Smoke out the back of the Ashford...

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Dec 2, 2018
Greetings All,

Last night, I reloaded the BK Ashford, went through the typical process- bypass damper open, for a few minutes, crack the door for a few minutes, then reloaded 4 splits of red fir. Let it burn w the door open about 10 minutes, close the door, burn another 10 minutes or so (cat temperature probe about 1/3 in the ignited zone) and then closed the bypass damper. Within a few seconds, smoke was billowing out the back of my stove... and the fire died down lik eit was being smothered. My cat wasnt glowing red. thermostat was on maximum heat.
I opened the bypass damper and the smoke stopped rolling out the back. I opened and closed the bypass several times and tried again... same response x 2.
at this point, I open the bypass damper, manipulated the thermostat setting to be on half heat until I heard the bivalve close and let the Stove run for about 20 minutes. The cat heated up a little more I then tried it again following the same method as above and I did not have smoke out of the back. The cat was not glowing red and the fire died down tremendously. No smoke was coming out of the back and after about 30 minutes the cat temperature probe started rising and was moving about halfway and I started to see flames in the fire box. no smoke was coming out of the back I let it run wide open for about 30 minutes and now this dose seems to be functioning for last night's burn. I do not plan on using it again until I get a chance to really inspect things. In the end, with the cat temperature probe it was in the two thirds burn range and the cat red except for a couple of small spots that were dark and that seemed to shift depending on where the flames were coming from in the fire box. Last night burn eventually seemed to normal and I woke up this morning to a non-smoking house with the coals burned down as expected. I typically load the stove twice daily.

so my thoughts on this initially were ...
1. I should get on the roof and look the cap- however if the cap was the problem then it probably would not have drafted very well when I opened the bypass damper and when I did open the bypass damper the fire box came alive very quickly.
2. Obstruction at the bypass damper- then it occurred to me and obstruction would make it so that the fire box stayed alive because it would still be bypassing the cat resulting in improved airflow
3. possibly a plugged cat… initially, the cat was not glowing but the temperature probe indicated it was in the burn zone. Perhaps it was not hot enough to burn off any soot. We burn mostly red fir, some white fir, and some pine- because we have a lot of it on our property. I do not have a moisture meter (i know... I know...) but the would had been cut stacked for several months and was from a log pile that had been demarked and sitting for years.
regardless of the culprit, how is it that in a sealed box with no smoke coming out of the front of the stove that I had smoke visibly spilling out of the back of my stove? The stove was exiting out the back seemingly adjacent to the rear box enclosing the by a metallic valve air intake. I took a video of this. Initially a lot of smoke spilled out but as the stove was heating up less smoke was coming out but I was able to capture this.

Any ideas on where I should look? any ideas on why smoke would be able to exit the rear of the stove. The stove has not been moved, bumped, or anything along those lines. It does have a cold air intake which is running from the crawl space of the house.
Your opinions are appreciated.
I attached a photo of the smoke out the back. I couldnt tell where it was coming from.

Smoke out the back of the Ashford...
You have the right order of inspection. Start with the cap and the upper part of the chimney. Check for build-up and plugging.

Can you describe the flue system in detail? What is the stovepipe routing? Any elbows or tees? How does it connect to the chimney? Is the chimney interior or exterior? Metal or masonry?

If the stove vents into a tee, check there for build up too.
Flue is excel dbl wall stove pipe- 36 inch straight run, 2-45s and then the ceiling support box and excel stainless chimney with down draft preventing cap. The avatar is a picture of the system. total length about 17+ ft. Elevation 3200-3300 ft. On a hillside w a significant downdraft due to elevation and large trees 50+ feet tall behind the house. I find that I need to burn the stove hotter to keep the draft up. elbows are needed to avoid the truss above the stove.
That's a good setup. If behavior changes with you doing nothing, then it's possible that this could be atmospherics and/or possibly the relationship of the chimney to the roof. Some chimney locations can become a high-pressure zone when the wind is blowing from a certain direction.
I'll be on the roof tomorrow looking. Again though where would the smoke be coming from??? Possibly the flue collar and wxiting the rear due to airflow in the stove heath area?
I'll be on the roof tomorrow looking. Again though where would the smoke be coming from??? Possibly the flue collar and wxiting the rear due to airflow in the stove heath area?
If your stove is backing up and unable to exhaust smoke it can back up into the intake system. Even though you have an oak connection that intake system contains loose fitting connections. The curved hood over the thermostat is a loose fit, the oak plate near the bottom is a loose fit. Yes, the flue connection can be quite leaky too if your chosen pipe is a poor fit. The only other openings are the loading door and ash plug. I suppose a small leak is possible where the cat meter probe enters the stove too.
There was nothing out of the ordinary. Atmospheric anomaly, too much creosote in the fire box or a combination of both, don't know but it hasn't happened again. Its been colder lately and the stove has been ran hotter cleaning up the glass and the firebox creosote. It is drafting well, running properly, and there is NO smoke on a reloading. I think that I'll make a habit of running it for 20 minutes on high airintake prior to shutting it down for a cruising burn.
Thank you again.