VC Defiant only runs only at full throttle.

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Comeaud

New Member
Dec 8, 2021
2
Massachusetts
Good evening!

This is the first time that I have ever had to post an issue about a wood stove.

I have a VC Defiant catalytic stove. It was bought new at the beginning of 2020. This stove replaced a VC Encore. I have owned wood stoves in other houses and never experienced an issue or behavior like this.

For context the installation is very straight forward. The chimney is a 8” lined pipe that goes straight through the ceiling. Total length is 20’ from the stove. (We started with 16’ but added an additional 4’ while attempting to solve the issue.) The stove is installed in an open hearth made of stone. The installation was performed by a local pro whom I have been using for years prior to this stove.

The house itself is not super tight and on most occasions I have a window near the stove cracked to ensure air flow.

When I light the stove it works as it should. The air shutter keeps good control of the burn and the draft is strong. When the reburn damper is closed the stove continues to function normally but continues to get hot, hotter than desired. I try to keep the griddle temperature between 500 and 600. When I close the shutter with the damper closed the fire stalls and I immediately get a large back puff out of the stove and smoke comes out. The fire relights, goes out, back puffs, and repeats. If you open the throttle back up it rights itself but continues to get hotter than desired and tares through fuel.

The other odd issue is when it’s about to back puff you never see any issues with the draft pulling up through the catalyst, it’s like the issue is originating in the fire box.

Myself and the guy that installed and serviced the stove have checked everything on the stove, regasketed it, made adjustments, sealed all of the joints on the chimney, measured the draft in several occasions, and ensured that the wood was at the proper moisture level. Nothing has helped or even reduced the occurrence of this issue.

I’m hoping someone might have an idea or two. I know burning wood is an art rather than a science and that no one setup is the same as another but I’m at a loss and about ready to close the stove down and use it as a table.

Thanks for your time!
 
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Reactions: Earlnemo

Rickb

Minister of Fire
Oct 24, 2012
1,213
St.Louis
So... A lot going on here.

First.
When you close the bypass(I assume this is what you are calling a damper) you are then forcing your exhaust through the cat. Cats burn off smoke by running very high temps. So I would expect to see the temps rise a lot once you close the bypass.

Second.
If your fire is stalling when you close the air down and the stove is hot, you either don't have enough draft, your wood is wet, or your stove is broke. 80% of the time on this site the wood is wet. 18% the draft is bad. 1.5% its some weird other issue. And 0.5% a stove issue.

Can you post pictures of your setup and chimney? Have you tested your wood?
When you turn your air control down does the flames get lazy or go out?
If you don't turn it down as much does it not get so lazy?
 

Comeaud

New Member
Dec 8, 2021
2
Massachusetts
Hey Rick. Definitely a lot going on and it’s frustrating the hell out of me.

When the bypass is closed I would definitely expect to see an increase in flue temperature which I do. With it closed it’s about 450 to 500 degrees. This is where the current stove and every other stove I have had likes to be once the bypass is closed. The temperature that goes up higher than I want is the griddle temperature. I try to run it around 500 to 600 but with the damper closed and the shutter needing to stay wide open the griddle can get up to 700 or higher. This being the case I don’t feel safe leaving it alone and I certainly can’t throw an “all nighter” piece in the stove. I have to babysit it constantly so it doesn’t run away and let it go out before we close up the house and go to bed.

Regarding the draft, I believe that I was pulling about .06 inches of water column which should be ideal for this setup with the length and size of my flue. We have tried a few “draft enhancers” as well. I have not gone as far as installing a fan on the chimney with a pressure switch and I honestly feel like this would be an unnecessary and costly expense.

The wood is dry and stored indoors. The moisture content is 17%. No bacon and eggs sound when it’s burned! I have taken wood from a friends house as a test and had the same results.

As soon as the shutter is starting to close the fire goes out and the cycle listed above starts. I’ve never been able to get this stove to slow down to a mild, clean and lazy burn. It slows down a bit when the damper is closed but again the shutter being open keeps it moving.

Also, I have reached out to the shop where I bought the stove from. They have been less than cooperative and boarder line hostile when I suggested that the stove is defective and needed to be replaced. VC has also been less than helpful and they keep directing me back to the dealer.

The guy that did the installation and that has been helping with this refuses to charge me for his services because nothing has worked. He is more baffled by this than I am. He’s extremely reputable and experienced. He told me recently “I’m sure this is a very tired cliché but in 25 years I’ve never seen a stove behave like this.”

I will get some pictures tomorrow for you once the sun comes up.
 

moresnow

Minister of Fire
Jan 13, 2015
2,083
Iowa
Good evening!

This is the first time that I have ever had to post an issue about a wood stove.

I have a VC Defiant catalytic stove. It was bought new at the beginning of 2020. This stove replaced a VC Encore. I have owned wood stoves in other houses and never experienced an issue or behavior like this.

For context the installation is very straight forward. The chimney is a 8” lined pipe that goes straight through the ceiling. Total length is 20’ from the stove. (We started with 16’ but added an additional 4’ while attempting to solve the issue.) The stove is installed in an open hearth made of stone. The installation was performed by a local pro whom I have been using for years prior to this stove.

The house itself is not super tight and on most occasions I have a window near the stove cracked to ensure air flow.

When I light the stove it works as it should. The air shutter keeps good control of the burn and the draft is strong. When the reburn damper is closed the stove continues to function normally but continues to get hot, hotter than desired. I try to keep the griddle temperature between 500 and 600. When I close the shutter with the damper closed the fire stalls and I immediately get a large back puff out of the stove and smoke comes out. The fire relights, goes out, back puffs, and repeats. If you open the throttle back up it rights itself but continues to get hotter than desired and tares through fuel.

The other odd issue is when it’s about to back puff you never see any issues with the draft pulling up through the catalyst, it’s like the issue is originating in the fire box.

Myself and the guy that installed and serviced the stove have checked everything on the stove, regasketed it, made adjustments, sealed all of the joints on the chimney, measured the draft in several occasions, and ensured that the wood was at the proper moisture level. Nothing has helped or even reduced the occurrence of this issue.

I’m hoping someone might have an idea or two. I know burning wood is an art rather than a science and that no one setup is the same as another but I’m at a loss and about ready to close the stove down and use it as a table.

Thanks for your time!
This topic would likely be better addressed in the VC thread. I believe. Good luck and welcome to Hearth.

@begreen
 

Earlnemo

New Member
Nov 19, 2020
16
knox county, tn
Hey Rick. Definitely a lot going on and it’s frustrating the hell out of me.

When the bypass is closed I would definitely expect to see an increase in flue temperature which I do. With it closed it’s about 450 to 500 degrees. This is where the current stove and every other stove I have had likes to be once the bypass is closed. The temperature that goes up higher than I want is the griddle temperature. I try to run it around 500 to 600 but with the damper closed and the shutter needing to stay wide open the griddle can get up to 700 or higher. This being the case I don’t feel safe leaving it alone and I certainly can’t throw an “all nighter” piece in the stove. I have to babysit it constantly so it doesn’t run away and let it go out before we close up the house and go to bed.

Regarding the draft, I believe that I was pulling about .06 inches of water column which should be ideal for this setup with the length and size of my flue. We have tried a few “draft enhancers” as well. I have not gone as far as installing a fan on the chimney with a pressure switch and I honestly feel like this would be an unnecessary and costly expense.

The wood is dry and stored indoors. The moisture content is 17%. No bacon and eggs sound when it’s burned! I have taken wood from a friends house as a test and had the same results.

As soon as the shutter is starting to close the fire goes out and the cycle listed above starts. I’ve never been able to get this stove to slow down to a mild, clean and lazy burn. It slows down a bit when the damper is closed but again the shutter being open keeps it moving.

Also, I have reached out to the shop where I bought the stove from. They have been less than cooperative and boarder line hostile when I suggested that the stove is defective and needed to be replaced. VC has also been less than helpful and they keep directing me back to the dealer.

The guy that did the installation and that has been helping with this refuses to charge me for his services because nothing has worked. He is more baffled by this than I am. He’s extremely reputable and experienced. He told me recently “I’m sure this is a very tired cliché but in 25 years I’ve never seen a stove behave like this.”

I will get some pictures tomorrow for you once the sun comes up.
This topic would likely be better addressed in the VC thread. I believe. Good luck and welcome to Hearth.

@begreen
Did this thread get moved, or just die? I have a 2020 Intrepid , similar issue recently.

Additional clue with mine: there is an adjustable elbow attached to the cast iron stove collar (run horizontal, hearth install), the other end attaches to the liner. When I get the little puffs in the stove box, I can see a little smoke exiting here (as well as from the griddle) , so there is a bit of leakage? 16-18% Hickory.

24' of 6" insulated ss inside an external brick chimney (inside the old 8" clay tile, actually). Also, I do not have the cat package in mine. The dealer didn't have one when I bought and I haven't gotten around to it yet.
 
Last edited:

Caw

Minister of Fire
May 26, 2020
1,336
Massachusetts
Good evening!

This is the first time that I have ever had to post an issue about a wood stove.

I have a VC Defiant catalytic stove. It was bought new at the beginning of 2020. This stove replaced a VC Encore. I have owned wood stoves in other houses and never experienced an issue or behavior like this.

For context the installation is very straight forward. The chimney is a 8” lined pipe that goes straight through the ceiling. Total length is 20’ from the stove. (We started with 16’ but added an additional 4’ while attempting to solve the issue.) The stove is installed in an open hearth made of stone. The installation was performed by a local pro whom I have been using for years prior to this stove.

The house itself is not super tight and on most occasions I have a window near the stove cracked to ensure air flow.

When I light the stove it works as it should. The air shutter keeps good control of the burn and the draft is strong. When the reburn damper is closed the stove continues to function normally but continues to get hot, hotter than desired. I try to keep the griddle temperature between 500 and 600. When I close the shutter with the damper closed the fire stalls and I immediately get a large back puff out of the stove and smoke comes out. The fire relights, goes out, back puffs, and repeats. If you open the throttle back up it rights itself but continues to get hotter than desired and tares through fuel.

The other odd issue is when it’s about to back puff you never see any issues with the draft pulling up through the catalyst, it’s like the issue is originating in the fire box.

Myself and the guy that installed and serviced the stove have checked everything on the stove, regasketed it, made adjustments, sealed all of the joints on the chimney, measured the draft in several occasions, and ensured that the wood was at the proper moisture level. Nothing has helped or even reduced the occurrence of this issue.

I’m hoping someone might have an idea or two. I know burning wood is an art rather than a science and that no one setup is the same as another but I’m at a loss and about ready to close the stove down and use it as a table.

Thanks for your time!

Not sure if I'm missing something but are you trying to run this stove on an 8" flue? It's never going to work on 8"... it simply doesn't generate enough gas. You're going to have terrible draft. I didn't see any mention of a 6" liner inside the chimney.
 

RandyBoBandy

Minister of Fire
Feb 25, 2015
1,355
Whitmore lake, MI
Did this thread get moved, or just die? I have a 2020 Intrepid , similar issue recently.

Additional clue with mine: there is an adjustable elbow attached to the cast iron stove collar (run horizontal, hearth install), the other end attaches to the liner. When I get the little puffs in the stove box, I can see a little smoke exiting here (as well as from the griddle) , so there is a bit of leakage? 16-18% Hickory.

24' of 6" insulated ss inside an external brick chimney (inside the old 8" clay tile, actually). Also, I do not have the cat package in mine. The dealer didn't have one when I bought and I haven't gotten around to it yet.
The smoke has to go somewhere when you get a back puff. They are basically mini explosions. So the pressure is pushing smoke out of anything it can. There probably isn’t a leak at the griddle it’s just being pushed up some by the back puff.