Encore 2040 cat C burns too fast

[hoosierhermit]

My stove is a lot older than yours, but it is the original design of what you have. I can burn my stove with the damper open and easily control the fire and get overnight burns and never engage the cat. I burned like that for quite a few years with no problems other than cleaning my chimney more often. point is the firebox should be completely controllable with the primary air flap. If your stove can't do that I'd look a lot harder at the stove not sealing and sucking combustion air from somewhere.

I've checked everywhere I can think to and I've had a guy with 40 years of experience with wood stoves check as well and a source of air entry hasn't been found. I'm losing hope for a solution. If the stove is fine then perhaps the installation/pipe combination are responsible for too strong a draft? But, as i mentioned in the original post, I had a key damper installed in the pipe. I have no idea whether that should solve "too strong a draft" when it's completely closed, and therefore maximally reducing air flow, which is the position I have it in when burning.

 

[stoveliker]

I wrapped some gasket rope where the stove and first section of pipe meet to "seal" any potential openings where air could be entering and increasing the draft. It didn't make any difference in how vigorously the wood in the stove burned so I don't think that is the problem. It was a good idea though

Air leaking into the pipe will hurt draft, not increase it.

 

[arnermd]

Forgive me if someone already mentioned this....
Have you checked the gasket on the bypass damper? If that is leaking you could get a lot of air through the stove bypassing the cat and accelerating the primary burn rate (when the damper is closed obviously). Do you see a change in flame intensity when you close the damper? The flames should calm down fairly quickly after closing the bypass damper, in a minute or two.

More ideas:

• With some bar magnets or tinfoil, completely block the primary inlet and / or the secondary inlet and see if that kills the fire. With those sealed up the fire should be really smoldery, no flames at all. I would not do this for very long and I would do it with a small fire......
  • If the fire is still raging you definitely have an air leak somewhere, somehow....
• With regards to the key damper, I measure the pressure in my stove pipe right above the stove top so I know precisely how much it is affecting the draft.
  • My first damper had holes in it that would reduce the open area a lot but not completely shut off. I found closing this damper did not change the pressure at all when the stove was hot and I saw little/no change in the flame intensity.
  • My second damper was solid (no holes) and I found it made a small change in pressure when closed and flame did respond a little. It had some leakage around the circumference of the plate but not a lot. I was shocked at how little effect it had.
  • My last mod was to rivet a shelf inside the stove pipe on either side of the damper to give the plate a step to seat on. See my earlier post from 2023 I think.... This really kills the draft and I can actually quench the fire with it closed. Flames will go out completely in a few minutes. Be very careful if you do this, very high likelihood you will get smoke in the house with a well sealed damper. I use mine very sparingly for only the most extreme runaway incidents and I never leave sight of the stove when it is closed.
  • It was shocking to me how little open area was required to sustain enough airflow for a fire. I think my stove would run fine with a 1" dia hole, or even less on a typical winter day. Warm days would not work very well I expect....

 

[bholler]

Then you have massive air leak somewhere else.

Or the stove is massively overdrafting

 

[bholler]

I wrapped some gasket rope where the stove and first section of pipe meet to "seal" any potential openings where air could be entering and increasing the draft. It didn't make any difference in how vigorously the wood in the stove burned so I don't think that is the problem. It was a good idea though

How tall is your chimney?

 

[Turbo89]

Subscribing for a similar experience on a 2040 CAT C… although mine issues could be lack of experience with running a CAT stove.

 

[Woodsplitter67]

I didn't reat through the entire thread, I would do the following. Id start a cold stove and build a fire. Id get it going a little bit and just turn the primary air all the way back to see if you have control of the fire.. the flames should die down immediately. If you have control of the fire Id let the stove and pipe get up to temperature then do the same thing.. not closings the damper.. just turn the primary air back and see if the flames die back.. If the flames dont die back on the first one you definitely have a leak in the stove. if it does the stove itself is probably ok.. if the flames don't die back on the second one your draft is probably high.. Report back and Ill walk you through the next step..

 

[Turbo89]

I didn't reat through the entire thread, I would do the following. Id start a cold stove and build a fire. Id get it going a little bit and just turn the primary air all the way back to see if you have control of the fire.. the flames should die down immediately. If you have control of the fire Id let the stove and pipe get up to temperature then do the same thing.. not closings the damper.. just turn the primary air back and see if the flames die back.. If the flames dont die back on the first one you definitely have a leak in the stove. if it does the stove itself is probably ok.. if the flames don't die back on the second one your draft is probably high.. Report back and Ill walk you through the next step..

So here’s a small fire, about 20-30 min in.

CAT bypasses, primary air control all the way open.

And then about 6-8 min later, cat bypassed still and primary air all the way down (some control, but not smoldering). STT tell at 600 with it turned all the way down.

I tried the dollar bill trick for draft, I can feel a small draft near the front right of the griddle (pulls dollar bill in when it’s within 1/4” or so), and on the left portion of the front of the ask tray (opposite the locking handle), about the same pull/distance. Ash tray was emptied before the fire.

Here’s the air control full open (where
You can see secondary air intake) and fully closed (I can’t pull it closed anymore, so it seems to be fully closing).

 

[Turbo89]

And about 20 min later with the car engaged (crept up to about 60” deg). Note I added 2 bolts to the secondary cat intake based on some post here, trying to get more control.

Air fully on/open, CAT engaged:

About 5 min after turning air fully closed, still some dancing flames, cat temp crept up at 40 degrees, now is coming down.

 

[Woodsplitter67]

There is a big difference between flames on the actual wood and secondary combustion inside the firebox. I can completely extinguish the flames on the wood for a period time. I will still get secondary combustion in the firebox. The combustion will be directly over the wood or I get rolling flames right at the primary airwash by the top if the glass. Very rarely during a burn will I not have secondary combustion at some point. So there is a big difference between the two and if your confusing the 2 this may be part of the issue.

 

[Turbo89]

There is a big difference between flames on the actual wood and secondary combustion inside the firebox. I can completely extinguish the flames on the wood for a period time. I will still get secondary combustion in the firebox. The combustion will be directly over the wood or I get rolling flames right at the primary airwash by the top if the glass. Very rarely during a burn will I not have secondary combustion at some point. So there is a big difference between the two and if your confusing the 2 this may be part of the issue.

I’ve yet to see rolling flames, not on the wood., but I know it must be burning the smoke, because my CAT seems up run at 1000-1200 deg with a half load, and it went nuclear last night (almost 1700) when I stuffed it full.

Any thoughts on why I’m having short burns/nuclear CAT temps with a full load or does anything look odd in the above pics? Maybe ash tray / top griddle gaskets?

 

[Woodsplitter67]

Its hard to tell by the pictures as the glass is kinda dirty.. Follow the above post and do that test with a cold stove. build a fire let it burn 10 minutes and cut the air with damper open.. let the stove get up to temperature and do the same thing..

 

[Turbo89]

Its hard to tell by the pictures as the glass is kinda dirty.. Follow the above post and do that test with a cold stove. build a fire let it burn 10 minutes and cut the air with damper open.. let the stove get up to temperature and do the same thing..

That what’s post #33 was, cold stove. note that the glass got dirty from that test.

Perhaps interestingly, I’m down checking on it now and about 3hrs later that one of two small logs hasn’t completely burned, so maybe it just likes to run not full.

I’ll try the clamped paper gasket test in a few days when it cools off. Trying it now the top lid / vent draw are clamping tight.

Had anyone tried blocking part of the secondary air on the back side? It looks like a partial block plate could be easily attached with that one screw above it…

 

[skb31]

I run mine with 2 or 3 of the 8 secondary intake holes blocked with #10 screws. I used hex head ones so I had more surface area to remove them. Normally 2 but the cold and wind last week, I added a third because the draft was strong. My stove is in the basement and the chimney is a longer run. I had a key damper installed before this season but haven’t needed it.

My primary air works just as woodsplitter described above in an updraft fire. It has a strong effect on the flames. My issues last season were with the bypass damper engaged. I would be all the way air closed with temps rising towards 1600 in the cat chamber.

I can successfully run my stove without the catalyst per the instructions I was given. Temps north of 1200 are possible without the cat. I have learned how to run it successfully with the catalyst but the installer, my chimney guy, and my paper instructions all say it’s fine to run it without.

To answer your question, I made an emergency plate attached with ferrite magnets for the secondary air intake last season before I found what works for my setup. It does work but a key damper is easier to use. I think @arnermd has a plate he used as well.

That air intake is unregulated and I was corrected somewhere on this forum about it recently. If that information is correct (and it makes sense to me), the 8 air intake holes on the bottom wall allow air to pass into the firebox but a significant amount of the secondary air flows directly into the cat chamber.

Hot reloads are done with big splits for me. Gaining more control of the primary air by limiting the secondary air a bit is a big part but the size of the splits on reloads were game changing for me. The bigger the better.

 

[Turbo89]

I run mine with 2 or 3 of the 8 secondary intake holes blocked with #10 screws. I used hex head ones so I had more surface area to remove them. Normally 2 but the cold and wind last week, I added a third because the draft was strong. My stove is in the basement and the chimney is a longer run. I had a key damper installed before this season but haven’t needed it.

My primary air works just as woodsplitter described above in an updraft fire. It has a strong effect on the flames. My issues last season were with the bypass damper engaged. I would be all the way air closed with temps rising towards 1600 in the cat chamber.

I can successfully run my stove without the catalyst per the instructions I was given. Temps north of 1200 are possible without the cat. I have learned how to run it successfully with the catalyst but the installer, my chimney guy, and my paper instructions all say it’s fine to run it without.

To answer your question, I made an emergency plate attached with ferrite magnets for the secondary air intake last season before I found what works for my setup. It does work but a key damper is easier to use. I think @arnermd has a plate he used as well.

That air intake is unregulated and I was corrected somewhere on this forum about it recently. If that information is correct (and it makes sense to me), the 8 air intake holes on the bottom wall allow air to pass into the firebox but a significant amount of the secondary air flows directly into the cat chamber.

Hot reloads are done with big splits for me. Gaining more control of the primary air by limiting the secondary air a bit is a big part but the size of the splits on reloads were game changing for me. The bigger the better.

Thank you! It must have been your post I was referring to above, I added two socket head screws to plug the larger secondary bypass screws this morning.

I’m running another test load now, I filled it with 2 medium logs and a few small pieces about 1.5hrs ago and will check it in 3-4 more hours to see how it’s burning. On that reload I engaged the CAT and slowly turned the air down until the CAT stabilized around 1,000deg. I noticed this time that I was able to reduce the CAT temp with the primary air control, which is a welcome change from last night when it went nuclear and wouldn’t respond (I pulled wood out).

Do you ever fill your stove up to the bypass, almost to the brim? I’m used to my older Jotul stove, where I literally pack it full, ignite, then turn the air way down…. So far this Encore doesn’t seem to like that approach.

 

[skb31]

I don’t ever load it to the height of the bypass damper and always keep it below that level. I push the coals against the back wall into a nice level pile then carefully load two splits up against the back wall and a third between the bottom piece and andirons at most. If I’m going to be hanging around the stove I’ll load only two splits a lot of the time as I don’t mind tending to it. Loading it this way keeps my STT under control as well allowing me to run it off the cat chamber probe temps.

Many small splits are what is going to spike the cat temps in my experience. They all seem to catch and off gas at the same time.