New HI300, need advice

We had an HI300 installed on Dec 15. We're not getting the heat we expected. We can get the room temp up to 73 ish, but that's as hot as it gets, and it doesn't stay there. We're still getting the curing-enamel smell when it gets all the way hot, after 2 weeks of use. We have a 2000 sq ft colonial, and we have a curtain hung to block the upstairs and also keep the door to our back room closed. Our home isn't tight, but we have draft blockers in the doors and windows, and the temps haven't been below the 20s.

Our dealer/installer is saying it's our wood, but we believe our wood is good, and we burned a day's worth of kiln-dried prepackaged wood from Lowes without any improvement.

A full load is lasting about 3 hours, and everything is embers by then. We can't get it to stay hot all night, although there are enough embers to restart in the morning. But then it takes a couple of hours to get the house back up to 70 (we have our furnace set to come on at 60 overnight.) We're also producing a lot of ash; it needs to be emptied ever couple of days. We've followed instructions here about how to load, slowly closing off the damper, etc.

I read a great thread here, and suspect our trouble is that there is no insulation on our liner. We have a 25+, external chimney. Our dealer/installer said that the install kit came with an insulated blanket that they didn't use. The front of the stove is also off-kilter. One of the side pieces is crooked, and the hinge-side of the door rubs enough that the enamel is scraped off. They are willing to come back to straighten the front and lay on the blanket, but that's it.

I called another Hampton dealer in our area to ask if they'd insulate the liner for us and install a block plate. They said they'll need to replace the cap, and will install insulation at the top of the chimney only, for just under $400. They said they install about 100 of these per year with this method, and the only complaints they get are that it's too hot!

Thanks for reading. I want to be nice and toasty. We'd appreciate any advice

We leave the damper wide open until all the wood is burning well, then close it a small amount every 10-15 minutes. If I close it too quickly, we get black smoke out the chimney and the fire starts to smolder rather than burn, so we open it up a bit again.

The insert does have a blower, and it's on auto. We turn it to the high setting when it's really hot.

We generally do not close it all the way down and almost always have the fan on (except when starting up each AM). When all the way closed and/or the fan is off, we don't get much heat output. Sitting 3 feet in front of the stove you can feel heat. Six feet across the room, not so much. So we use the fan for heat output, and since the fan is on, the damper is open at least a little.