stir plate blues

Mon Aug 15, 2011 7:12 pm

So, a buddy and I brewed 10 gallons yesterday. We made starter wort in my 5L erlenmeyer and then split it into our 2L erlenmeyers and pitched 2 vials of White Labs Cal V each. We each put them on our stir plates at my place and left them there for a couple days. On Sunday we pitched and he texted me this morning letting me know his beer was blowing off already.

I brewed 10 gallons, he brewed 10 gallons and we each got 5 gallons of each wort for a total of 10 gallons each. Both his beers are blowing up and mine haven't done shit. Literally ZERO sign of fermentation. I'm not freaking out yet as it's only been 24 hours, but it is a bit unnerving that his beers have taken off and mine haven't and they're both at very similar temperatures.

I have this same stirplate (and no, that's not me trying to off the thing :D). It only has an on/off switch and an RPM dial, but when I took my starter off the stirplate I noticed there was a decent amount of heat that it was giving off.

I'm guessing my stirplate cooked my starter and that's why I'm seeing zero signs of fermentation and my buddy's beers are going strong.

Based on this. I've decided I need a new stirplate. Regardless of how easy they are to make, there's no way I can make one. I'm not handy, I don't understand electronics, I can't solder and I'd just rather buy one that build one.

So, I've looked on eBay, http://www.BrewersHardware.com, B3, Northern Brewer Midwest Supplies, Williams Brewing and Nikobrew. They all have stirplates between $40 and $200+.

I don't plan on making many starters in my 5L flask, but it would be nice to be able to should I ever need to do so. Does anyone have any recommendations or experience with a <$150 stirplate that can handle a 5L flask, a 2L flask and won't get hot?

Thanks in advance

Matt
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Re: stir plate blues

Tue Aug 16, 2011 8:21 pm

How hot did it actually get?

If the yeast is just in its growth stage the higher temp can be beneficial.

My stirplate warms smaller volumes up to around 30deg C sometimes, and I have not had issues with pitching. Large starters I usually chill and decant off the 'beer' first though.

Also were your yeast vials the same date as your mates?
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Re: stir plate blues

Tue Aug 16, 2011 10:38 pm

If the temp gets a bit over 120F there is a very good chance the yeasties have been cooked. Think of the analogy of sitting in a warm hot tub that keeps getting warmer over a 12 hour time period. Youl'd never feel it but your ass would be poached!

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Re: stir plate blues

Wed Aug 17, 2011 5:51 am

They all add heat to some extent. The motors are not 100% efficient in any of them.

You can try insulating the flask from the stir plate using anything that doesn't conduct heat very well such as a sheet (or sheets) of glass, plastic, carboard, paper, wood etc. Obviously if you use too thick a piece of insulating material the coupling between the magnet in the stir plate and stir bar gets too weak so you may have to experiment a bit. The thicker the better from the insulating point of view.
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Re: stir plate blues

Wed Aug 17, 2011 12:37 pm

I got mine from http://stirstarters.com/ Good Service and great product.
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Re: stir plate blues

Wed Aug 17, 2011 1:40 pm

ajdelange wrote:You can try insulating the flask from the stir plate using anything that doesn't conduct heat very well such as a sheet (or sheets) of glass, plastic, carboard, paper, wood etc. Obviously if you use too thick a piece of insulating material the coupling between the magnet in the stir plate and stir bar gets too weak so you may have to experiment a bit. The thicker the better from the insulating point of view.


The thicker the better only within the same type material. Selecting a thinner material that is a better insulator will prevent more of the heat from transferring than a slightly thicker material that will conduct more. In the past I've used a sheet of styrofoam packing material (less than 0.5 in thick) and it seemed to do the job, I have an older model stirplate as well.
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Re: stir plate blues

Wed Aug 17, 2011 4:00 pm

I used to have the same heating problem with an old stir plate I used to have. I used a square cut from a silicone baking sheet liner. Thin enough to not interfere with the magnet, yet insulated the flask from the yeast.

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Re: stir plate blues

Wed Aug 17, 2011 8:07 pm

so, both batches were fermenting when I got home from work last night. I'm a bit stumped, but I'm still thinking that the stir plate killed most of the starter off. Fermentation seems to be going pretty good right now though.

If I had to guess, I'd say the temperature of the starter was above 100F when I took it off the starter. The expiration date of all 4 vials was mid November, but with living in SD and using WLP yeast, we don't often see old vials.

I still think I'm going to look for a new stirplate though. Anyone have one that'll handle a 5L flask?
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