Originally Posted by CBMbrewer
Without the aid of a gravity feed I mashed out using my pump.
I also have to use my pump to sparge, which does not have any speed control so it comes out at about 7.5 gallons a min (I'v tried adjusting the valve).
So at what point during the mash out do I start sparging and how can I reduce the flow to what amount of sparge time?
Also, should I always leave the kettle uncovered for the boil (in the past I have had too much boil off so I have gotten in the habit of leaving the kettle half covered)?
Well, I do a mash out, and fly sparge, and I also do a thick mash like you, but I use gravity rather than a pump.
For English beers (which accounts for about 90% of my brewing), I dough in using 1 qt per lb. For American beers, I use 1.25 qt per lb, and for lagers, I use 1.5 qt per lb. I mash the English beers for 90 minutes at 150F. Other beers get mashed for 60 minutes at 152 - 153F. At the end of the mash, I do a mash out by adding about 5 - 6 qt near boiling water and stirring it in really well. For a thick mash, this raises the grain temperature to about 165 - 168F. For a thinner mash, the grain bed temp is raised to the low 160's.
I then leave the mash out for 15 minutes before vorlaufing, and then starting the sparge. I do not drain the first runnings before starting the sparge.
I then sparge by slowly adding the sparge water, and draining into the kettle. This usually takes me about 60 minutes for a 5g batch, but may be as long as 90 minutes for a high gravity batch. During the sparge, I monitor the gravity of the runnings using a refractometer. If the gravity drops below about 1.008 before I have collected my pre-boil volume (which it usually does for brews with an OG < 1.050), I stop the sparge, and add water to achieve the pre boil volume.
Depending on what equipment I am using, I achieve 80 - 85% mash lauter efficiency using this method. If I were to sparge in 15 minutes, my efficiency would drop considerably, and I would almost certainly collect excess tannins due to the channeling.