Intrepid II cat too hot, had trouble getting the temp down

[gthomas785]

Not sure. I know typical combustion requires fuel and air. But a cat is partly a chemical reaction to the gasses the wood produces when it smolders. When you cut air to the burning fire you create more smoke/gasses. Im sure air is required for the cat process but I would guess less is required then for normal combustion?

Well the starting and ending materials are the same (smoke + O2) -> (CO2 +H2O) but the cat enables the reaction to happen at a lower temperature.

So yes I probably choked the fire too fast and created a puff of smoke that made the cat temperature shoot up. But then shouldn't it gradually calm down after that, even with excess air? I'm just thinking out loud here

 

[hansenjw]

On a cold stove the secondary probe should be somewhere around the 2 o'clock resting position. This is where the rod is connected to coil. There is a nut and set screw holding it all together. Loosen the nut and change the resting position to your desired setting. Make small increments in your testing and good luck. I have spent hours tinkering with it trying to get it perfect. Never could that’s why I decided to just disconnect the rod and leave it shut. I have started thinking about somehow making the shutter a manual control with some sort of lever attached to it. This way I can choose to open or shut it without having to reach behind a hot stove to make any adjustments. However, every time I start tinkering around I always end up just leaving it fully shut.

Last night I had another runaway cat. Not too bad, only hit 1600 before I intervened. However, I took a look at the secondary air flap, and it was raised! The thermostat had wrapped all the way around and was bringing it back up. So yeah, it sounds like I need to try this adjustment. I’ll probably give it one shot and if that doesn’t work I’ll just disable the thing.

 

[RandyBoBandy]

Last night I had another runaway cat. Not too bad, only hit 1600 before I intervened. However, I took a look at the secondary air flap, and it was raised! The thermostat had wrapped all the way around and was bringing it back up. So yeah, it sounds like I need to try this adjustment. I’ll probably give it one shot and if that doesn’t work I’ll just disable the thing.

Very frustrating I know. On a cold stove check the timing. You may have to move it back some or just give up and disable it like a few of us have already.

 

[RandyBoBandy]

Can anyone fill me in on what VC is doing with the secondary air on newer models?

 

[gthomas785]

Here's a pic of the secondary air mod I'm trying out. Took a piece of 22ga galvanized and drilled some holes in it, and bolted it on. Seems to work well. I might need to add a couple holes because now the cat tops out at 1000 and smokes a little. (Ignore the burn marks, that's from some foil tape I had on there before).

 

[gthomas785]

Can anyone fill me in on what VC is doing with the secondary air on newer models?

I haven't torn my Encore apart but I believe it is just a fixed air intake slot.

 

[Diabel]

The thermostatic probe on the old encores was a bust for sure

 

[gthomas785]

Can anyone fill me in on what VC is doing with the secondary air on newer models?

Here's the secondary intake slot on my Encore (2020 model). No variable flap that I can see, but I can't get too close cause the stove is hot right now. I've never had a runaway cat with this stove, highest cat temp I've ever seen is 1500.

 

[Diabel]

Here's the secondary intake slot on my Encore (2020 model). No variable flap that I can see, but I can't get too close cause the stove is hot right now. I've never had a runaway cat with this stove, highest cat temp I've ever seen is 1500.
View attachment 271004

Is this an upside down pic? I would think

 

[gthomas785]

Is this an upside down pic? I would think

That's looking up from the floor at the back of the stove. You can see the primary intake (with the grill cover) at the bottom, and just above it is the secondary intake with some of the refractory cement visible through the slot.
The slot is in a horizontal piece at the bottom of the combustion chamber.

 

[gthomas785]

Maybe this would help with the orientation

 

[hansenjw]

Here's a pic of the secondary air mod I'm trying out. Took a piece of 22ga galvanized and drilled some holes in it, and bolted it on. Seems to work well. I might need to add a couple holes because now the cat tops out at 1000 and smokes a little. (Ignore the burn marks, that's from some foil tape I had on there before).View attachment 271001

This is gold! I love your technique of drilling holes to find the right amount of air, although I suppose you could just swivel the plate to expose a bit at the bottom. Maybe that might give more air to one side of the cat vs the other?

I think someone else said something about using aluminum duct tape to cover most of the slot. I like the idea of being able to adjust it though, to find the point where it maxes out at exactly 1500.

What size drill bit did you use, in case I copy you?

 

[gthomas785]

I think I used a 3/16 bit, honestly didn't pay attention just grabbed one from my drill case. Your optimum setup is probably going to vary based on draft etc.

Edit: it was 1/8"

I tried the foil tape first, but I found that once the stove got going the adhesive melted and the tape peeled off leaving that black gunky mess. I also messed around with a piece of aluminum flashing but found that it was too flexible and wouldn't sit flat so I couldn't get a good seal.

Whatever you end up doing just pay attention to the cat performance and fine tune it a little at a time. I have not gotten mine perfect yet but the stove feels much more controllable and doesn't give me heart palpitations like it used to.

 

[WoodBurnerInWI]

Last year was the first year with my stove (which for was my first time with a catalytic stove) and I remember for half that winter my cat would peak at 1,500 to 1,600 before going back down. I thought I was loading too much wood in the stove, I didn't realize at the time it was literally just something that a new catalyst does. This year is much better as it tops out around 1,200 and stays there for awhile before going down.

 

[RandyBoBandy]

Here's the secondary intake slot on my Encore (2020 model). No variable flap that I can see, but I can't get too close cause the stove is hot right now. I've never had a runaway cat with this stove, highest cat temp I've ever seen is 1500.
View attachment 271004

Thanks for the pics.