I have a fireplace xtradinar apex 42. My question is burn times and heat output. On a full load of dry hardwood I get the cat temp up to around 800° with damper closed and air regulator fully open. And then I slowly start backing the air down to about 40% open. And cat Temps will come down to 600° and only put out good heat for about 3-4.5 hours then it's not really heating much. Only a small spot where the flame is almost touching the cat is red nothing else. Unit is 3yrs old and I regularly clean the cat. Woods I've used are red oak, walnut, ash, hedge and mulberry. All 25% moisture or less on a fresh split.
Picture is after 2.5 hrs after a full load
![[Hearth.com] FPX42 Apex Burn times [Hearth.com] FPX42 Apex Burn times](https://www.hearth.com/talk/data/attachments/323/323343-0a070b0551b647a59c990e5dad024ee5.jpg?hash=nZn4FtDzl7)
Picture is after 2.5 hrs after a full load
![[Hearth.com] FPX42 Apex Burn times [Hearth.com] FPX42 Apex Burn times](https://www.hearth.com/talk/data/attachments/323/323343-0a070b0551b647a59c990e5dad024ee5.jpg?hash=nZn4FtDzl7)