Dry fire and flow rate

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cchristoph

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I’m about to have my first brew day this Sunday in many years. And my first ever being 100% electric. EBiab built from @Bobby_M design.

How can I gauge flow rate visually if I’m trying to hit 1.5 quarts per minute? My main concern is dry firing the element. How will I know if/when the element dry fires?

Using a wilser bag, 15G kettle, false bottom, and riptide pump feeding the whirlpool and recirc on top of the lid. Planning a 5 gallon batch.
 

doug293cz

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Fill your kettle with water, disconnect the pump output hose from the kettle, and experiment with pump valve settings while filling up a vessel with volume markings from the pump outlet hose. Count how many turns from closed you need to turn the valve to get the flow rate you want. You might want to target a slightly higher flow rate with water, since wort will have a higher viscosity and pump a little slower.

Brew on :mug:
 

Bobby_M

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The trickle through the recirc hose should be like 3/8" in diameter. Set a timer and see how long it takes to fill a 1 quart measuring cup. It should be about 1 cup in 10 seconds.
 

eric19312

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Is your concern regarding dry fire that you might get a stuck mash and pull the space under the false bottom dry? I've struggled with recirculation in past and had a period of time where I was frequently getting stuck mash. I was using a Wilser bag at the time on top of a Norcal false bottom. Over time the bag seemed to get less and less porous and hit a point where it would quickly plug almost irrespective of the grain crush.

Having some way to visualize flow rate during recirculation was really nice when dealing with this issue. I used to use a rotometer and that worked great. Got a plastic one off ebay for about $20 that said it could tolerate 170F which was ok for my mash tun. But started using my pump a little differently and needed to be able to run boiling wort through that segment and so I got rid of the rotometer and put a sight glass on the kettle below the false bottom. This doesn't tell me how fast I'm flowing but it does tell me if mash is starting to stick. In the end I ditched the bag as it wasn't really needed brewing three vessel but I still use that sight glass to keep eye on my recirculation.
 

Bobby_M

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on top of a Norcal false bottom.
That's really the problem. When a bag sits on top of a false bottom, the effective open area becomes the same as the false bottom itself, i.e. where the holes are. Typical perforated false bottoms have an open area of only 33%.
 
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