Intrepid flexburn smoked glass why?

[Kevin Weis]

Sorry for the long winded thread on this but trying to figure out why the glass smokes so bad on this stove when it seems to function okay otherwise. The manuals are no help with this. This seems to be a common issue with these stoves but why? The stove as an air wash system for the glass. Why is it not working? My thoughts are as follows:

1) The air wash flow is compromised by having the primary air volume split between the combuster and the air wash so already 50% less going to the air wash than what's going into the stove firstly.

2) The air hitting the glass doesn't get sufficiently warmed up cooling the glass and thus promoting the soot/creosote formation on same.

3) Insufficient draft to the stove. Installation manual says minimum of 0.03 inches H20 to operate properly. That's not much draft.

4) MC of wood too high?

5) Stove not hot enough

6) All of the above?

I'm using wood with a MC of <16%. Think my draft is sufficient but getting a manometer to check that. Run STT around 400 cat temp 1000 doesn't clean glass off. Still not hot enough? Glass temp with IR gun is around 500. I have an OAK attached to stove but maybe that's cooling the primary air too much? Maybe air wash ducts partially blocked? Don't see how thats possible but I guess is a possibility. May remove those airwash manifolds in the near future to check. Any other thoughts or if someone as gotten the stove to keep the glass relatively clean I'm all ears. Thanks.

 

[stoveliker]

The cat temp is not relevant. It is the firebox condition that matters. The cat cleans up smoke after it exits the box.

A cat stove that runs at lower output can essentially smolder, smoke up the window. A half hour fire on high (e.g. after reloading) should clean it up.

Was the mc measured on a fresh surface after resplitting the split?

 

[Kevin Weis]

Yes, I measured my firewood MC a few months ago. Fresh split at 65f air temp, all <16%. Some actually around 11%. Readings taken on the face of the split.

 

[stoveliker]

Draft measurement is good, but 0.03 is not a high demand.

My (cat, not hybrid) stove gets dirty window too when burning low. If one burns so low that there is no flame but the wood smolders, the firebox including the window will get dirty.


Have you done a dollar bill test to see.if the door gasket is still sealing well?

Can you move.the window in the frame (two flat hands on each side. Be careful not to lift the door off its hinges, if possible)?

 

[Kevin Weis]

No leaks in the door gaskets. Glass is seated well on the gaskets with the clips. I've never had the STT higher than about 450 or so. Was always thinking that's hot but actually it's considered medium heat. Still convinced it's the engineering of the airflow in the stove whereby by design there insufficient air directed to the airwash to keep the smoke away from the glass. They have a goodly part of it directed to the combustion chamber. Other thought was possible clog in the air manifolds which actually are not gasketed.

 

[stoveliker]

Yes, it is the air flow. But that can get exacerbated by the issues noted before. That may not be the case here.
Regardless, when I burn "low", my window blackens too. It's the nature of the beast: if one burns at low output, temps are low, and not all stuff combusts. Hence smoldering/smoke. That will get onto walls and windows in the firebox. Note that when you burn at low output, the airflow is low too. Hence the airwashing is not optimal.
Especially if exacerbated by issues. So it's important to rule those out. Hence the questions.

Last question I have is what the chimney set up is. How tall, what (single/double wall) inside, elbows, how much outside, etc.

Maybe all is well, and it's the nature of the beast here. I hope someone owning this stove will chime in.

 

[Kevin Weis]

Masonry outside 23' or so above stove top. First 6' of the chimney are 1 foot thick. Clay thimble goes through this part. 8" clay flue has 6" stainless steel liner minimally insulated. Thimble is 2' above stove top. Lateral run all-in-all between stove outlet and chimney flue (center to center) is about 32"-34". I can move the stove closer to the vertical flue by about 4" and still meet setback requirements which I'll do this spring anyways. That will give me a little more draft I would think. The stove pipe to the thimble is single wall 45 degrees from stove top to thimble. I did order a manometer to measure the draft to see what I got before I do anything too drastic here. Draft specs for the Intrepid are 0.03 - 0.065. The installation manual says if draft is outside of these parameters stove will not operate as intended.

 

[GrumpyDad]

Sorry for the long winded thread on this but trying to figure out why the glass smokes so bad on this stove when it seems to function okay otherwise. The manuals are no help with this. This seems to be a common issue with these stoves but why? The stove as an air wash system for the glass. Why is it not working? My thoughts are as follows:

1) The air wash flow is compromised by having the primary air volume split between the combuster and the air wash so already 50% less going to the air wash than what's going into the stove firstly.

2) The air hitting the glass doesn't get sufficiently warmed up cooling the glass and thus promoting the soot/creosote formation on same.

3) Insufficient draft to the stove. Installation manual says minimum of 0.03 inches H20 to operate properly. That's not much draft.

4) MC of wood too high?

5) Stove not hot enough

6) All of the above?

I'm using wood with a MC of <16%. Think my draft is sufficient but getting a manometer to check that. Run STT around 400 cat temp 1000 doesn't clean glass off. Still not hot enough? Glass temp with IR gun is around 500. I have an OAK attached to stove but maybe that's cooling the primary air too much? Maybe air wash ducts partially blocked? Don't see how thats possible but I guess is a possibility. May remove those airwash manifolds in the near future to check. Any other thoughts or if someone as gotten the stove to keep the glass relatively clean I'm all ears. Thanks.

Im very very down on VC right now. I own the dauntless and have the same issue and so much more that we just dont use our stove anymore. It's a piece of useless furniture.
That said, all of the items you mentioned will help this flawed appliance be more flawed. You have to create such perfect conditions for this stove to avoid the glass turning black. As many people will likely point out, using the cat may help as that seems to be the broad spectrum antibiotic statement to solve all problems for these stoves. Im just not buying it though however @Jmorg has had a better experience going from non cat to cat with both heat control and how the glass appears.

 

[Jmorg]

Im very very down on VC right now. I own the dauntless and have the same issue and so much more that we just dont use our stove anymore. It's a piece of useless furniture.
That said, all of the items you mentioned will help this flawed appliance be more flawed. You have to create such perfect conditions for this stove to avoid the glass turning black. As many people will likely point out, using the cat may help as that seems to be the broad spectrum antibiotic statement to solve all problems for these stoves. Im just not buying it though however @Jmorg has had a better experience going from non cat to cat with both heat control and how the glass appears.

It's been better, but definitely not perfect. Personally, I think the airwash system is not the best...had minimal dirty glass with my old tube burner. With all of the problems that you have had, you might just have a lemon unfortunately. Maybe something is wrong with the internals of your stove and possibly covered under warranty.