I also had trouble keeping my PH from going into secondary burn mode really quickly, before I got a chance to engage cat. Woodstock suggested either getting a damper installed in the stovepipe or trying to engage cat by loading the stove with hot ash in the bed, closing everything down immediately, and waiting. I did the latter, and it worked. After 1/2 hr to 45 min got a cat burn going. Once my wood is down to moderate amount of coals, I rake coals to front ,open damper gradually (first 1/4, the 1/2 then full) to burn coals hotter/more quickly down to ash. Had no smoke smell during any of this.
Twice in the early stages of owning the stove, starting top down fires with knotted newspaper, I got an incinerating whoosh as I closed the loading door, with very significant shaking of the stove pipe (2nd time worse than first), so no longer start top down fires with newspaper--use white birch bark.
Three weeks or so into burning with the PH, started to smell smoke. Over the next two days stove noticably became harder to get into cat mode, then just stopped going into cat at all, was not burning well at all..window, which had been crystal clear, became smudged. So cooled the stove, checked iconal screen, completely blocked. Took it out and cleaned it. Opened top, cat looked fine, from Fireview experience expected it to be fine. I was shocked..entire distal surface completely covered with very fine gray ash. Gently knocked cat upside down on newspaper, brushed all sides with natural bristle sash brush, replaced, brushed, vacuumed inside of top of stove (ash and soot there) put everything back together, cleaned ash out of firebox, and loaded stove about 75% full---of 16 " wood,---lit fire, bypass open, damper fully open. Fire lit very quickly, gradually reduced damper to 1/4. After ten flue temp as measured on outside of excel double wall pipe about a foot above stovetop, which I have found to have readings consistently 1/2 of stovetop temp whenever stove is in a steady burn, was 130 -150 (I don't now recall exactly where in that range), closed the bypass to engage cat, then reduced damper to about 1/8 for a few minutes, then completely closed it. Got a 16 hour cat burn with plenty of coals (1/2 gallon to 1 gallon, again don't remember exactly) but mostly white-gray ash. No smoke smell. Since then have found this method works for me in my setting. Stove cruises along at about 380-420 degrees. To get it hotter, I open the damper a bit. If it is really cold out and I open the damper a bit more again I get a hot secondary burn. But as long as I keep the stove from going into secondary burn at the beginning, which I do by engaging according to flue temp, I don't have a problem with secondaries taking over when I don't want them to do so. On a reload stove is frequently still up ~ 300, and the flue ~ 150. The wood ignites immediately...before the door is closed often...and I have trouble making myself wait the ten minutes I should before closing the damper all the way and engaging cat...I do start shutting the damper immediately in this setting, to 1/2 then on down to 1/4, 1/8 engage cat, close completely. The fire usually dies pretty quickly and the cat takes over with cat flames just like in the Fireview, but a bit more spectacular. Sometimes stove goes completely black but as long as stovetop temp rises I don't worry. Occasionally if I am too anxious to engage cat, and close the bypass too soon, it doesn't seem to engage, but if I open damper to 1/8 for just a few minutes, it engages. Then I close the damper completely. Almost always burn (this winter) with the damper closed, unless it is raining. By raking coals toward end of burn I get pretty consistent 12 hour cat burns, which is more convenient for me than 16 hour burns, which are easy to achieve by NOT raking the coals and letting the stove cool down to about 225-250.
I haven't had a smoke smell since cleaning the stove. I'm sure mine was the result of clogged system resulting in poor burn and smouldering. I have a theory that whooshes suctioned fly ash up into the working parts of the stove & blocked everything. I definitely notice that with my draft ,if I have the damper open much, fly ash is lifted up and flies around in my firebox. So far, a few of the squares in my iconal screen have fly ash covering them, but most are fine and I have not had further problems with burning or smoke smell. Trying to avoid situations which make the ash fly. Seem to burn at cooler temperatures than lots of people which may make a difference in the amount the cat expands and contracts and may result is less problem with leakage of smoke around the cat. (That was not an issue with ceramic cat.) Keep a fire going 24/7 except when away for an extended period. I heard somewhere that getting the cats cold and starting them again repeatedly is hard on the SS cats. Don't know if that is so, but with this mild winter I wonder if some people light a fire once a day and let the thing go out with the PH because PH heats the house so well. If any one does that, what has your experience been with the cat?
In summary, if I go by flue temp not exceeding 150 on excel double wall pipe as guide to engage cat from a cold start,and about ten minutes burn time with slightly charred wood as a guide to engage cat in a hot stove, I engage cat successfully within ten minutes and achieve a long cat burn with damper completely closed. Really mild out (28F or higher) and wet out, then I may need to open damper 1/8 inch for this burn. To achieve hotter burn than 380-420, again, open the damper about 1/8". To move to hot stove box on a really cold day I open the damper a bit more and get the secondaries going.
