Using a Magnehelic gage for my low draft test, I'm getting readings of 66 high and 62 low draft with the combustion blower speed set as low as it will go.. In the Harmon book, it states it was set to 50-55 high and look for 30-35 low. I'm nowhere near those #s. What am I gaining or loosing with those #s. How does it effect the stove in terms of burning at peak performance. Can it be changed? I have not completed my yearly tare down and Im wondering if a dirty stove will cause higher #s. Any suggestions ?