jharkin said:I wouldn't worry about black glass. Its a side effect of the VC design that has the cat in the back in that sperate insulated chamber. When you are burning VERY low, the firebox is just smouldering. All that smoke feeds the cat which is making almost all the heat on low burn. The smoky firebox will blacken up the glass but as long as the cat is working the chimney will stay clean.
For long overnight burns I pack it to an inch below the griddle and once the cat is lit I close the air to within 1/8inch of fully closed. Ive got 2 year old wood and burning like this it will sit with 350-400 griddle temps and around 1100F on the cat most of the night. (This is another area where the cat probe helps - you know not to worry about low griddle temps as long as the cat is reading over 800) Glass get black but after an entire winter of burning like that Ive never got more than a coffee can of ash from a cleaning.
+1 on the black glass. I get that with my Keystone if I cut it down to far. In fact, really the only times you will see the stove top go crazy over temp is if you have a cat only burn. The cat burns as hot as there is smoke available - so if you cut the stove down to much at the wrong time, get ready for 700 degree plus stove tops. I've hit 700 once on my Keystone, but that was a peak. I start paying attention when it hits 650-675ish. The way to cool it down is to open the draft and let firebox flames take care of some of the smoke burn.
You may have hit your low temp burn inspite of the black glass. That's the trade-off, but like your VC, my Keystone burns it off during the day when I open things up for more heat.
I know I'm kind of talking apples to oranges with my Keystone to your Encore, but I think they are similar in low cat burn technique and results.
Hope my comments are of some help.
Good luck,
Bill