Medal Winners - Post your system!

[molc]

I thought the transfer into the FV after cooling would be enough aeration? I'll shave down my plastic spoon thing to fit it into my drill for the next brew. In the video above it looked like an STC was controlling the element for the HLT, I didn't know it would be able to handle the 2.4KW element - if it is I'll use one to control the mash temp more accurately than using my thermapen and manually turning on and off the element as I tend to overshoot the required temp.

STC is rated for 10A, which, if I remember correctly, is in the region of 2.5kW max draw.

[biertourist]

I thought the transfer into the FV after cooling would be enough aeration? I'll shave down my plastic spoon thing to fit it into my drill for the next brew. In the video above it looked like an STC was controlling the element for the HLT, I didn't know it would be able to handle the 2.4KW element - if it is I'll use one to control the mash temp more accurately than using my thermapen and manually turning on and off the element as I tend to overshoot the required temp.

STC is rated for 10A, which, if I remember correctly, is in the region of 2.5kW max draw.

Yep 10Amps @ 240 volts = 2,400 watts  (10x240=2,400). -But of course if your voltage in your house actually measure say 230 vs you're down to 2.3 kW but still plenty for a 5 gallon boil.


Adam

[biertourist]

Bear with me here for a minute, I've been brewing a few years but still consider myself very much a novice. I have a fair bit of experience of dissolving gases in water from my normal life and I'm going to take an educated guess that the same principals apply to wort as to water.

Oxygen will naturally dissolve into water under atmospheric pressure but there is a limit on the amount, we'll call this 100% saturation.
The amount of oxygen it takes to get to 100% saturation depends on a few factors; temperature, pressure and whatever else is already dissolved in there.

Cold water can hold more oxygen than hot water, fresh water more than salt water, water at sea level more than at the top of a mountain. There are big tables to show you what amount of oxygen water can hold for these given parameters.

We can push the oxygen content over 100% and 'supersaturate' the water, we still measure it as a % of what it will hold under normal conditions.
e.g. the same principal applies with carbon dioxide when we condition our beers, we have 100% saturation of CO2 due to the high pressure inside the vessel keeping it in solution, when we release that pressure the saturation potential of the beer drops sharply and the beer becomes supersaturated and comes out of solution and we have fizz. Simple (I hope).

When it comes to fermenting wort we will not be fermenting it under pressure (or most of us won't anyway) and the temperature will remain constant. By using pure oxygen in the wort it is possible to get the saturation level above 100% and if we don't disturb it it may stay like that for up to 24 hours, but it will come down to 100% on it's own without any other factors in that time period (assuming it behaves the same way as water). This isn't really long enough to have any effect on the yeast I don't think.

The next thing to consider is what happens when the yeast gets active, it produces CO2 which will start to form bubbles once it gets over 100% saturation. This bubbling of the CO2 will strip out any excess oxygen extremely quickly leaving it back at 100% saturation (until the yeast starts to use it up), for practical purposes for homebrewers I'd nearly call it instantaneous.

Aeration (splashing, vigorous stirring, whisking, bubbling air) is actually pretty good at getting water up to 100% saturation but the one the you have to be aware of is the temperature. If you go through your aeration procedure before the wort has fully cooled then you may leave your yeast short of oxygen. You could get your wort to 100% saturation at 30 degrees but then as it cools down to say 21 degrees it may only be 80% saturated making it much harder for the yeast.

What do I do? I get my beer down to 21 degrees and let it slowly cascade into my fermenter, the drop is about 20cm from the tap to the very top of the fermenter so it gets a good drop. I sometimes also give it a very vigorous stir with a whisk just to make sure. I got a loan of an oxygen meter from a friend and measured it in the past and it was 100%, happy days.

With regards to putting air/oxygen through a stone in the wort, to get the best efficiencies they need water pressure above them to force the oxygen into the solution. In practice you need to make sure they are at least 30cm below the surface or most of it will just vent off.

The one advantage using pure oxygen over air will be speed, using pure oxygen will get you to 100% saturation quicker than air but that's personal choice.


Now waiting for Will to shoot me to ribbons and show me up as an idiot! 

Great discussion but weird in a "Medal Winners" thread -moving to a new thread to discuss oxygenation in wort: http://www.nationalhomebrewclub.com/forum/index.php/topic,9303.0.html