OK all - I think it's time to have the dealer come out and check it. Seems like consensus is something is awry, I am going to buy another thermometer today as a double-check, but bottom line is we ran the furnace all night to keep our little house warm. I removed the OAK and no change (maybe just a bit more air, still under 540 max temp - we have a long run for the OAK) I'll look again, but didn't see/feel any knockouts, the bottom 4" hole is open and I can feel the air intake inside it to the rear. Only other thing I can think of is wood or something inhibiting the draft, but neither seems viable. Regarding the "punky" wood, I should elaborate. I've used this repeatedly to start fires. The majority (95%) of the wood is either dry beetly kill pine, or seasoned HW - mostly elm, some ash and a little oak. Down and split for >2 years, catches right away and no sizzle at all. We also have a prob. with coal buildup, which indicates further some kind of problem I think. I'm assuming that as we just paid decent $ for a stove, the dealer will offer at least a "check it out" service... Maybe he will notice something I missed. But not counting on it - thanks to you all I'm pretty sure your collective experience has hit most of the possibilities.