That's curious considering it's made in WA. Pinging
@BKVP on this question.
The big Kuma is a nice looking insert. Here is a recent post about this insert that you may find helpful.
https://www.hearth.com/talk/threads/kuma-sequoia-insert-install.140772/
The Princess insert does not have a provision for a fresh air kit. As for states that do not permit inserts to be sold if they do not have a fresh air kit, that I will look into. ( It is the law in all 50 states for mobile home solid fuel heaters) As for burn times, I have mentioned this before but here it goes again.
Our burn times always (90%+) exceed other units, regardless of shoulder season or dead of winter. Respectfully to BeGreen, the thermostat in our units provides a more even heat out put as a result of the continual adjustments taking place.
Look, cord wood is not a metered fuel. It's really that simple. When you have a stove that requires humans to adjust the amount of heat produced by the stove and you care to remember cord woods very nature and how it burns.
Put a thermocouple 30" above the flue collar of ANY stove with a manual air control, load 30lbs or whatever will fit into the firebox. Set the air control immediately to where you like it. Now go away for 6 hours. A chart recorder attached to the thermocouple will show erratic heat outputs. Not because of the brand name but because of the technology of a manual air control and the inherent way cord wood burns. By the way, we have done this many, many,many, many times. If you sit in front of the same unit and repeat the test, but include a digital reader and make continual adjustments to the manual air control, you can increase the burn times on EVERY SINGLE UNIT WE TESTED.
Do the exact same experiment with one of our stoves. You'll thank the Lord above the line is not your EKG! When you set the thermostat to the desired heat out put. 6-40 hours later check the chart recorder. Flat lined until it runs out of fuel. Think of the thermostat as a shock absorber.
Now this post might get censored because it is considered "promoting", but it doesn't change it from being thruthful.
Hopefully it will not be removed because it is in direct response to the question posted here in this thread.
By the way, we manufacture two manual air controlled units and other they both have the same erratic heat outputs as every one we have ever tested, and they say BK on them.
