You say it's a masonry chimney with a partial liner. I'm not familiar with stove operation with a liner but this caught my eye:
I've got a masonry chimney and if it's cold out and you are starting a fire from scratch it's gunna take you a longer than you think to heat up that chimney nice n' hot. Think along the lines of an hour plus to get it going properly. Plenty of kindling, keep adding small splits (I start with three to five small splits [small being 3" or less]), keep the front door cracked about 1/4" and don't let the draft suck it shut, let that partially burn down then add some more splits. Gradually increase the size and quantity of the splits as the intensity of the fire increases. If your wood is good, that should get you where you need to go.
It sounds to me that you are not letting the fire get intense enough for long enough before you cut the air down OR you have bad wood. Does the wood "hiss" at all after you add some to the fire?
The temp after 20 minutes or so is only around 225 degrees.
I've got a masonry chimney and if it's cold out and you are starting a fire from scratch it's gunna take you a longer than you think to heat up that chimney nice n' hot. Think along the lines of an hour plus to get it going properly. Plenty of kindling, keep adding small splits (I start with three to five small splits [small being 3" or less]), keep the front door cracked about 1/4" and don't let the draft suck it shut, let that partially burn down then add some more splits. Gradually increase the size and quantity of the splits as the intensity of the fire increases. If your wood is good, that should get you where you need to go.
It sounds to me that you are not letting the fire get intense enough for long enough before you cut the air down OR you have bad wood. Does the wood "hiss" at all after you add some to the fire?