I have the 22 insert I. My comments are bitter /sweet for you. After reading the manual and a little learning curve I found the stove to run very well, generating good heat. The downside’s I feel you are aware of but have not addressed them? May be wrong so I will list them. In the manual option I get low temp when pellets run out even when I have a quarter bag of pellets in the Harper. They lay on the side’s and don’t feed to the auger. Your Harper is too small have to feed the beast every day. Glass fog’s up. Pulling the rod to clean the heating tubes can only be done when cold and with great difficulty. It’s clear the tolerance’s are off and have not been fixed. I thank you for replacing the vacuum which died after three cleaning. May I suggest placing a filter paper around the screen to prevent the main filter from being clogged so heavily.