Too much draft causing VC Acclaim secondary overfire?

[Kobeman]

Hello all. So I finally got my resolute acclaim all rebuilt and the chimney installed, got my break in fires done, so tonight I thought I'd load er up a bit more. Some details about my system. Double wall connector 3' up, 90 through wall,, then 21' straight up side of house chimney. Its 15-20 mph winds here tonight about 45 deg.. So stove was doing well, built up a coal bed and reloaded, let it burn a bit, I have a stove top thermometer and it read 400 so I closed damper, got air dialed in to get 450 on griddle, after a bit I noticed paint smoke from back of stove, laser thermometer said 700 on stove back, shut primary air off and I could still hear the secondaries like a blast furnace so i bent a piece of sheet metal and covered up secondary air inlet to get it under control. So, I believe the wind caused an overdraft. Question is without adjustible secondary air on this stove, is a damper in order here? also if I do put in a damper how will I know best settings on it? Would I have seen this high secondary burn rate on a stove pipe probe thermometer? I'd appreciate any advice on this, thanks!

 

[Oldhippie]

I have one, and before I replaced the combustor (I bought it used) I had similar problems, now that I have a new combustor I don't get the overfires, but I do still use a flue pipe damper as well, but usually leave it in the wide open mode.

It makes me wonder if you are sure your main air feed is closed all the way. Have you gotten down on the floor and checked to make sure the primary air is actually closing when you move the lever? ...and it's tight and all that?

I have a similar chimney set up, actually I've got a center chimney in the house but it's a basement stove and has a full 26 feet of chimney. If you do go with a damper it's a simple matter of trial and error.. to get the right settings for it.

PS you'll probably get some paint smoke with a full fire if you just painted the stove. ...and the top griddle and the back of the stove will easily climb to 700 if you have a full fire going but the flue temp with a magnetic flue thermometer will be less. ..at least it is for me.

You did replace the combustor, right?

 

[Kobeman]

I did not replace the combustor, It seemed ok, I thought I'd run it for a year, Guess I'd better order one if you think its needed. I bought this used, knocked it apart, new top, as it was warped, all new gaskets, and resealed it all, I can control the main firebox with ease, throw lever to the left and the flames immediately go out, go right and the coals glow. Butterfly is closing I checked, once i choked the secondary air out, it calmed right down. Thought I was keeping a close eye on it with the thermometer on the griddle but it stayed around 450 while the back was 700. Do you usually have to worry about the rear getting too hot? My big fear now is if i'm not in the house and the wind picks up and the damned thing runs away, frustrating after all the work i just did to it.

 

[branchburner]

This is an Everburn, correct? If so, you can expect the back to run much hotter than the griddle as a rule. With secondary combustion taking place in the rear of the stove, surface temps on the back wall of my stove can easily exceed 800F if the stove is cranking with a full load of dry wood and strong draft conditions.

My stove sits in a fireplace, and I use a fan (blowing cooler floor air to the back of the stove) to both control the stove temp and to help circulate room air. Though I have not done so, I have considered putting in a flue damper, but I expect it would take some babysitting to ensure damper adjustments did not interfere with secondary combustion (killing the draft too much could kill the secondaries pretty quickly with my stove, as too little draft is just as problematic as too much draft).

 

[Kobeman]

I stayed up late reading on here about the everburn, I'd never heard it called that just a secondary combustor, but Yes it is. Should I put a probe thermometer in the pipe? I'm going to put a damper in tonight just so It's there, I got worried as the surface of the tile on my cement board wall shield was reading 130 deg my laser thermometer aimed behind it said around 85 or so, still learning what's hot and then What is too hot . I believe the flue temp will climb when the secondary gets going even if the griddle is stable, If so what are your normal flue gas temps?

 

[begreen]

130F is what our drywall reads behind the flue pipe. That is a safe temp. Usually it's considered safe for a combustibl wall to be up to 170. If you have a proper ventilated cement board wall shield you should be in good shape with no worries.

 

[branchburner]

What I did was get a second magnetic stove-top thermometer and put it on the back wall of the stove, where the secondary burn chamber generates the most heat. This serves two functions: it lets me know if it's too hot back there (short of the stove glowing, which has never happened to mine but has happened to others), but it also lets me know if the secondaries are active or have failed.

When getting a fire to the temps required to engage secondary combustion, my stove top can quickly push 700F while the back of the stove is around 200F. When I close the bypass, if the secondaries are firing up the stove top will drop to around 500F while the back of the stove quickly moves up to over 400F, potentially as high as 800F when cranking. Flue temps drop.

But if I close the bypass and the secondaries are NOT firing, even as the stove top drops to 500F the back of the stove remains around 200F. Flue temps do not drop as much. This tells me that my stove is not re-burning correctly because I do not have a coal bed that is deep/hot enough, or that I closed the primary air too far and/or too quickly, or that my wood is wet/unseasoned, or that my combustion package and/or stove pipe is clogged, or that the gods hate me, etc.

 

[Oldhippie]

I stayed up late reading on here about the everburn, I'd never heard it called that just a secondary combustor, but Yes it is. Should I put a probe thermometer in the pipe? I'm going to put a damper in tonight just so It's there, I got worried as the surface of the tile on my cement board wall shield was reading 130 deg my laser thermometer aimed behind it said around 85 or so, still learning what's hot and then What is too hot . I believe the flue temp will climb when the secondary gets going even if the griddle is stable, If so what are your normal flue gas temps?

Well, my memory isn't perfect.. but I KNOW that the flue temp is much lower than the griddle temp. Flue temp as read with a cheapy magnetic is under 500'F when griddle can be 700'F. (In fact it might be lower) But the runaway burn you talk about and the noise of air whistling through the stove has me concerned that the stove damper isn't sealing correctly and you are bypassing the combustor and creating overheated flue temps. Check that flue damper, is it closing solid and tight? This is the one controlled by the lever on the rear right of the stove as you are looking at it.

 

[Oldhippie]

Thos combustors are $200 bucks, but I'll bet yours is all deteriorated and about half the size it should be.. this opens up that air passage in the back, just like your not shutting down the damper.. path of least resistance to airflow.. and whoosh.. away you go.

I would definitely plan on replacing that combustor. I hate to say it, but I think you'll be taking that top off again to get at it easily enough, but sometimes you can take the fireback plates out and get at it that way, if they aren't warped.

Got pics??! We LOVE pics! Here's a pic of mine.

 

[Kobeman]

I will check the damper tonight, I'm sure its tight, I opened it back up during this event and a glow was coming from around the combustion package as looking through the damper while main fire box had no flame since I had the air shut down. Outside of my double wall was arround 220 or so. From what you guys have told me It appears perhaps it may have been running normally. I will install a keydamper tonight and check the damper seal and give it a go again, Armed with a key damper and my custom secondary air block off I'll feel more comfortable knowing I can pull the reins back harder on it if need be, thank all of you for your help with this!

 

[Kobeman]

I'll get you some pictures, The combustor was all intact, even the baffles were in it, It fit snug and the side plates and upper fit tight to it. I antisiezed it all knowing i'd porb be back in there soon. Seems its been 1 step forward 3 back this whole project but I hope to get the bugs worked out soon

 

[Kobeman]

thought about that some more Oldhippie, Now I understand what your saying that the secondary air coming in the REAR small non adjustible hole is bypassing the combustor box. and going up the flue. Should I be seeing anything out of the air holes in the combustion box? To me It looked like it was drawing up through them but it was hard to see, anyway I have one on oder.

 

[Oldhippie]

What I did was get a second magnetic stove-top thermometer and put it on the back wall of the stove, where the secondary burn chamber generates the most heat. This serves two functions: it lets me know if it's too hot back there (short of the stove glowing, which has never happened to mine but has happened to others), but it also lets me know if the secondaries are active or have failed.

When getting a fire to the temps required to engage secondary combustion, my stove top can quickly push 700F while the back of the stove is around 200F. When I close the bypass, if the secondaries are firing up the stove top will drop to around 500F while the back of the stove quickly moves up to over 400F, potentially as high as 800F when cranking. Flue temps drop.

But if I close the bypass and the secondaries are NOT firing, even as the stove top drops to 500F the back of the stove remains around 200F. Flue temps do not drop as much. This tells me that my stove is not re-burning correctly because I do not have a coal bed that is deep/hot enough, or that I closed the primary air too far and/or too quickly, or that my wood is wet/unseasoned, or that my combustion package and/or stove pipe is clogged, or that the gods hate me, etc

Branchburner, I am not sure if his an Everburn or not. I don't think mine is, a Resolute Acclaim Model 2490. ..no Everburn.. so that's what I'm describing.

I am not an aficionado of what they made when back 2 years ago.

 

[Oldhippie]

Well if the combustor is all in one piece than you're all set there.

Hmmm... as long as the bypass damper is closing than you ought to be good.

 

[Oldhippie]

Kobe, you may not need one if it looks physically okay.

The secondary air inlet (in the back) feeds the cumbustor so I I don't think you are bypassing air there.. I was worried about the primary bypass you use to get the stove started and then close when it gets to heat.

One thing I do now remember from previous years is that at night I get it up to temp.. then load it up to max at like 10:30PM and close it all the way down on the main air feed in front, and close the flue damper just to maximize the burn time. If I got up in the middle of the night I'd go refeed it, but otherwise a supercedar and some small splits in the morning like 5:30AM and it would come right back to life. This year I've got a Woodstock Fireview in the main living area, so I'll only use that Acclaim as a 2nd stove on super cold days to warm the family room a bit.

If you intend to keep the stove, and you've put enough work into it now that you probably will, then you'll need a new combustor someday.

I can't explain that high rush of air you're getting.. for me it was a completely deteriorated combustor.. so the air just blew through the afterburners in the back end of the stove.. but if you've got a solid combustor in there.. and it sounds like you do.. then you should be good. By the way those afterburner tubes in the back with the large heatsinks on the outside fill up with debris and will need a vacuum now and then. (Half way through the winter)

 

[Kobeman]

Oldhippie your talking about the channels on each side of the combustor behind the sealing plates right? Mine is a model 0041 thats been upgraded with the fire brick and new sides etc. I'm not exactly sure what an everburn is or how its different from this setup. I thing she was just drafting hard fro the wind and I got concerned it was getting too hot. Like I say when I covered up that small hole in the back she simmered right down. Everything I've read talks about stove top or flue temp and I wasn't expecting the back to run hotter tha the stove top. I kinda panicd when I discovered the back was hotter than the top I'd been watching. I plan to keep this stove awhile, wish id found this site before I bought it, doesn't seem like its popular round here!

 

[branchburner]

Branchburner, I am not sure if his an Everburn or not. I don't think mine is, a Resolute Acclaim Model 2490. ..no Everburn..

Not sure if they had an "official" name for it on that model, but I believe the burn technology is similar... just wanted to be clear that "combustor" in this stove referred to a rear-chamber, down-draft combustion package rather than a cat.

I have purchased a new one for my stove at about $250 -- I think the VC price is similar. I agree, a new package should not be required if it is in one undamaged piece and not clogged or overly degraded

A note on vacuuming... after a few season, the package becomes quite brittle and fragile (at least the Harman did, although they have upgraded it to a sturdier construction) -- if not careful when cleaning, it is very easy to vacuum pieces of the combustor right off and damage it.

 

[branchburner]

Mine is a model 0041 thats been upgraded with the fire brick and new sides etc. I'm not exactly sure what an everburn is or how its different from this setup.

Everburn was just a trade-name for that burn technology in some VC stoves... I probably shouldn't have bothered using the term, not really important (just confusing!).

I believe your part is the same as in the model 2490:
COMBUSTION PACKAGE (1602497)

 

[Oldhippie]

Oldhippie your talking about the channels on each side of the combustor behind the sealing plates right? Mine is a model 0041 thats been upgraded with the fire brick and new sides etc. I'm not exactly sure what an everburn is or how its different from this setup. I thing she was just drafting hard fro the wind and I got concerned it was getting too hot. Like I say when I covered up that small hole in the back she simmered right down. Everything I've read talks about stove top or flue temp and I wasn't expecting the back to run hotter tha the stove top. I kinda panicd when I discovered the back was hotter than the top I'd been watching. I plan to keep this stove awhile, wish id found this site before I bought it, doesn't seem like its popular round here!

yes, that's what I'm talking about.

They are pretty nice stoves once you get them running right, and once you learn how to manage you're particular installation.

The top loading is really convenient, and they are a pretty stove. They heat very well, but aren't all that good at going all night long on real cold nights. I usually was able to get mine restarted in the morning, ...but not if I slept late.

The downdraft design isn't as simple as most basic stoves and can frustrate people. I think you're stove is probably doing exactly what it should be doing.

Use it a while as it gets colder and you'll grow to like it. I would add that flue damper.. can't hurt, and is useful.

 

[Kobeman]

So, I instaled a key damper tonight. There is no wind however, checked out the stove and lit her up. I have my key damper wide open, total different stove from last night, it's crusin now at 550 stove top, 1/4 Air, back of the stove is 650-700. outside of doublewall pipe 190-200 no funny smells, controlable, nice. I will see how the damper helps out when the winds return. Here's a pic before I broke it in, sorry I didn't get an action shot tonight.

 

[Oldhippie]

Pretty stove and nice installation. How many square feet are you heating with it? If you can get it hot and then fill it tight before bedtime, and then close it down with the primary and key damper and if you've got good wood, you'll just have to open it up in the morning and feed it some small splits and off you go.

I bought a case of supercedars, I think it was 70 in a box, and I've still got more that half left from last year.. and throwing one of those in and then the splits and instant fire.

 

[Kobeman]

Thanks! Mostly just to heat the first floor, 1100 sq ft roughly. Its a smaller stove I know but the room its in , or any room, is not that big. If it gets terribly cold the furnace can help out I guess. I wanted a stove pretty bad and I like the looks of this one. I have warming shelves but since I had to change the top, they don't match so I'll have to get the Bordeaux ones some day. Been using super cedars to light, they are awesome! Burning some maple now as it's not that cold out yet.

 

[webbie]

Hmm......no "combustors" ever that I remember in the Resolute Acclaim. I owned and used one myself - probably the same model.
There is a combustion package in the rear - the soft ceramic which forms the secondary burn chamber.

Let's be clear. This is a non-catalytic stove.

As far as the temperatures reached, the Acclaim and other similar stoves tend to have VERY high stack temperatures as well as massive amounts of heat radiating off the flue collar area! There were many reports here of the flue collars glowing on some other "everburn" models. So these are very unlike most cat stoves.

I loved my stove - but feel that the designs had/has many shortcomings. As an example, having a stove which radiates much of it's heat off the rear and top rear is contrary to many installations. Fireplace mantel clearances on the thing were very high!

Also, the combustion is so good that it seems to generate too much heat which can't be reclaimed in the short heat exchanger - hence the high stack and flue collar temperatures.

Early versions of the Acclaim pretty much all fell apart. I know those are strong words, but we sold 100's of them and every one which was used in a real fashion (3+ cords a year) needed quite a bit of service or a complete tear-down and rebuild. Never models lined the sides and other parts with refractory instead of iron and probably last longer...

My Acclaim at home didn't fall completely apart because I only used 1 cord or so each year - because I was in the shop burning about 5 other stoves all day long.

Anyway, the main thing with these stoves is to try not to burn them at a very high blast....then they will last longer (and need less parts replacement).

 

[Kobeman]

Hello, Hate to bring this up again but I'm at wits end with this thing. Short Summary of work I've done to the stove recently: New combustion package, new gaskets again between back and fireback/side plates. I questioned my cement job from the rebuild so I knoced it apart, cleaned everything, and re-sealed it again. Problem is the back of the stove will on certain loads, not each one, get hot enough to glow, 850 measured with IR, at the point where the combustion package outlets are on the inside. When it does this the griddle will only be about 450. Flue temp will be 700-900. Most loads it will be 450 griddle to start, although this can reach 600 by end of the burn, 600 flue, 720ish on the back. running air at about 1/2, I get under 1/2 much and it back puffs. Thought I had a draft problem, measured with a Dwyer 460 air meter it says around .10 and if I close the key damper I installed it will read .06-.08 in h20. I question the accuracy of this meter. I've tried covering 1/4 of the seconday air slot with a magnet, this doesn't seem to affect it much, when the back gets around 850 I cover the whole slot to bring the back and the flu temps back down. I've ran it with the damper closed allthe way and it will burn good for a couple loads then next load it will struggle to stay going, this will conviently occur when I want to get to bed. It's hard to set the air on this thing when the griddle never gets hot. , I usualy get it up to 400 flue then close damper, let it ride 10 min or so till fire is goin well then ack air off in steps till about 1/2 which apers to be the sweet spot without back puffing. If I give it more air the flue gasses just come up, not griddle. SO. can someone tell me what draft I should be looking for? Why does the griddle not get hot? Thoughts on why the back gets so hot? If I cant get this stove to where I can trust it I'm about ready to cut my losses and cut it up for scrap. I put hours into this thing and wat to make it go but the lack of sleep babysitting it, and the frustration are taking its toll. I appreciate any advice you may have, thanks!

 

[branchburner]

"Why does the griddle not get hot? Thoughts on why the back gets so hot?"

This is the nature of downdraft stoves. With the secondary combustion taking place in the rear chamber, that's where the heat is. Both the Lopi Leyden and several VC models seem more prone to glowing in the back than my Oakwood, but I have seen mine push 800F easily if I don't shut back the air and/or turn on the fan..

The good news is that you have an outlet right next to your hearth pad. As mentioned above in the thread, I would suggest setting up a small fan -- probably just off the hearth pad, against the wall by the outlet -- that blows cool floor air towards the back of the stove. This should not only keep the back a bit cooler, it should help circulate warm air through the room and house.

I am not sure why you are getting backpuffing with air at less than half -- it I kept my air halfway open or more, throughout a full load, I would be burning too hot, as it sounds you are. After the back of the stove starts heating up, I bring the air back, in steps, to anywhere from 1/8 to 1/3 for the burn. Are you shutting back the air gradually? I burn at 3/4 when I first close the bypass, then 5-10 minutes at 1/2, and only then do I close it back more. If I go go straight from 3/4 to 1/4 or less, I will sometimes get backpuffing. Try experimenting a bit.