So had my boiler serviced last week and the back of my fire box (combustion chamber?) has insulation on the back side that has fallen forward. This keeps the flame from heating the deeper sections of the boiler itself. Thought on how this would affect the efficiency of the boiler? I know that the last season wasn’t too cold but my bill was quite high and I believe that it most likely is due to having this kaowool board hindering the flame and it takes longer to heat up? Thoughts?