I finally bought 2 pallets of the large Envi blocks. I have found that the Hearthwise burn approx an hour longer but considering the price, I guess from now on I'll buy the Envi. They give really good heat and overall, I am pleased with them. The Hearthwise cost me almost $1200, with delivery, for 2.5 pallets; the Envi cost me $613 for 2 pallets, with delivery. So it's a major price difference.