Recirculating mash question

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Well-Known Member
Dec 21, 2007
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Oconomowoc, Wisconsin
O.K. I am designing my recirc system and think I will go for a HERM system. My question is concerned with pumping and filtering. I am planning on using a grant out of the MT but this is where my question comes in...

My thought is to place the grant ~12" below the MT and control flow to the grant with a ball valve mounted on the kettle. When the grant fills to the level of the outlet it feeds to a filter and then off to a pump for recirculation. My question is two fold.

1. During initial vorlauf of the mash how do you avoid grains clogging everything up (grant / filter / sparge arm / etc.)?
2. If you don't filter or use a grant, why not? Isn't this bad for the pump?

You can keep it simple by just using the pump without a grant or filter as the grain bed will work as the filter. The method you use for an inlet screen in the bottom of the mash tun will determine how fine you can crush the grain without sticking the mash. A worth while option would be a flow indicator in the pump outlet that will let you monitor the flow and set flow rate with a ball valve on the pump discharge. Here is a flowmeter from Dwyer that should work, VFB-81-SS with a flow range of 6-60GPH (.1-1GPM), unit cost is $47 and shipping from Dwyer. The fine grain particles that flow through when you start do not seem to bother the march Mag-drive pumps, and are usually cleared in a couple minutes of recirculation.