Just started running a 503 insert a month or so ago. Our house is 2850 Sq.Ft. two story ,built in 1839. We have replaced most all of the windows in the last 5 years.36 in. of insulation in the attic. In other words, a spruced up old farmhouse.
The house has a forced air furnace,so we use the house fan to distribute the air. In addition,we put a floor fan at the base of the stairs when the temps go below 20 Degrees.
We have had no problem keeping the upstairs 67-70 in the coldest weather,and we hit lows of 4-6 below on a few days too.
On the coldest days we used a good 80lbs. a day. Currently,with the warmer temps.30's to 40's,the use is cut in half.
Speaking as a rookie on burning Anthracite,I am quite satisfied with the 503 insert.From the ease of operation,to the general appearance of the unit.(welds looked good to me)
As i just had a face plate fabricated and installed,i will try to post a photo now that the job is complete. Looks cool...........