I honestly don't know. I haven't changed anything except switched to the heatmore . When it was 17 below I had to load it 3 times a day. Something must be wrong but I really don't know what. I know I cant do this another year
I found that by overloading the heatmor I loose efficiency. My first year I was going thru a lot of wood until I realized I was overfilling it. Unless I know I am going to be away for over 12 hours, I load less than full with good dry wood and it will be ok even in very cold weather. I use larger pieces of good heavy oak or elm on cold nights and lighter pieces of cherry or elm or rotten stuff on warm days. Sometimes when it is below zero I fill at 7 am, top up a little at 6 pm and full at 10 pm. The best place for the wood is down by the firebrick.
I have heard the same thing about loading techniques from Central Boiler friends, so you probably already know that.
The other thing I did to my Heatmor was add insulation. I think they are underinsulated. I taped bubble wrap insulation on the inside of both doors since it appears that is a major heat loss area. Insulate the pipes in back. I also pulled back the roof steel and found the fiberglass was not evenly installed and there were gaps and lots of airspace above. I added fiberglass to fill the voids being careful not to compact it. I think that helped on my wood usage. I know it helped some since the snow doesn't melt right off the roof anymore.
I heat a well insulated 1500 SF ranch (68°) with basement and 1100 Sq.Ft. attached garage (58°). I would guess I have gone thru over 12 cords so far this winter. Normal winter would be 10-12 cords total, but this winter has been very cold. I started with 4 or 5 cord box elder and light stuff and have had good oak, elm and maple thru all the cold spells. This is all good dry wood - generally I use wood: oak that has been stacked for over 3 years, dead standing elm with no bark or light maple or box elder stacked 1 year. Right now I am so far ahead it is all stacked and allowed to dry some and the box elder is always the newest as it tends to rot if it sits too long. A lot of it is split down to 12" size to fit in the door. I am cutting wood all the time, but getting ahead and having dry wood is worth it. The wet wood smokes more and I go thru a lot more of it.