OK,I'll throw out some stuff, from things I remember, perhaps before I forget,lol.
Harman is terrible about releasing information. We the people sometimes will never know about changes.They want you to use a dealer,always,it seems, and even then, it seems a lot of the technical bulletins and stuff never make it to the tech's themselves, owners just stuff them in a file.
So,as said, yes newer boards will work, they are adjustable. Some older boards would only use the black exhaust probe, new boards can use either.
The feeder units are basically all the same. Fire pots are different.
Yes the combustion blower does change speeds, most people just never notice. BUT they might not on the corn stoves,I am not sure.
I have never figured out, nor has Harman explained the differences in the Accentra, Accentra2 and the Accentra Cast,lol! Mine is a 06, so a "2", but has the old style feeder,BUT has a single bold/wingnut in the center of the fines cover, that holds the fines cover on, which was for older models, and the furnaces.
Anyway, there are 2,so far, feeder units, early and late. Most, if not all, "chain drives",(like mine) are early, BUT perhaps there were early P68's with direct drive? Someone knows, and doesn't intrest me enough to research.
Over the years, Harman "upgrades" things, to fix problems that have popped up in stoves after being out for a while. Probably the most well known was changes in some burn pot designs, especially the 52i. BUT they never release the info for WHY
Augers were changed, but probably to reduce a part number- the slot in the front for stoves with stirrers.
Control boards updated. My experiences have been, the newer the control board, slightly less heat, but, a much cleaner burning stove. Probably done so newer units met emission standards.
I feel combustion motors have gotten cheaper, but don't have the problem of the old ones, which was slow starting if they are cold.
Some Accentra installs had poor draft. There was a high altitude impeller, they also came out with a reducer ring, that goes onto the impeller cover, basically speeding up air flow, you might want to try this, if you have always felt your stove should be burning cleaner, BUT, a replacement impeller cover now comes with a smaller opening. Again, they don't say why, but pretty sure we figured this out.
Not so long ago, the chain drives were "upgraded", the replacement set has 2 sprockets the same size, instead of a large and small one. Currently, the old style parts are still available, but being phased out. Again, no information as to why,lol.
Chain drive motors are now solidly mounted to the bracket. This was probably done because of the motor/chain moving around, causing snaps,pops and other strange stuff. You can buy the expensive bracket, or you can just remove the rubbers, and space with some washers.
Clean and lube your chain. I never see this recommended, but it makes motor work easier, quieter, and sprockets last longer.
OK, If I got anything wrong, please correct me, my memory has never been fantastic.
