This is true in a older type stove, but at least with my catalyst EPA stove (not sure of the air tube type EPA stoves) it works most efficiently when damped down. The reason is that once you have a hot fire and get the Cats like 500F i think you can close the bypass door to let the smoke go through the Cat. This will cause it to light off and start reburning the smoke, causing the temps of the cat to rise into the 1000F range i beleive. It will glow red in there when working well and you will have no visible smoke coming out of the chimney (mabe a few wisps every now and then, but just heat lines). Damping it down to cause a tiny flame or just smoldering produces smoke while letting enough air to still allow full combustion of the wood, all while the Cat is burining the smoke off at super high temps to produce heat for 6-12 hours depending on wood type, size and quantity loaded.
I wrote the following at the start of the thread, but wanted to see if anyone answered the question. Here is what I wrote.
I'm from the South, and I've studied this really hard, but I just don't know everything yet. But here is my opinion:
Creosote buildup has a great deal to do with moisture content, and burning rate. If the moisture is high, it will burn slow, and smolder. If the moisture is low (wood is dry) it will burn well, and hot. So, if you do not stifle the fire by depriving air, you will get your catalyst hot plenty fast, and you can then use the catalyst to keep the flue clean, and get the heat out of the load of wood.
I think what I told you is correct. But, I'd tend to trust my manual on the stove, and if I didn't agree, I'd call the manufacturer and ask to be sure. A man wants to protect his catalyst.
Now I add this..I have the epa non catalyst. It is similar in how we both must operate our stove. You bypass, and get the heat up quickly so your catalyst will fire. I do the same, but having no bypass, I am trying to get the ceramic above my heat tubes hot, so the secondary air coming through the air tubes will burn the smoke. After you and I accomplish that, and we are burning the smoke, you can turn your air way down. I can too, but not as far as you.
You can only put significant heat into your FLUE for creosote prevention in bypass, and that defeats the goal of your stove.
I can not put significant heat into my flue in any case, since I have no bypass, and the rather tortuous path the exhaust takes gets most of the heat out anyway. So, you and I both rely on burning our smoke in our stove. Dry wood and good technique will do that.
To be on the safe side, my flue is well insulated top to bottom, and properly sized. It is hoped that the insulation will keep the flue as hot as it can be, but if I do have a creosote fire, the stainless, and the insulation around it, will protect my lined rock chimney. I still clean it once a year.
Also, look down your flue before you burn the pine. Heck, take a picture. Burn it two weeks, then snap another. Proof is in the pudding. You could resolve all fears with a before / after flue and catalyst inspection.
You almost never see any smoke. I almost never see any smoke. So long as that is true, we are not putting creosote in our flue. You must additionally not foul your catalyst. Hopefully, DRY wood is putting burnable smoke into your catalyst. Wet wood will produce steam, and take the catalyst temperature down out of the sweet spot, foul the catalyst, and soot your flue.
