it's not difficult to collect a half cup or more burning oven dry wood.
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