I'm going to second what NunYaBusiness said - you are
most likely being too aggressive in turning down the air after engaging the cat AND your wood is
probably a little wetter than your moisture meter indicates. CAT stoves are more finicky than tube stoves on startups with slightly not well-dried wood, but will burn it fine once they have a chance to drive off that extra moisture (my own experience).
Personally, I don't think the inexpensive moisture meters are all that accurate and I'd prefer using an ohmmeter and a lookup table because it can vary a lot by wood species. I also think the inexpensive moisture meters are calibrated for softwoods commonly used for framing lumber and given erroneous readings for hardwood (it is also tougher to get their prongs deep enough into hardwoods to get an accurate reading). This is a great thread to read and well worth your time:
https://www.hearth.com/talk/threads/using-a-multimeter-to-measure-wood-moisture-level.40033/
I know you are focusing on the stove being bad, or the catalytic combustor being bad, but the reality is that these are the two least likely things going wrong. Most likely is that your wood is not as dry as you think and maybe second most likely (but not all that likely) is some type of blockage in your chimney. 95% probability is that your wood is sub-optimal and has more moisture than you think. I know you don't want to hear that, but that is the simple lived reality for most of us hearth.com members here when a new member starts visiting the site and describing how their stove isn't working very well (I myself was a new member who did this very thing).
Yes. This is my third year burning with my Woodstock cat stove but the first year burning with wood that has been cut, split, stacked, and covered for three years. This year's wood has bark falling off and is a mix of sugar maple, black walnut, and I have a little bit of hickory. The difference in how the stove performs with this year's wood is dramatic compared to last year or the first year (with more marginal wood). In fact, what you are describing sounds like my first two years of burning with a CAT stove.
Even this year, sometimes I shut down a little too early and the CAT stalls and I have to open the door and get is some air and get some flames going and then shut the door and close the bypass to engage the CAT and start the process again. Sometimes it's three starts. Sometimes there is just a piece of wood that starts hissing as soon as it is in the stove and I know this is going to be a more difficult startup.
I wouldn't try to follow all of Woodstock's recommendations too religiously about temperatures and times and what not when starting a new fire - you to have to figure out what works for your setup and this year's wood supply. Also (maybe I'm reading too much between the lines) but it sounds like you might be in a rush in the morning trying to get the stove to settle in before you dash off to work - that can be frustrating with marginal wood, for sure.
OK, assuming that you are willing to consider that your wood might be a little less than well-dried for burning in a CAT stove, try reloading with smaller splits (1" or so across) on the bottom or some small softer wood splits (i.e. not ash or oak) on the bottom. Then, keep the loading door open for a few minutes (
closely monitor this so you don't get an aggressive fire in the firebox), then close the loading door but don't shut the bypass (or engage the CAT). Do flames die out? If so, wood is wet and you may have to repeat the process. If flames continue, let it go for 5 minutes (set a timer) and then engage the CAT but keep it at full air. Do flames die out? If so, wood is wet and you may have to start the process again with the open loading door (open bypass/disengage CAT first). Yeah, it might take a few iterations with wet wood. (I know you are likely going to tell me your wood is not wet, but in three years you'll be telling us how much better your stove burns with better dried wood - trust me).
Then, once the CAT is combusting, close the air in 25% increments (or faster if it is really taking off and there are too many active flames in the firebox). Give it about 5 minutes between adjustments. I start with my air fully open, and when the cat is glowing a bit, I'll shut it to 3 or 2.5 (depending) and then a few minutes later to 2 (or 1) and then all the way down to 0 on the coldest days (I have good draft from a tall chimney). I never go from engaging the CAT to setting air to 1 (25% open) at the same time.
Also, sometimes the CAT starts to work and it just takes time to "glow". I've learned to be patient and just let it go at its pace. Of course, I work from home and I'm not trying to dash off to work, so I don't need to rush the burn cycle. Oak, for sure, is going to take longer to get going compared to dried ash or maple or softer hardwoods.
Yeah - you repeated this a bunch. You are going to have to experiment a bit with your setup and your wood supply. Try not to be too locked into a process during startup. If the stove works great once it's running, then there is nothing wrong with the cat and most likely your wood has more moisture in it than you think. I've learned over the years that I don't need a moisture meter anymore - if the bark has fallen off the splits, then the wood is ready to go, and that takes three years after cutting, splitting, and stacking (covered).
