Backpuffing can occur with almost any stove. The degree of backpuff will vary with the amount of unburnt gases collecting in the stove without the presence of flame. With air introduced and a flame, the resulting backpuff can be anything from minor to something very dramatic.
I guess it can occur with any stove, but some stoves are definitely more prone to it, than others. I do believe the Jotul Firelight 12 is one of these stoves, for the reasons I already mentioned. I also remember several owners of one of the Woodstock stoves (Fireview?) having issues with backpuffing. I don't think other stoves are as likely to exhibit this issue, unless something is lacking in the installation.
Well the Morso 1440 is an EPA non-cat so I'm guessing it would perform more like your Jotuls. Do you think the small size would make it perform worse? Is that what you meant about the combustor size in the Jotuls?
The old Jotuls to which I'm referring were early catalytic stoves, designed 30 years ago, at a time when perhaps less was understood on how to design a good catalytic stove. When I say the combustor was small, I mean the catalytic combustor had a cross section under 8 sq.in. per cubic foot of firebox volume, whereas any modern Woodstock or Blaze King has about twice the combustor cross section per unit volume of firebox.
So, if I understand correctly, back puffing can happen when the flames have died down, the draft collapses and air is drawn into the stove instead of up the chimney, thus sending Co2 gas that was not consumed from the coals into the house?
So do you SEE this happen? Or just smell smoke? Obviously this is one reason CO2 detectors would be important. I am wondering what a "dramatic" backpuff would look like.
In my stove, you would typically see a flash from the firebox, and then hear and see it wheezing smoke out thru the air intakes. It happens when you have a hot firebox (or exposed combustor), and draft or burn rate too slow to keep the combustible products moving through the system at sufficient rate. The volatile wood gas and intake air mix in the firebox, contact an ignition source (anything hot in the stove), and go puff. This rapidly uses up all available fuel and oxygen, and stalls the stoves. But the wood is still producing wood gas, which immediately begins to accumulate again. Eventually the warm chimney causes enough fresh air to be drawn in thru the intake again, and the cycle repeats.
A dramatic backpuff can blow the doors open, but I've never seen one anywhere near that, and think that's exceedingly rare. I heard of it happening to a friend of a friend once, around 30 years ago...
The dealer we are planning on picking up the Morso from mentioned these techniques as well for getting the draft going. My concern is, while this would get the draft going for the majority of the fire, what happens when the fire dies down and the draft goes away? Would that mean a back puff would happen all the time or does the residual heat from the chimney pipe usually keep the draft strong enough to avoid this until the coals are died down?
I guess, is back puffing a common issue that would happen routinely with this setup or is it something that happens every once in a while in the wrong wind etc?
I have never seen draft reversal on a warm stove. In my (limited) experience, the residual heat is always enough to keep draft working properly, well after the fire has gone out. In fact, draft reversal is not normally a problem in winter, when temperature difference between inside and outside is substantial.
What is the "cure" to a stove prone to this? Will taller pipe generally help it?
Backpuffing is mostly on an issue when trying to burn at very low rates on too-short chimneys. The cure, if your installation suffers from this, is to open the intake air a little or extend your chimney. Most people with this issue find it easier to just take note of how low they can turn down the stove, for a given outside temperature.
Yes, I think you could call it back puffing.
I have worked the past three years trying to cause delayed ignitions. I have found, as I posted earlier, rapid air settings changes, excessively dry fuel and insufficient draft can all contribute to the occurrence.
Some woods seem to favor it. There was a period, post-Sandy, when I was burning a lot of Walnut. I found that full loads of Walnut seemed more likely to cause back-puffing, than other species.
