Fireview Backpuffing?

[RandyG]

Strange thing happened this morning,well strange to me anyway, I reloaded this morning at 175 stovetop, just put 3 to 4 smaller splits in, mix of oak and maple to get things going again, though not to much because supposed to warm up a bit today, and got a pretty fast flame going again, slowly worked the damper down as the stove top rose to 250. As normal hit 250 in approx 35min, set damper to 1 and engaged cat. Thought I would get in the recliner and catch a little more sleep before the wife got up and I was just drifting off when the faint smell of smoke awakened me, I got up and looked at the stove and couldn't see any smoke escaping anywhere so for a second or two I was scratching my head until all of a sudden "WOOF" sound came from the stove and a puff of smoke came from underneath the top on all sides, also at this same instant a large flame filled the firebox and then was gone. It was doing this about every 15 secs. I wasn't sure what was going on, this has never happened before, the only think I could think of I had done differently was I usually set the damper to around .75 when cat is engaged and this morning I set it to 1. So I just inched the damper down to about .50 and I that seemed to fix it. After about 10 min I adjusted back to .75 and now all seems well. I just would like some explanation of this phenomena. I have heard about this condition but just have never seen it myself, really strange. Oh, house temp 71 and outside temp 44, thanks. :gulp:

 

[Todd]

I've had that happen a few times but usually it's because I turn the air down too soon too much. From what I hear it's caused by a gas build up in the fire box and when the cat gets hot enough it will light off the gas and WHOOF! Sometimes the exhaust can't handle the volume and will find another outlet like the top lid.

Seems like your waiting a long time to engage? Is this from a cold start or reload? I think you could easily get away with engaging at 200 stove top. I've engaged from a cold start with stove top temps in the 150 range but I also monitor the cat and pipe temps and have the new steel cat.

 

[RandyG]

First of all thanks for chiming in Todd, this was a reload from last night not a cold start and its interesting that you have engaged cat at low temps, I too have the ss cat but always thought you had to wait until at least 250 to engage, even on reloads. I'm glad you have told me that because I have been thinking it somewhat of a pain to wait around for 250. I've just been trying to go by the manual and handling it with kid gloves you might say. I'm going to try your method next time with a faster engage, just was afraid of damaging the cat.Thanks again....

 

[Backwoods Savage]

Randy, do you have a flue thermometer? The reason for asking is that sometimes our stovetop will be well up to temperature but not so with the flue. By using both, we've had good luck.

As for the back puffing, this can be common no matter what the stove. Basically it is starved for air or the temperature of the flue is not high enough and the smoke and gasses get locked in the chimney until there is a mini explosion, which is what you were seeing. Usually giving the stove more air will stop this.

If your wood is right you should have no worries of damaging the cat.

 

[fire_man]

Randy:

Your post got me thinking: We have an uninsulated 6" SS flue running through a clay liner. When we first got our Progress, the entire chimney was stone cold. The first two days of operating the Progress, after we loaded the stove and first lowered the draft, I got the huge "WOOFS" you are talking about. Since then, the chimney has been in constant use, and with outside temps the same as when the stove previously backpuffed (40 degrees) we now no longer get the backpuffing. I am thinking the SS liner warmed the clay liner, so I got a better draft and no more backpuffing.

Does anybody have any thoughts on this? I wonder if I would be preventing that nice thermal masonry mass from warming, and draft might suffer?

I mention this because I was intending to insulate the liner next spring, but I wonder if that would prevent the masonry chimney from warming up, and I would actually make backpuffing worse?

In your case, it's strange because you were giving the stove more air than usual, and you were reloading the stove so the flue was probably already very warm. What kind of flue settup do you have? If the cat was clogged, that might cause backpuffing.

 

[Backwoods Savage]

Tony, the insulation should take care of the problem. Good to hear you no longer get it but no doubt it will be back in the spring until you get it insulated.

 

[jdonna]

Randy,

One thing comes to mind as well, check which direction the wind is coming from and the wind speed speed as well. Some people suffer from wind induced down drafts which can cause backpuffing as well.

I have had a few woofs with mine as well. I echo what Todd and Backwoods said, usually from oxygen starvation and opening up the air the air for a bit is the cure and then backing it down.

Are you running the Stainless Steel Scoop by chance? Maybe check to see if it is getting restricted from fly ash.

For me setting the air and the way I load the stove is dynamic to air temp and wind speed/direction.

 

[fire_man]

Tony, the insulation should take care of the problem. Good to hear you no longer get it but no doubt it will be back in the spring until you get it insulated.

Dennis: That's what I was thinking: Spring will become a problem again since the chimney will cool off between fires. I would imagine in a Florida climate that insulating your chimney would be really important.

 

[rkshed]

I had this problem with my wicked old Garrison II this fall. Installed fatter door gaskets and problem solved.
1 degree last night and 68 inside this morning. Good stuff.

 

[Gark]

Randy- our setup tends to backpuff in moderate outside temps (like 44 degrees) but not when temps get colder (30 or less). I guess the better draft that happens when it's cold out pulls the smoke from the firebox faster (through the cat), so it can't build up and spontaneously light off (WHOOF!). By setting the primary air to get at least a little firebox flame, that helps too.

 

[RandyG]

Randy, do you have a flue thermometer? The reason for asking is that sometimes our stovetop will be well up to temperature but not so with the flue. By using both, we've had good luck.

As for the back puffing, this can be common no matter what the stove. Basically it is starved for air or the temperature of the flue is not high enough and the smoke and gasses get locked in the chimney until there is a mini explosion, which is what you were seeing. Usually giving the stove more air will stop this.

If your wood is right you should have no worries of damaging the cat.

Dennis. I have a flue therm as well as a stove pipe therm on my connector pipe to monitor upper stack temps at a glance, and I watch these pretty closely as well as an ir gun. My stack temps this morning were pretty low come to think about it and this could have had somthing to do with it. If my stack temp is low and my stovetop is 250 or above, should I wait to engage utill the stack comes up? I have 12 ft of ss chimney pipe and all but 2' 9" is in my attic. I have 6-12 pitch and a large attic. Two 90 's in my stove pipe as my stove is just a bit off center from my peak. The weird thing is, I actually reduced the damper this morning from 1 to .50 to stop the backpuffing, contrary to what I'm hearing which is to increase the damper. Going to have one more cool night tonite so going to see if it does it again, could have just been the perfect storm. Thanks to all for your input and support. :coolsmile:

 

[Backwoods Savage]

Randy, sorry this took so long to answer.

Not sure what your stack temps are but we usually run around 250-350. However, with the stovetop only at 250 then the flue definitely will be cool; probably below 250. For engaging, try for 400 (external) on the flue temperature before engaging but also go by stove top. But we find many times the stove top will be up to temperature but the flue lagging. For these times we just wait for 400 degrees to engage and it seems to work well. That is interesting that you are cutting the air and it is stopping the backpuff. But if it works, don't try to fix it. lol

 

[jdonna]

Just for a reference Dennis, you are running single wall stove pipe I am assuming? How tall of a stack are you running from the collar up?

 

[Backwoods Savage]

Yes, single wall. Our chimney is super short! In fact, when we put up the new chimney I had it higher but after doing some checking of the draft, took off some and returned it for a refund. We have had no problems with it but I still won't recommend it to others. Height is only about 12' and one 90 degree (the tee).

 

[Woody Stover]

I've got a stove top meter, cat probe and external flue thermo which rests on the horizontal stainless tee takeoff directly behind the flue collar. Before the cat is engaged, the cat probe serves to monitor the fire box temp. The cat probe and flue meter generally shadow each other except when I'm bringing the stove temp up relatively quickly...then the flue temp will lag a little bit. When starting cold or reloading, if I bring the cat probe up to about 900-1000 and the flue is about 500 or above, I'll maintain that level for about 10 minutes and then I can engage the cat and it will light off even if the stove top is still below 200. When the stove is cruising at 450 or so the cat probe will read about 1000. That probe is about 8" long so the actual cat temp at the tip of the probe gets diluted before it reaches the spring end. The actual cat temp is considerably higher. A setup like Todd's where he drilled down through the top of the stove and has a shorter probe gives a more accurate cat temp.

 

[RandyG]

My problem is I really cannot fully load the stove to capacity as you guys do because of milder temps outside. I generally put about 4 to 5 medium sized splits in at a time and usually heat all night on that. I actually only hit 500 on my stove top briefly a week or so ago when it got down in the 20's one night for the first time. With this in mind I only can usually get about 300 to 350 stack temps before engaging just because of the amount of wood I'm putting in the stove. I have a well insulated house and most times have windows open in stove room just to keep temps comfortable. I have even gotten desperate a few times this yr and cranked up the attic fan to cool the house just so I can light up, yes I have it bad. Anyway its going to be difficult for me to get the stack temps up like I should. I had a fire the night after this post and all went well, however that evening I made it a point to make sure me stack temps were up a bit, this must be the problem. I'll have to pay closer attention to this from now on. Thanks again everyone, cheers!! ;-)

 

[Stump_Branch]

I've got a stove top meter, cat probe and external flue thermo which rests on the horizontal stainless tee takeoff directly behind the flue collar. Before the cat is engaged, the cat probe serves to monitor the fire box temp. The cat probe and flue meter generally shadow each other except when I'm bringing the stove temp up relatively quickly...then the flue temp will lag a little bit. When starting cold or reloading, if I bring the cat probe up to about 900-1000 and the flue is about 500 or above, I'll maintain that level for about 10 minutes and then I can engage the cat and it will light off even if the stove top is still below 200. When the stove is cruising at 450 or so the cat probe will read about 1000. That probe is about 8" long so the actual cat temp at the tip of the probe gets diluted before it reaches the spring end. The actual cat temp is considerably higher. A setup like Todd's where he drilled down through the top of the stove and has a shorter probe gives a more accurate cat temp.

Woody, i have a very similar flue probe setup. I would love to have a cat probe but it would be hard for me to ever see it without a mirror of sorts. Is your probe off to one side of the cat or did you bend it a bit? Shame a tel-tru style with the element in the shaft doesnt exist for this application.

Todds is the nicest looking, best functioning setup, but i think the keystones reversable flue collar, and cat placement make it ideal. I wouldnt mind putting a hole in the top of the fireview, but it would be off center due to the cast piece, and that doesnt look right in me eyes.

Any better ideas?

 

[Todd]

The cat probe does give you some good info and I'm the kind of guy that likes to tinker with these stoves to find out what makes them tick but I don't think a cat probe is an essential tool for these stoves. You can get most of info you need from a flue probe and it's much easier to sit on the couch and look over at the stack than get up off my lazy duff to check the cat probe. Lately I haven't used the cat probe and plugged the hole in the top vent plate so I can set a steamer on top to help with humidity, but it's nice to know I can switch back and forth when I want.

As far as the Fireview goes I was real tempted to drill down through the top with mine but I also think it may not look right off to one side or the other. I think it would be better to hook up some kind of thermocouple through the back and have a digital readout hanging where you can see it. Condar sells one but I think the probe is a bit too short of the cat. You need to get it within 1/2" of the cat.

 

[Stump_Branch]

Much too my wifes dismay i enjoy these things too much as well. Mostly because theres other projects which need attending too.
I will research some thermo couple options. I just like the analog look better than digital, go figure.

Did get the wife to like soapstone enough to get an island countertop made from it, part of the aforementioned projects..

 

[Todd]

Much too my wifes dismay i enjoy these things too much as well. Mostly because theres other projects which need attending too.
I will research some thermo couple options. I just like the analog look better than digital, go figure.

Did get the wife to like soapstone enough to get an island countertop made from it, part of the aforementioned projects..

If you come up with something let me know.

 

[Backwoods Savage]

My problem is I really cannot fully load the stove to capacity as you guys do because of milder temps outside. I generally put about 4 to 5 medium sized splits in at a time and usually heat all night on that. I actually only hit 500 on my stove top briefly a week or so ago when it got down in the 20's one night for the first time. With this in mind I only can usually get about 300 to 350 stack temps before engaging just because of the amount of wood I'm putting in the stove. I have a well insulated house and most times have windows open in stove room just to keep temps comfortable. I have even gotten desperate a few times this yr and cranked up the attic fan to cool the house just so I can light up, yes I have it bad. Anyway its going to be difficult for me to get the stack temps up like I should. I had a fire the night after this post and all went well, however that evening I made it a point to make sure me stack temps were up a bit, this must be the problem. I'll have to pay closer attention to this from now on. Thanks again everyone, cheers!! ;-)

Randy, it is still a puzzle to me why you don't get the higher flue temperatures. If we load with 3 or 4 medium splits we have no problem getting up to temperature and then when we engage the cat the stove easily goes over 500. It doesn't take a whole lot to get our stove up to the 600 degree range either and does not require a full load. Case in point is today with a high temperature of 23, around 1:00 pm the stove was down to coals so we added 3 splits. Temperature when I left the house a short time later was 620.

 

[fire_man]

I can chime in on this one. I was having trouble getting my FV stovetop much over 400 for the first season of use. During the second season I was on the phone with WS to ask them why I was constantly hitting 700 F stovetop temps, and should I worry?! Turns out my Beech splits were finally nice and dry, and since they were split on the small side, led to very hot stove temps. It's all in the wood!

 

[RandyG]

I can chime in on this one. I was having trouble getting my FV stovetop much over 400 for the first season of use. During the second season I was on the phone with WS to ask them why I was constantly hitting 700 F stovetop temps, and should I worry?! Turns out my Beech splits were finally nice and dry, and since they were split on the small side, led to very hot stove temps. It's all in the wood!

Tony, I think you hit the nail on the head on this one, 9 month c/s/s maple is the driest wood I have this season, and although it reads 15% on the moisture meter there's just no way its as dry as Dennis's wood which has been seasoning for several yrs. I just stacked a bunch of live oak which is about the best hardwood we have down here so I'm like you in thinking that next yr I'm going to have a totally differently behaving stove. One of the reasons I don't think my wood is totally there yet, along with lower stack and stovetop temps, is that my glass is not totally staying clear. I usually have to clean it about every two fires and I know that's not normal with this stove and is a sign of not totally seasoned wood. I'm pretty sure I'm in the same boat your were in last yr. Thanks, and Dennis, do you think this is the case?

 

[fire_man]

Randy:

Sooty glass after just a couple fires is a dead give away that the wood is not seasoned enough. Let's see if Dennis agrees on this one.
The oak might take 2 or 3 years to dry, even in Florida. I agree, your stove will act like a completely different animal next year with dryer wood.

From the sounds of how excited you are running this stove, I think you need to move up north with the rest of the FV crew!

 

[RandyG]

Randy:

Sooty glass after just a couple fires is a dead give away that the wood is not seasoned enough. Let's see if Dennis agrees on this one.
The oak might take 2 or 3 years to dry, even in Florida. I agree, your stove will act like a completely different animal next year with dryer wood.

From the sounds of how excited you are running this stove, I think you need to move up north with the rest of the FV crew!

Tony, you are so right. I would fit right in and love it! I was definitely born in the wrong place, I'll make it up there one of these days, its my plan anyway!! Would love the long burning season for sure. ;-) And now I'm certain my problem is the fuel!! Thanks!!