Anyone have good draw with a 1 story addition stove in a 2 story house?

[Poindexter]

I only read part of this becuase i got lost. My dad (now in Florida) had a house in upstate NY thay was built before 1776 with several "antebellum" additions. He was near Albany.

The facade faced east, with the youngest 1 story addition on the south side. He had a ridge behind him, to the west. Burnt about 10 cords annually.

The most efficient wood stove was at the south end of the south addition, but with a good ten feet of stack above the roof.

When is was cold enough to matter, -10, -20 F, that stove drew just fine. In the shoulders the draw was a bit finicky - but when I hear Jimmy Buffet singing about "the little latitudes" I think of mild climates like Boston and Fargo.

 

[Ashful]

I have a one-story addition on a FOUR story house, and a low-burning BK in the addition (as well as another in the main house). The addition is on the second level of the main house, so we might say effectively 1 story on 3 story.

The stove in the addition is on a chimney under 15 feet, and it still drafts just fine. My house was built in the 1770's, with original doors and windows throughout, so it's not tight.

The stove in the addition can be burned reliably at rates down to about 30 hours per 2.65 cubic feet. That's lower than any stove other than BK can run, but still not quite as low as my identical stove on 30 feet of chimney in the main house can run. If I turn down below this rate on the short chimney, the BK just stalls.

However, when I ran Jotuls, the stove in the addition used to back-puff at the lowest burn rate settings, a problem I never had on the tall chimney with the same model Jotul. So, the answer to "can it work?" will vary from one stove to another, and your low burn rate expectations.

 

[enigmablaze]

I only read part of this becuase i got lost. My dad (now in Florida) had a house in upstate NY thay was built before 1776 with several "antebellum" additions. He was near Albany.

The facade faced east, with the youngest 1 story addition on the south side. He had a ridge behind him, to the west. Burnt about 10 cords annually.

The most efficient wood stove was at the south end of the south addition, but with a good ten feet of stack above the roof.

When is was cold enough to matter, -10, -20 F, that stove drew just fine. In the shoulders the draw was a bit finicky - but when I hear Jimmy Buffet singing about "the little latitudes" I think of mild climates like Boston and Fargo.

Sounds like a cool house! In Illinois we don't often get to -20, our winters are more single digits and maybe -10 generally. I'd like to be able to use it in the fall and spring too of course. I assume even though it was "finicky" it still functioned?

 

[enigmablaze]

I have a one-story addition on a FOUR story house, and a low-burning BK in the addition (as well as another in the main house). The addition is on the second level of the main house, so we might say effectively 1 story on 3 story.

The stove in the addition is on a chimney under 15 feet, and it still drafts just fine. My house was built in the 1770's, with original doors and windows throughout, so it's not tight.

The stove in the addition can be burned reliably at rates down to about 30 hours per 2.65 cubic feet. That's lower than any stove other than BK can run, but still not quite as low as my identical stove on 30 feet of chimney in the main house can run. If I turn down below this rate on the short chimney, the BK just stalls.

However, when I ran Jotuls, the stove in the addition used to back-puff at the lowest burn rate settings, a problem I never had on the tall chimney with the same model Jotul. So, the answer to "can it work?" will vary from one stove to another, and your low burn rate expectations.

This is good, really helpful, thank you. So your direct comparisons always showed the ideal installation as superior to the addition installation but (I assume) the addition stove is still worthwhile and enjoyable to you, with your understanding of its limitations? Is that fair? And is that under 15 feet of chimney altogether starting at the stovetop or is the 15' above the roof?
Is back-puffing scary? This article (http://www.woodheat.org/case-study-the-terrifying-hot-backdraft.html) about hot backdraft confused me a bit on what it even is, is it dangerous? ETA, I just re-looked over that article, I still don't know what a hot backdraft is for sure but apparently it can fill the house with Co2...so obviously dangerous whatever it is.

Your house sounds absolutely beautiful, I remember maybe a year ago looking at pictures of your Jotuls I think on here

 

[Ashful]

Enigmablaze,

Yes, your take on the addition is correct, still worth having.

Backpuffing can be a little unnerving, but mine never got to the real violent level. It was merely annoying to us, as it would make the house smell like stale stove smoke. We could make it stop by just opening the air a hair, if we were home when it happened.

 

[Poindexter]

Finicky, functioned. The "trick" is evaluating your local prevailing air currents.

I am sure you are going to meet or exceed federal code for chimney, the elephant in the room is how much "extra" pipe will you need at your location to get good draft most of the time.

I would start with the minimum required to meet code and install guidelines. If the installer says, hey with this set of brackets you need anyway you can actually carry another 18" of pipe, i would probably max out the height right then to save paying the installer to drive out a second time.

If that isnt enough you are going to need different brackets to support more pipe.

 

[Ashful]

I should have mentioned a few other things.

First, I only had backpuffing issues with my Jotuls, and I believe the reason is that they had far too small a catalytic combustor, for the size of the firebox on that old stove design. The combustor in that stove was almost exactly half the size (cross section vs. cubic feet of firebox) of any modern Blaze King or Woodstock combustor. That stove, like many cat stoves of its vintage, had a fresh cold air intake feeding the combustor, which did not throttle along with the primary air into the firebox. This combination of factors seemed to cause the backpuffing, along with sometimes out-of-control combustor temperatures. My Blaze Kings have never back-puffed, and I turn them down much, much farther than the Jotuls could even go.

Second, the overwhelmingly most common complaint from those switching from older stoves to modern EPA non-cats, is that they don't draft well. That's because most non-cats don't have a bypass mechanism to aide in getting the fire going, under low-draft conditions. This is where cat stoves are different, as you always open a bypass which provides a straight shot from firebox up the chimney, to get the fire started and up to temperature, before closing the bypass to force exhaust thru the combustor. So, while you may not be able to take full advantage of one of the cat stove's best attributes, that being an ability to turn way down for ultra-low burn rates, I believe the cat stove is still the better option for those with marginal draft.

My shorter chimney is most often completely stalled when cold, if not reversed. Thanks to the bypass in the cat stoves, I can hold a lit fire starter (or even a hairdryer) right under the stove pipe opening, and warm the chimney very quickly. This gets draft going the right direction, before lighting the fire. Once I get the draft going in the right direction, it continues to work throughout the burn, and for probably a day after the stove has gone out (thanks to remaining a little warm for a long time after the fire is out).

 

[Seasoned Oak]

Size matters.my son has a NC-30 on a 2 story brand new chimney. While my NC-30 is on a old chimney with a 12" flue. Mine works fine but its not the thermal beast that the one on the tall new chimney is. That stove can go to 900 degrees quickly ,where mine tops out at about 650.

 

[BKVP]

I should have mentioned a few other things.

First, I only had backpuffing issues with my Jotuls, and I believe the reason is that they had far too small a catalytic combustor, for the size of the firebox on that old stove design. The combustor in that stove was almost exactly half the size (cross section vs. cubic feet of firebox) of any modern Blaze King or Woodstock combustor. That stove, like many cat stoves of its vintage, had a fresh cold air intake feeding the combustor, which did not throttle along with the primary air into the firebox. This combination of factors seemed to cause the backpuffing, along with sometimes out-of-control combustor temperatures. My Blaze Kings have never back-puffed, and I turn them down much, much farther than the Jotuls could even go.

Second, the overwhelmingly most common complaint from those switching from older stoves to modern EPA non-cats, is that they don't draft well. That's because most non-cats don't have a bypass mechanism to aide in getting the fire going, under low-draft conditions. This is where cat stoves are different, as you always open a bypass which provides a straight shot from firebox up the chimney, to get the fire started and up to temperature, before closing the bypass to force exhaust thru the combustor. So, while you may not be able to take full advantage of one of the cat stove's best attributes, that being an ability to turn way down for ultra-low burn rates, I believe the cat stove is still the better option for those with marginal draft.

My shorter chimney is most often completely stalled when cold, if not reversed. Thanks to the bypass in the cat stoves, I can hold a lit fire starter (or even a hairdryer) right under the stove pipe opening, and warm the chimney very quickly. This gets draft going the right direction, before lighting the fire. Once I get the draft going in the right direction, it continues to work throughout the burn, and for probably a day after the stove has gone out (thanks to remaining a little warm for a long time after the fire is out).

Ashful....there are a couple non catalytic stoves with bypasses....

 

[BKVP]

Ashful....there are a couple non catalytic stoves with bypasses....

Sorry...just read you did say "most".

 

[begreen]

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.

 

[enigmablaze]

I should have mentioned a few other things.

First, I only had backpuffing issues with my Jotuls, and I believe the reason is that they had far too small a catalytic combustor, for the size of the firebox on that old stove design. The combustor in that stove was almost exactly half the size (cross section vs. cubic feet of firebox) of any modern Blaze King or Woodstock combustor. That stove, like many cat stoves of its vintage, had a fresh cold air intake feeding the combustor, which did not throttle along with the primary air into the firebox. This combination of factors seemed to cause the backpuffing, along with sometimes out-of-control combustor temperatures. My Blaze Kings have never back-puffed, and I turn them down much, much farther than the Jotuls could even go.

Second, the overwhelmingly most common complaint from those switching from older stoves to modern EPA non-cats, is that they don't draft well. That's because most non-cats don't have a bypass mechanism to aide in getting the fire going, under low-draft conditions. This is where cat stoves are different, as you always open a bypass which provides a straight shot from firebox up the chimney, to get the fire started and up to temperature, before closing the bypass to force exhaust thru the combustor. So, while you may not be able to take full advantage of one of the cat stove's best attributes, that being an ability to turn way down for ultra-low burn rates, I believe the cat stove is still the better option for those with marginal draft.

My shorter chimney is most often completely stalled when cold, if not reversed. Thanks to the bypass in the cat stoves, I can hold a lit fire starter (or even a hairdryer) right under the stove pipe opening, and warm the chimney very quickly. This gets draft going the right direction, before lighting the fire. Once I get the draft going in the right direction, it continues to work throughout the burn, and for probably a day after the stove has gone out (thanks to remaining a little warm for a long time after the fire is out).

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?

 

[enigmablaze]

Finicky, functioned. The "trick" is evaluating your local prevailing air currents.

I am sure you are going to meet or exceed federal code for chimney, the elephant in the room is how much "extra" pipe will you need at your location to get good draft most of the time.

I would start with the minimum required to meet code and install guidelines. If the installer says, hey with this set of brackets you need anyway you can actually carry another 18" of pipe, i would probably max out the height right then to save paying the installer to drive out a second time.

If that isnt enough you are going to need different brackets to support more pipe.

Am I correct that you need a roof bracket every 5 feet? So If we did, say, 9.5' above the roof we would only need one bracket? That's a pretty expensive piece.

 

[enigmablaze]

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.

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.

 

[bholler]

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.

No that is not a back puff at all. A back puff happens when to much smoke builds up in the firebox then it ignites causing a small explosion.

 

[enigmablaze]

My shorter chimney is most often completely stalled when cold, if not reversed. Thanks to the bypass in the cat stoves, I can hold a lit fire starter (or even a hairdryer) right under the stove pipe opening, and warm the chimney very quickly. This gets draft going the right direction, before lighting the fire. Once I get the draft going in the right direction, it continues to work throughout the burn, and for probably a day after the stove has gone out (thanks to remaining a little warm for a long time after the fire is out).

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?

 

[enigmablaze]

No that is not a back puff at all. A back puff happens when to much smoke builds up in the firebox then it ignites causing a small explosion.

Oh, well I can see why that would be dramatic then. I assume that stoves generally contain this explosion? I mean, it doesn't generally damage them does it?

 

[bholler]

Oh, well I can see why that would be dramatic then. I assume that stoves generally contain this explosion? I mean, it doesn't generally damage them does it?

No damage is very rare

 

[BKVP]

Delayed ignition can often be associated with a very hot fire and then cutting back on the air. The best method to avoid the occurrence is to make gradual or incremental air setting changes.

 

[enigmablaze]

No damage is very rare

What is the "cure" to a stove prone to this? Will taller pipe generally help it?

 

[enigmablaze]

Delayed ignition can often be associated with a very hot fire and then cutting back on the air. The best method to avoid the occurrence is to make gradual or incremental air setting changes.

Is "Delayed ignition" the same as a back puff?

 

[BKVP]

Is "Delayed ignition" the same as a back puff?

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.

I don't think it is really frequent but can be induced. I found it really easy to induce when using manufactured fuels, noted for being 7% or less in mc.

I also have found in isolated cases where someone would come down stairs or come home to a house smelling of wood smoke, video surveillance has shown the culprit waz was a delayed ignition (back puffing).

 

[Poindexter]

When the wind was "just wrong" at my dad's old place he would just burn a half load wide open instead of trying to run a full load at half throttle.

 

[Ashful]

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.

 

[begreen]

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.

Some stove designs are more draft sensitive and can be more prone to backpuffing when draft is marginal. VC downdraft models are another example. But backpuffing can also happen due to operator error. For example, if damp or poorly seasoned wood is place on a kindling fire (or turns down the air too soon) and that causes the fire to temporarily go out so that smoke builds up. Then the operator unwittingly supplies more air to the fire that causes a flame to appear and ignite the unburnt gases. Don't ask how I know this, but it involved a Jotul Castine. Not the stove's fault at all. We get a few inquiries every year where this happens.