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Author Topic: Electric BIAB Mash without Circulation  (Read 1749 times)

Offline Kochhandwerk

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Electric BIAB Mash without Circulation
« on: October 09, 2018, 10:13:15 am »
Hi folks, it's been awhile since I brewed and much longer since I posted, so it's great to be back.

I just converted my 8 gallon brewkettle to electric using the Clawhammer 120v kit (I think a dang good deal for $240 including controller and element).  I have the heating element, ballvalve, and thermowell all about as low as possible on the kettle, and a 3" inch tall flat false bottom (with legs) covering it all. The holes on it are not grain basket small but maybe a millimeter or two.

I am still planning on using a regular grain bag for mash, but I'm wondering if I can utilize the heating element/controller to maintain mash temp rather than wrapping the thing with towels after I mash-in and hoping for the best per usual. Do you guys and gals think it'll be fine to run without adding circulation from the ball-valve back through the top? I don't have pump nor a port in the kettle lid/top.  My BIAB mash is always super thin (I do full-volume water mash) so I'm hoping this will work without circulation and the bag is definitely protected from the element but the false bottom.

Online Richard

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Re: Electric BIAB Mash without Circulation
« Reply #1 on: October 09, 2018, 10:52:50 am »
I do something very similar, but without the false bottom. Without a pump you will get some stratification unless you stir often. You can also have problems with lag time that will make  your controller overshoot and oscillate, depending on the distance from the heating coil to the temperature probe. The heater comes on but it takes some time for the heat to rise to the probe. By the time the probe heats up and the controller turns down the power there is already enough heat put in to overshoot. Most PID loops really don't handle transport lags like that very well at all. Stirring or recirculating smooths out all the temperatures and solves that problem. Lots of insulation also helps because the amount of power you need to put in is very small, so any overshoot and oscillation will also be small. I use three layers of Reflectix (https://www.homedepot.com/s/?search=reflectix ) during the mash that I remove afterwards. I am able to maintain mash temperatures with a low enough power input that I don't worry about burning the bag, and I can achieve a temperature stability of 0.2 - 0.3 F.
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Offline Kochhandwerk

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Re: Electric BIAB Mash without Circulation
« Reply #2 on: October 09, 2018, 11:02:54 am »
Thank you for your input, Richard. I actually installed the thermowell at roughly the same height as the heating element (below the false bottom) but as far away laterally as I could get from the element. When I ran a test last night the water at the top and bottom of the kettle were within a degree or so of each other (obviously grain/wort will make a difference). 

Since the water temp at same depth as the element is used for the probe, I'm hoping the odds of overshooting my desired mash temp are lessened, but what I'm hearing is I don't have to worry about any of this stuff if I just recirculate. I'll do a batch with this to see how the efficiency compares to my old BIAB setup and if it's not good I'll get that pump.

Online Richard

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Re: Electric BIAB Mash without Circulation
« Reply #3 on: October 09, 2018, 11:56:08 am »
I chose to go with insulation rather than recirculation. Cheaper and easier to clean. I also noticed differences between water tests and real mash behavior. Eventually I decided not to stress over fractions of a degree.

I'm not sure any of this will really change your efficiency. It is more a matter of getting the fermentability you want by controlling the temperature.
Original Gravity - that would be Newton's

Offline Kochhandwerk

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Re: Electric BIAB Mash without Circulation
« Reply #4 on: October 09, 2018, 12:08:47 pm »
Just bought some of the insulation you brought up. Since it's electric-fired I don't even need to take it off during boil and i'll also help heat up quicker since the 120v element leaves a bit to be desired.  Thanks again.