Hmm, agree with most above re placement of the probe nearest to the hottest point of the closed system. A few things I would try. Use a rounded volume of around 2.75 - 2.8 L/kg. Add water to the tun and begin recirculation, when the recirculating water temp is stable at your mash temp add the grist and stir only a few turns. After 30 seconds to allow for grits and flour to clear the pump head throttle back the pump output to prevent compaction of the grainbed (I use about 1/4 throttle). Temp will drop back slightly after adding the grist, once the recirculating wort is back up to temp start your mash timer. My best eff 92%+ comes at 75 min rest length, 90 min gives no further improvement, 60 min results in lower eff. After the timer goes off at 75 min lift controller set temp to 77C for the mash out rest. After 10 min or so check recirculating wort temp, if up to mash out temp (77) give the mash a few gentle turns with the mash paddle then set the timer for a 10 min mash out rest. I continuous sparge with water at 77 pumped via the HEX to maintain temp while gravity draining at .5L/min to the kettle. If batch sparging add sparge water as normal.
Watch mash times, there is a sweet spot with all systems, lengthen out the sacch rest time by 15 min, if you note a gain in eff lengthen again by another 15 min, repeat until there is no further increase in eff. Be sure your recirculating wort is at temp before starting the mash timer. Recirculating slowly reduces channeling and allows for a more open grainbed. As you will now not have high combined temps you should notice a marked improvement in attenuation.
Cheers,
Screwy
:icon_cheers:
