Wyley
Knows what a fatty is.
You mentioned that you fill the water pan with HOT water. Is that HOT as in BOILING HOT. If not then you are using much of your heat energy further heating the HOT water that you start with to boiling. That could be why your fuel consumption is so high at the beginning. If you are going to use a water pan then you should start with boiling water and if you need to add more you should use boiling water for that also.
Paul
Paul