Heat exchanger eh, so do you pump the mash water through it or do you submerge it in the mashing water in the tun? Do you have a picture possibly?
Very interesting indeed. I take the mash water to 155* and add corn then run the agitator until it's broke down, adding heat when necessary to keep it at 150-155*. Then I add enzymes and continue agitating for a bit and letting cool. Then wrap in blankets and let it slowly come down to pitching temp. (usually the next day, 12hr's or so later)
But if I understand you correctly, your taking it up to 200 and shutting off the heat, adding grain etc and doing your mashing as the temp drops. If your getting 11% it's obviously working. (you must be higher than 2lb's per gal to get that right? I'm getting complete conversion according to my iodine tests but at 8-9%)
Now I'm tempted to try 200*, I've never gone higher than 155* as the saccharification temp for corn is 145*-170*....crap... I'm realizing as I write this I've mistaken saccharification temps for gelatinization temps. Now I understand why I've seen others post they go to 200*. Huh, go to bed tonight a little less stupid!
So, if you're using a screen to get the liquid out, how do you get the spent grains out of your mash tun?