stoveliker
Minister of Fire
So, all, an update on my issue of not being able to even start the fire; newspaper even stopped burning.
Sweep came again. We took off all the stove pipe, lit newspaper in the thimble and in the flue liner. Smoke coming out in the basement, so no draft whatsoever.
But nothing wrong to see in the thimble. Nothing wrong to see down from the top. Screen of cap clean (had checked with binoculars too earlier). The next thing would be to order a chimney camera inspection to see if there would be a leak somewhere killing my draft (or leaving me with an effective "3 ft chimney" only
Sweep even threw in a small snowball (white), and saw it go down all the way, seeing it laying from the roof.
One thing is that the bottom of the liner seems to be a bit low, or there is no flue bottom (in the masonry external chimney).
As a last resort we shone a light up from the thimble, but - as you might have guessed, no light visible at the top. @bholler was right: the dropped flue liner (negative slope of the horizontal section) is not good, but could not cause the problem we had.
There was a blockage about 1.5 ft above the thimble.
How did we conclusively prove this? By using a laser distance meter ($40 at HD) outside and inside. Difference inside vs outside = blockage.
It appears the seed of this blockage had been there ever since I moved in this home. Likely the (yearly) sweep never got to the thimble sweeping from the top down, but bumped on this blockage, which initially had a hole that allowed me to burn. As it was very close to the thimble, he did not figure out that the length being swept was a bit too short.
Somehow it closed up. But when we pushed through from the bottom (through the thimble), half a 5 gallon bucket of dry crud came down. The flue (measured inside) is 27 ft tall.
Put everything back together (still the 90 degree and 2 ft horizontal run), the stove lit up like (what I understood to be) the "gates of hell". Man do I have a draft. Stove burns quicker (had secondaries going in 4 minutes top down, cat still below the inactive section of BK's probe). Even the window burned somewhat clean.
3 more minutes and the cat was active, closed the bypass. A total of 10 minutes in all was charred (Sassafras and one cherry), and I dialed down a bit. 37 F outside, almost no wind.
So, I will have the two 45's go in, go all double wall inside and decrease the horizontal run mid January - b/c it's better. Maybe I have to put in a damper, we'll see how it behaves in the time from now to then.
All in all, that blockage made sense from the observations. It's solved. Based on the way the stove took off just now, I firmly believe this was there already from the start (at least the start of the BK burning), although not closed off - it behaved like an old lady versus the racing heat machine it is now.
So I'll have to recalibrate my Tstat settings - but that's a play thing I gladly do over the Christmas break
Thank you all for your help, your thinking, for indulging my blindness in not recognizing the issue when it should have been obvious. This forum is invaluable.
I'm going to celebrate a warm Christmas.
