i have just installed my hearthstone. i filled it up with 2 year dry wood. started the fire keeping the door open for 10 mins untill things were going. shut the door air intake full open for another 20 mins. slowly start to shut off air intake (about a cm every 5 mins) but when i get to about have way there is hardly any secondary burn just fire in the box. until i shut the aire intake to about 3/4 and then the fire starts to die down with hardly any secondary burn. are my tubs cloged?!? how do i check? ty all for your help