vermont castings intrepid flexburn trouble controlling burn

[jstol]

I'm late to the party here but I have a Intrepid flexburn with about 2 years experience running it. I have the same issues with the glass getting dirty quickly. jstol I see your post where you vacuumed two small holes in the burn plate that took care of this issue. What burn plate are you referring too? When I bought the Intrepid was told by dealer right off not to expect the glass to stay clean. Maybe this is my problem as well??? The Damper gasket is a bear to replace correctly. The track needs to be perfectly clean and the damper closed on it to hold it in place till the gasket cement can dry. Otherwise the damper would need to be removed to facilitate cleaning and gasket replacement. Fun stuff. I attribute the dirty glass issue to the design of the airflow within the stove.

its called a refractory burn plate. if you have your manual it has a list of parts with pictures so you can locate where it is. If not its just the stone? non metal back plate of the firebox. those holes when stuffed with ash, I believe, slow the sir to the secondary burn chamber and would slow the burn of my stove, it didnt really have much of an effect on the glass. Do you have control of the temperature of the air handler with the damper closed? I believe the root of my problem is with the damper gasket. when closed air is getting in and renders the secondary air handler moot. this results in a hot fire and clean glass. I don't feel comfortable loading it up at night though if I cannot control the rate of burn. I think the dirty glass in general is as you say, poor airflow and design.

 

[Kevin Weis]

Okay, your talking about the secondary burn holes in the refractory combustion chamber. There are I believe 5 holes there. Theoretically plugging any of those holes would increase the airflow through the glass wash and therefore keep the glass cleaner. However you would be comprising the secondary burn system and creating more smoke and creosote in the flue. I have some control with the primary air intake lever. An investigation into this I made last year and found that moving the air control lever from one extreme to the other only netted about 3/16" open/close in the air intake flap at the bottom. So therefore your not going to be able to make. However the chain that connects the lever to the intake flap is adjustable to make shorter or longer to adjust the amount of primary air intake. Longer = less air and shorter = more air. You have to take the rear shield off to access that. So now comes the crazy part. There is also a second chain from that lever to a second air intake flap the opens and closes alternately with the primary air intake. When the primary is fully open the secondary intake flap is closed. Conversely when the primary is closed down it opens this secondary intake flap. I've been told that this is safety feature to prevent a draft stall in the flue during low burns. None of this secondary air intake is mentioned or shown in the manual or even so much in the parts diagram. This action between the primary and secondary air intakes I believe greatly dilutes the responsiveness of the primary air intake lever. Also this secondary intake bypasses the stove box and combustion chamber all together and goes strait to the flue exit at the top of the stove which indirectly would pull more air through the stove. Agin to prevent a draft stall. I think this is a goofy design to say the least. In theory if you disconnect this secondary air (unhooked the chain) the primary should be more responsive. I don't nessasaraly advocate doing that but what I've done is make that secondary air independently controlled by a separate turn knob. This probably a topic for another thread.

 

[Kevin Weis]

And as if I haven't said enough, this air intake lever is intrical with a bi-metal thermostat which I think compromises the responsiveness of air intake changes via the primary lever. The thermostat sets out from the stove some so any change in temp from the firebox to the thermostat has a significant delay.

 

[jstol]

Okay, your talking about the secondary burn holes in the refractory combustion chamber. There are I believe 5 holes there. Theoretically plugging any of those holes would increase the airflow through the glass wash and therefore keep the glass cleaner. However you would be comprising the secondary burn system and creating more smoke and creosote in the flue. I have some control with the primary air intake lever. An investigation into this I made last year and found that moving the air control lever from one extreme to the other only netted about 3/16" open/close in the air intake flap at the bottom. So therefore your not going to be able to make. However the chain that connects the lever to the intake flap is adjustable to make shorter or longer to adjust the amount of primary air intake. Longer = less air and shorter = more air. You have to take the rear shield off to access that. So now comes the crazy part. There is also a second chain from that lever to a second air intake flap the opens and closes alternately with the primary air intake. When the primary is fully open the secondary intake flap is closed. Conversely when the primary is closed down it opens this secondary intake flap. I've been told that this is safety feature to prevent a draft stall in the flue during low burns. None of this secondary air intake is mentioned or shown in the manual or even so much in the parts diagram. This action between the primary and secondary air intakes I believe greatly dilutes the responsiveness of the primary air intake lever. Also this secondary intake bypasses the stove box and combustion chamber all together and goes strait to the flue exit at the top of the stove which indirectly would pull more air through the stove. Agin to prevent a draft stall. I think this is a goofy design to say the least. In theory if you disconnect this secondary air (unhooked the chain) the primary should be more responsive. I don't nessasaraly advocate doing that but what I've done is make that secondary air independently controlled by a separate turn knob. This probably a topic for another thread.

holy cow! you know way more about this than i do. My goal is to just have some control over the flame. sounds like you have dissected your stove. pretty cool. I let my stove cool overnight and checked the gaskets. all good. I did notice the cap to my clean out tee was about to fall off so I secured it and put a set screw in to hold it more permanently. whistle is a lot less and I have gained some control over the flame. I may look into adjusting the chains on the secondary air control but if I don't have to I don't know if I want to get that far into it. given the variability in this stoves performance though never say never. thanks for the info.