2022/23 VC Owner thread

[Catesy]

This is kinda bad.. you probably should go with a catalyst.. Whata the MC of your wood.. have you checked.. just Curious

Catalyst is on back order. MC is 15-20.

 

[Lorde]

Assuming 6 inch liner..

Correct 6". I attached a picture of the thermocouple hole. Also the casting around the holes to the cat chamber aren't great but I'm probably being picky. Overall pretty happy, inspector coming Friday then off we go.

 

[Woodsplitter67]

Correct 6". I attached a picture of the thermocouple hole. Also the casting around the holes to the cat chamber aren't great but I'm probably being picky. Overall pretty happy, inspector coming Friday then off we go.

View attachment 307991 View attachment 307992 View attachment 307993

The probe area doesn't look bad..

Your set up looks good.. whats your wood situation like

 

[Lorde]

The probe area doesn't look bad..

Your set up looks good.. whats your wood situation like

Not great. I had 2 chords of split "seasoned" wood delivered early September. Has been stacked and covered since. I have not tested since delivery but it is a mix of species and moisture content, worst was some oak at like 25% . Everything but the oak was right around 20% back then.

I also just cut down 10 mature standing dead hemlock. I did not split any yet to test but standing dead for 2+ years.

 

[JohnDaileyNH]

Cleaned the stove out tonight and it went nuts. Fighting the cat going insane. Loaded it cat at 700 and it immediately went up to 1500. Just constant now trying to keep it from overheating. Just when it seemed to be running real smooth

 

[arnermd]

Just out of curiosity whats your woods MC

My good stuff is 12-15%. I have two metal roofed sheds where I store 4 cord each for 2 years. All red oak and ash.

The last 2 weeks I have been burning some junkier stuff, stored on pallets under tarps for one year. MC is 15-20%, it sat in my neighbors yard on ground for 2-3 years, so it is lighter than the "good stuff". Definitely gives me shorter and cooler burns, I have to leave the air open longer to get the cat temps up.

Can't imagine 5% MC.... that's really low.....

I can see why your drafting super hard.. 8 inch pipe 23ft high is a monster vacuum machine..

We thought about doing a 6" liner but figured bigger is better, and manual recommends 6 or 8". Knowing what I know now I would probably go with 6....

The results of my damper experiment are somewhat perplexing....

• Stove is definitely running different than before, cat temps are a bit less aggressive. And I do get some smoke out of the griddle during a reload, never did before.
• Draft measurements
  • Not a big change in readings, I really need to data record draft throughout the burn to get a better feel for how it changes. Thinking about how to do that now.....
  • Draft readings before were 0.08 - 0.13 iwc depending on stack temp, bypass closed, key damper open, 100% air.
    • "Nominal" readings were .1 - .12 iwc
  • Draft readings after damper mod are now 0.06 - 0.13 depending on stack temp, bypass closed, key damper open, 100% air.
    • Nominal readings are ~0.08 iwc
  • The nice thing about the damper mod is if the cat runs off on me I can close it down and reduce the draft to almost nothing and bring cat temps down... eventually. The old damper seemed to have no effect when closed.

Long answer to a simple question.... I need to work on shorter posts.... opportunity for improvement.

 

[arnermd]

Correct 6". I attached a picture of the thermocouple hole. Also the casting around the holes to the cat chamber aren't great but I'm probably being picky. Overall pretty happy, inspector coming Friday then off we go.

Probe insertion looks fine to me as well. I would not be concerned with that one bit.

Interesting that your 3 secondary feeder holes in the second pic seem to be biased towards the center. Pretty sure mine are evenly spaced. Wonder if they made a design change.... or maybe I am just misremembering mine....

Also.... Standing dead will be wet, not as wet as green but still needs a year to dry.... In my experience. I dropped a dead oak 3-4 months ago, split it right away, tried to burn it recently and it did not burn very well. MC was 20-25%..

 

[arnermd]

Cleaned the stove out tonight and it went nuts. Fighting the cat going insane. Loaded it cat at 700 and it immediately went up to 1500. Just constant now trying to keep it from overheating. Just when it seemed to be running real smooth

hahahahaha (evil laugh)..... you got my demon, call a priest. 👹

Initial thoughts:

• Sounds like a possible wood placement issue, try to keep your back bottom piece away from the smoke inlet. When i load I always put the back one in first and set it 2-3 inches in front of the smoke inlet. Then I place the next one in front of it against the andirons.
• Stove runs better (calmer) with a bed of ash / coals on top of the grate. Some people say a full ashpan helps too.... I have not found a difference there.
• 700 is a little on the hot side for a reload, I think. I am sure @Woodsplitter67 does it with success. I tend to wait for cat temps to drop to near 600..... with mixed results....
• I personally do not "clean" my stove, if the ash bed is really thick I will knock it down to the ash tray. If the ash tray is near full I empty it. I clean the glass once in a while. Every 2-3 weeks I will check on the cat and f there is a lot of ash buildup under the cat I will vacuum it (maybe 1-2 times per season). I "clean" my stove in May.....

So you reloaded with cat at 700.... does that mean it was the second load after cleaning? Did you light off a smaller load from cold let it coal up and then reload?

 

[JohnDaileyNH]

So you reloaded with cat at 700.... does that mean it was the second load after cleaning? Did you light off a smaller load from cold let it coal up and then reload?

First reload after cleaning the ash out. I had my startup fire from cold. Had a bed of coals. Loaded. And to the moon it went. Damper cycled open and closed for an hour and finally I just smothered it with a couple scoops of the ash I had just shoveled out of the stove

 

[NewGuy132]

First month with the Dauntless Flexburn without the cat. I've been burning wood for many years, never seen it this bad in such a short time. Guess I need to run a little hotter. Going to do another sweep this weekend.

View attachment 307982

Yea that doesn't look good. Looks like mine last year after a couple months burning 30% wood with a CAT. I had a chimney fire last year when it was this caked up. This year I'm on a monthly sweeping schedule and I am burning much better wood.

 

[vernorz]

Looking for a more seasoned opinion on the condition of my chimney. This is after about half a cord, no cat. Thoughts?

 

[arnermd]

Looking for a more seasoned opinion on the condition of my chimney. This is after about half a cord, no cat. Thoughts?

Looks great to me..... 1/2 cord is not a lot though..... Color is interesting, more gray than black. I think that's a good sign.

I usually get dry, jet black crumbles, like @Woodsplitter67 pics above.

 

[arnermd]

First reload after cleaning the ash out. I had my startup fire from cold. Had a bed of coals. Loaded. And to the moon it went. Damper cycled open and closed for an hour and finally I just smothered it with a couple scoops of the ash I had just shoveled out of the stove

Wondering if the temps were rising from the initial burn when you reloaded.... maybe the "momentum" of the first burn carried the cat temps. If so maybe wait a bit longer next time for cat temps to start falling before reloading?

My current thinking is that these stoves are like riding a missile with no guidance system.... The initial trajectory of the burn sets the tone and direction for the entire load. I feel like there is very little we can do to change the course and you don't really know where it is going till you get there...

Wood placement might help.

Another thought.... maybe if you had a ripping coal bed, rake the coals a little towards the front and to slow things down and then pile wood in.

When I had events like this it seemed like the secondary was just sucking active flames right up off the bottom. You want to make it harder for the stove to do that.

 

[gthomas785]

My personal opinion is that a cat frame would not pop the refractory, the frames are too flimsy especially when hot. I think the frame would just deflect.

Okay, the 13" long one I purchased was a Condar CC-800.
Just a napkin calculation, but a foot long piece of SS will expand by about 3/16" when heated to 1400 degrees. So if you have less clearance than that it will still push against the sides, even if it's flimsy, and due to the shape of these refractory I don't think they can deform much in any direction without breaking something somewhere... Not trying to argue just sharing my thought process

 

[JohnDaileyNH]

Wondering if the temps were rising from the initial burn when you reloaded.... maybe the "momentum" of the first burn carried the cat temps. If so maybe wait a bit longer next time for cat temps to start falling before reloading?

My current thinking is that these stoves are like riding a missile with no guidance system.... The initial trajectory of the burn sets the tone and direction for the entire load. I feel like there is very little we can do to change the course and you don't really know where it is going till you get there...

Wood placement might help.

Another thought.... maybe if you had a ripping coal bed, rake the coals a little towards the front and to slow things down and then pile wood in.

When I had events like this it seemed like the secondary was just sucking active flames right up off the bottom. You want to make it harder for the stove to do that.

I think all of these probably would have worked better. Should have waited longer. Knew right away when it just started climbing fast. Every mistake is a learning experience this season. So we get better and move forward

 

[arnermd]

Okay, the 13" long one I purchased was a Condar CC-800.

That's very surprising to me....I have used 3 CC-800's over the years and none of them were a tight fit. Wondering if the one you got was out of spec....

Just a napkin calculation, but a foot long piece of SS will expand by about 3/16" when heated to 1400 degrees. So if you have less clearance than that it will still push against the sides, even if it's flimsy, and due to the shape of these refractory I don't think they can deform much in any direction without breaking something somewhere... Not trying to argue just sharing my thought process

I love the discussion, no hard feelings here. Challenging our theories makes them better, or demonstrates them to be false

• I do not disagree with thermal expansion logic (I did not verify your calc but I believe it). Certainly steel will grow more than refractory, and it will apply a force to the refractory if there is not adequate clearance when hot.
• My suspicion is that a thin strip of steel 13" long will tend to buckle before it can apply enough force to crack the refractory. Certainly the rolled edges of the frame member will increase the bending stiffness but I doubt it is enough.
• Also I just looked up yield strength for 304 SS and found this. At temps we are running (1400F = 760C) the steel is getting pretty flimsy.... Just to get a feel for it I looked up max yield stress for other materials at room temp. The closest I could find to 75 MPa was pure copper at about 70 MPa. So 304SS at 1400F has about the same yield stress as pure copper at room temp.
• My logic is it would be pretty hard to transmit a significant force with a thin sheet of pure copper without it buckling in the center.

• But at the end of the day, I do absolutely agree with your original statement.... you want some clearance for thermal growth.

I need to go find some pics of my old cats..... I was shocked at how much the metal frame moved and warped. Especially on the lower back corner becuase there is no refractory supporting the frame there...... All them are warped 0.5 - .75" in the center, towards the back of the stove.

 

[JohnDaileyNH]

That's very surprising to me....I have used 3 CC-800's over the years and none of them were a tight fit. Wondering if the one you got was out of spec....

I love the discussion, no hard feelings here. Challenging our theories makes them better, or demonstrates them to be false

• I do not disagree with thermal expansion logic (I did not verify your calc but I believe it). Certainly steel will grow more than refractory, and it will apply a force to the refractory if there is not adequate clearance when hot.
• My suspicion is that a thin strip of steel 13" long will tend to buckle before it can apply enough force to crack the refractory. Certainly the rolled edges of the frame member will increase the bending stiffness but I doubt it is enough.
• Also I just looked up yield strength for 304 SS and found this. At temps we are running (1400F = 760C) the steel is getting pretty flimsy.... Just to get a feel for it I looked up max yield stress for other materials at room temp. The closest I could find to 75 MPa was pure copper at about 70 MPa. So 304SS at 1400F has about the same yield stress as pure copper at room temp.
• My logic is it would be pretty hard to transmit a significant force with a thin sheet of pure copper without it buckling in the center.

View attachment 308023

• But at the end of the day, I do absolutely agree with your original statement.... you want some clearance for thermal growth.

I need to go find some pics of my old cats..... I was shocked at how much the metal frame moved and warped. Especially on the lower back corner becuase there is no refractory supporting the frame there...... All them are warped 0.5 - .75" in the center, towards the back of the stove.

I find it somewhat odd that the cat is as much of an issue and so sensitive on these stoves. This seems like an engineering problem that has existed for years and VC has repeatedly neglected to address this.

 

[arnermd]

Was just looking through some of my old posts, links to stuff below that may be of interest:

My first refractory failure is here, with pics. Look at the picture of the "refractory engine", that is extreme spalling.....
https://www.hearth.com/talk/threads/vc-defiant-2n1-cat-overtemp.164727/post-2209397

Posted in 2016 so that was ~5 seasons since new... roughly 20 cord.

 

[arnermd]

I find it somewhat odd that the cat is as much of an issue and so sensitive on these stoves. This seems like an engineering problem that has existed for years and VC has repeatedly neglected to address this.

In my opinion: the lack of secondary air control is a major design flaw..... Not that it cant work ever, under the right set of conditions it works fine.... deviate from those conditions and all bets are off. I am sure some will disagree and that's OK, just my opinion after years of running my stove.

That being said I do recognize that designing a wood stove in todays world is very challenging. Between the EPA mandates, ignorant users, highly variable fuel sources and draft conditions..... I do have some empathy for the technical challenge.

I would dearly love to know why VC abandoned the secondary bimetal air flow control..... seems like a great idea to me. Although many folks here have reported issues even with the secondary air flapper. Was it a cost reduction? Or was there some performance reason? or maybe they were driven to it by emissions standards.... IDK.

 

[Lorde]

In my opinion: the lack of secondary air control is a major design flaw..... Not that it cant work ever, under the right set of conditions it works fine.... deviate from those conditions and all bets are off. I am sure some will disagree and that's OK, just my opinion after years of running my stove.

That being said I do recognize that designing a wood stove in todays world is very challenging. Between the EPA mandates, ignorant users, highly variable fuel sources and draft conditions..... I do have some empathy for the technical challenge.

I would dearly love to know why VC abandoned the secondary bimetal air flow control..... seems like a great idea to me. Although many folks here have reported issues even with the secondary air flapper. Was it a cost reduction? Or was there some performance reason? or maybe they were driven to it by emissions standards.... IDK.

Maybe I misunderstood while researching my stove (Encore 2040 Cat C) but the brochure data still mentioned bi-metal control of secondary air. Is that not the case? Secondary air is just fixed?

 

[arnermd]

Maybe I misunderstood while researching my stove (Encore 2040 Cat C) but the brochure data still mentioned bi-metal control of secondary air. Is that not the case? Secondary air is just fixed?

I am not intimately familiar with the 2040 cat C but looking at the manual online it appears to me you do not have secondary air control. There is a bimetal thermostat that adjusts the primary air, same as my Defiant.

 

[arnermd]

Old pics....

My second failed refractory.... broke in two places, heavy spalling

2 Cats ago.... sorry terrible pic....
- Crumbled ceramic
- Severe frame warpage. That corner at the base of the red arrow is the lower back corner.

 

[JohnDaileyNH]

Old pics....

My second failed refractory.... broke in two places, heavy spalling
View attachment 308024

2 Cats ago.... sorry terrible pic....
- Crumbled ceramic
- Severe frame warpage. That corner at the base of the red arrow is the lower back corner.

View attachment 308025View attachment 308026

Would occasionally rotating the cat help with this or worsen the issue?

 

[arnermd]

Would occasionally rotating the cat help with this or worsen the issue?

hahaha.... I had the same thought.... the problem is once the frame blows out that bad you cant flip it and get the covers back on. That corner has to be the lower back corner, forevermore.

What I have been doing since is either wrapping the frame with SS safety wire in 3 places along the length or this time I took a steel band and wrapped it in the center and then folded the ends over each other. I should have done it in more places than just the center.... the current has blown out in between the ends and the center band, but not as bad.

 

[JohnDaileyNH]

hahaha.... I had the same thought.... the problem is once the frame blows out that bad you cant flip it and get the covers back on. That corner has to be the lower back corner, forevermore.

What I have been doing since is either wrapping the frame with SS safety wire in 3 places along the length or this time I took a steel band and wrapped it in the center and then folded the ends over each other. I should have done it in more places than just the center.... the current has blown out in between the ends and the center band, but not as bad.

well ideally we would be rotating it before it got to that point. Say every couple weeks or even weekly if the stove goes cold. But if every edge warped it may just crumble. Who knows, I am liking the idea more of the steel cat. But what will stop that from warping too?