The only thing I can think off as far as the heat exchanger is that baffle at the top of the fire box the one with all the holes in it. i know some people have played around with removing it and the result seem to be all the heat going up the flue. you didn't do anything with that? like maybe remove it to clean it and not put it back? Not having your exact model I'm assuming you have that baffle its held on by about 4 screws.
also I would try what luke said and reset all the c-codes back to factory and see what happens.

Gonna try this. Think and know there is soot on baffle yhat I cant get. Goin to remove to clean and do a leaf vac outside on exhaust tube. I think the soot ontop of baffle is insulating and not letting exchanger do its job and heat goin out exhaust.

Reset codes, no difference. Tried another vacuum pressure switch, no difference

Haven't done circuit board switch yet cause not here. I did full clean of unit using leaf vac on outside of exhaust tube. Pulled baffle off and noticed tons of ash hoping this could be part of the issue. I've done everything other than circuit board so it has to be it. U1 is 315 and u2 is 88. I'm stumped.


Baffle is back on, I have never removed it. Pulled off to clean and reinstalled

315/88 thats seems like a lot better.
you are cleaning behind the two slide doors on each side of the burn pot aren't you? you can get a lot of ash build up in there also.
keep us posted

Yes I have, this was a full clean. I always clean behind the small doors.