Good morning Dakotaman, I like to run all my boilers as hot as possible, to keep them burning as clean as possible, this is the reason for the brick lining in your B-L model, another benefit to running hot is to eliminate more oxygen in the water, running it hot will not hurt the unit as long as it does not consistantly boil at the top of it's cycle, watch for steam exiting the vent tube, if you see visible steam then back off the temp by 5 degrees, different elevations boil water at different temps so this is the best way that I have found to set the high limit temps. As far as the over run on the temp, please check to be sure you have no air leaks in your door gaskets if you do then please adjust the doors, they are easily adjusted on all sides, the extra stack is creating extra draft and may be pulling fresh air in through the doors, the over run may also simply be low heat load, remember you have a lot of poured refractory cement in that unit, once it gets hot it stays hot, with little heat load it may spike a bit but will not cause a problem as long as it does not go to steam consistantly. Now for the big question how do you like your new B-L series from Portage and Main, I can't sell them here but am dying for more feedback on it, I really like what I see and hear from my friend Dave who does sell them in Wi.