Sorry, been busy over the holidays and hasn't been cold enough here in Ontario to burn much.
After two attempts I got my replacement air door from SBI (no charge) so service was good.
I've been getting to know the "personality" of the Heat pro over the last two weeks and I'm very happy with it. It does behave a bit different than the old Tundra ... but different doesn't mean bad.
The Heatpro throws great heat, more than the Tundra, and flows a TON more air. (Better ducting hookup is key)
For caparison at -10C the old Tundra would heat on it's own for 6-8 hour stretches, without propane assistance, with house temps going from 65 -70 degrees. Anything colder, propane was coming on after 4-5 hours. At -20 C the Tundra struggles to reheat from 65 to 70 and usually the propane was used to speed up the process.
The Heatpro at -10C easily holds an 8+ hour burn with coals, and the house is still at 67 in the morning. Reheat from 67 to 72 ... about an hour. THAT's the best improvement. Only had two nights of -20C, and if the propane came on, it wasn't for long. Also, the re-heat time was still very fast.
The down side ... I'm burning more wood. I think the wood usage in moderately cold temperatures would be very similar but for off season milder temperatures the Heatpro uses much more.
Getting the firebox up to temperature is critical to getting good efficiency out of the Heatpro. Small fires, don't get hot enough for good secondary combustion in the Heatpro, so you send smoke/ heat up the chimney. Alternatively you can have 10 deg. temp swings in the house burning full loads every 12 hours. In milder temps I'm also using up lots of kindling wood starting a new fire as I let it go out completely to let the house cool off a bit.
I was having coaling problems with the Tundra, not with the Heatpro. It burns every coal to dust and I'm removing far less ash from burning more wood. (likely due to my exterior chimney being kept at a high enough temp for good draft by the larger pile of coals.)
I think the best way to handle off season burning of the Heatpro is with full loads of low BTU wood. There is a cedar mill that sells slats and off-cuts in a bundle about an hour from my house. Filling a firebox with nothing but cedar would likely heat my house in milder temps for 6 to 8 hours. That in itself is awesome.
Even with full loads of dry wood the Thermo-couple temp rarely is above 150deg F on the fan control. The blower spends most of the first hour of a big fire on fan speed #2, and the rest of the time just on Speed #1. The last 2-3 hours it cycles on and off. Even on speed #1, LOTS of heat is being pumped into the house.
Overall, I'm very happy. I'm glad I went with the bigger replacement and so far it suits my needs perfectly. Now excuse me while I go cut more wood to feed the beast.