I had a 20 mile overnight hike this weekend and decided to give my Esbit stove a try since I only needed to heat 2 cups of water twice. I had some issues with it and I'm wondering why. First the stove itself wass the foldng model that esbit sells. Second the fuel used was a brick of esbit fuel purchased just a few days before at REI. The brick I'm referring to is the one that can be divided into 4 smaller bricks. I used a full brick. I attempted to heat 1.75 cups of water in a Snow Peak titanium pot (tall one) with a lid. I didn't use a wind screen of any sort because there was no wind at all. The air temp. was about 50 degrees. I don't know the water temp but it came from my water bottle and it was probably close to the air temp.. So, I lit the cube and let it burn. It burned about 12 minutes and the water wasn't boiling, although it was hot. I used a second cube and finally got the water boiling.
I was pretty disappointed with the performance. I used all esbit stuff and followed their instructions (as far as I could tell) and it took more than twice the fuel requirement Esbit says you need to boil less water than they specify 1.75 cups versus 2 cups). I still had a hot dinner but had to wait forever for the water to boil and used twice the fuel I expected top use. If it was super cold or windy or anything like that I could understand, but I had near ideal conditions aside from the startinmg water temperature.
Can anyone provide some ideas why I may have had these problems? I really liked the esbit for a short backpack otherwise ... light and simple.