In the spirit of learning from others mistakes, maybe this will help someone out. Right in the middle of supper here tonight, the wind knocked the power out. This was about a half hour after I started my daily burn with the usual 1/3 or so starter load. Didn't pay any attention to the boiler since it handled this without a blip last year, and we were in the middle of a meal in the dark. So about another half hour later after I dug out the backup lights & while we were cleaning the kitchen up, I realized I was hearing some noises I shouldn't be hearing. So I tore downstairs to find things kind of warm - right about the boiling point at the top of the boiler. Long story short, and as far as I know, sometime between last year & tonight I had some air accumulate in the section of piping right at the top of the boiler that connects that to my upstairs zones with a NO zone valve in between. When the power dropped out & the valve opened, that released the air into my upstairs zones & airlocked them. Eventually and after a short period of 'oh crap', one finally started circulating with a bunch of gurgling. That kept the heat at bay, together with what was making it through my loading unit. I didn't really want to try to bleed anything then since our well tank only holds 5 gallons & we might have needed the water for something else & I didn't want to lose pressure on my system. The power finally came back on an hour ago, after which I spent a half hour getting the airlock out of my zones. That went in circles because on the first try, I pushed the air from one into the other. Anyway, all is well again - except our 'hi-speed' internet is still out & I'm on dial up right now. The price for living in the woods, I guess. Time to go to bed anyway. So - regular exercise from here on out.