"This post is primarily for those of us with CM rigs, but hobbyists with other types of rigs may find it useful.

I started this thread to clear up a common misunderstanding about what is happening in the vicinity of the column condenser in a CM rig. Hopefully, it'll help us improve our techniques (or experiment with new ones) and lead to better overall results. I'll try to add some graphics later, if appropriate.

I'll start with a simple statement: [COLOR=""#FF0000""]You can't control the vapor temperature by making adjustments to your column condenser cooling water.[/COLOR]

Now here's why:

We all know that pure water boils at 100 C at standard temperature and pressure. When we start with a pot full of cold water, we put it on a burner, cut in the heat and it warms up. Once it reaches 100 C, we get our steam (water vapor),. If we increase the heat we can get more steam (more volume), but still the water remains at 100 C. Most of us take this fact for granted. It's just the boiling point (BP) of water.

The same goes for our washes. They have their own unique boiling point based on their contents. If we have a solution of pure ethanol (with a BP of 78.4 C) and pure water (BP 100 C) the boiling point of the solution is going to fall somewhere between 78.4 and 100 C. The actual BP of the solution will depend of the relative concentrations of the ethanol and water. For example, a 10% abv wash will have a BP very close to 93 C. You can find the BP of an ethanol-water solution by looking at a phase diagram.

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One common misunderstanding is that once our example 10% wash reaches 78.4 C all of the ethanol will vaporize and leave the water conveniently behind. This would indeed be handy, but unfortunately it's not how a solution behaves. This might be the case if all of the ethanol and water molecules were to spontaneously separate themselves -- with the pure ethanol occupying an invisible cylinder in the middle of our boiler. In which case we'd only need a drain and the entire distillation process wouldn't be necessary. But in a real solution all of those molecules are randomly (but more or less uniformly) distributed throughout the solution. And they're all attracted to each other by forces of nature.

So, when we heat up our liquid solution, we're adding energy. As we add energy the temperature rises and the attraction between the molecules diminishes. Eventually we arrive at the solution's boiling point and some of those molecules (both ethanol and water) manage to break free from the solution to form a vapor. Now comes a key point, the vapor will contain a greater volume of ethanol. If we were to condense the vapor from our example 10% wash we'd end up with roughly 53% ethanol and 47% water (again see the phase diagram).

Now, once we're at the boiling point of a solution the temperature does not change. All of that energy we're pumping into the solution is essentially trapped by the vapor. It's referred to as the ""latent heat of vaporization."" Latent heat is ""the heat released or absorbed by a body or a thermodynamic system during a process that occurs without a change in temperature."" It's the energy that changes the state from liquid to vapor.

By this point, you may be wondering what all this has to do with the column condenser. Well, the reverse process occurs during condensation. That is, the column condenser tubes remove some of the latent heat from the vapor (via a heat exchange with the cooling water). If enough energy is removed from the vapor (the latent heat of condensation), the vapor condenses. And here's where the next key point comes in: the temperature of the vapor does not change. Just like the temperature of our solution did not change once at the boiling point, the temperature of the vapor does not change either. And just like adding heat increases the volume of vapor production, removing more heat increases the volume of vapor condensation. If we remove enough latent heat, we'll knock down (condense) all of the vapor. So when we adjust our cooling water, we're simply adjusting how much latent heat we're removing. And the temperature of any vapor that makes it through the condenser remains unchanged.

[COLOR=""#FF0000""]All of this simply means that you can only control your collection rate with the cooling water.[/COLOR] The column condenser will indiscriminately remove latent heat from whatever vapor mix is at the top of your column. If you obtained good separation and just heads are waiting there, then you can condense heads. If you have smeared heads/hearts, then you will be able to condense smeared heads/hearts. But you won't be able to collect just the heads from a smeared mix by adjusting the cooling water any more than you'd be able to get the ethanol to flash off at 78.4 degrees in a 10% abv wash.

Regards,
--JB"

degrees F. = Degrees C. X1.8--- then add 32 to that amount

EXAMPLE 100 deg. C. 100X1.8= 180+32=212 Deg F.

the boiling point of water is 100 Deg. C. (((OR)) 212 deg. F.

Hi Scotty, I use the PSII tower. As the tower comes up to temp I only have the ball valve for my condenser water open about 1/8 turn. When the head temp reaches 150-160, idealy 155, I will open the ball valve somewhere between 1/2 and 3/4 open and turn the heat down on my burner. That stops the head temp from rising any further and that's where I hold it until the reflux stabilizes. I can tell when the tower has stabilized as the head temp settles down and quits fluctuating back and forth.
Once it has been stabile for 1/2 to 1 hour I will decrease the water flow to the tower and let the temp increase to 165-170 and pull the for shots and most of the heads off.
After that the temp will start rising on it's own and usuall stabilizes between 173 and 176 until the alcohol in the wort/wash decreases to the point where the temp starts to rise again. At that point I will increase the water flow and maintain the head temp below 183 as long as I can.
After the temp reaches 185 I will cut the tower water back to about 1/4 to 1/2 flow and let the temp rise up and collect the rest of the tails until 190. That's where I quit.
Don't know if the way it's supposed to be done but I'm getting 90 to 92% on a consistant basis, sometimes 94%, but never hit the fabled 95%. YET.

Have Fun.

Scotty, I read one of you post somewhere talking about 4000w element on 110v. I am building a VR and plan on using 2x 2000w 110v elements. Will this work? And what is the deal with using a router controller to control them? I hear mixed emotions on this. Will a router controller give me the control I am looking for? Thanks.

As a pot stiller, I can get a pencil-thick stream out of my still with no problem with a single 1500w internal heating element. I understand that a reflux still is a different animal, but wouldn't a little bit of insulation on the column help?

"

Ive been thinking about what insulation does to a still tower. It not only prevents drafts from messing up your temperature but i believe that the other very important reason is that it will prevent condensin from occuring on the inner wall of the tower, This woild cause liquid to roll back down and miss the packing and greatly reduce the refluxing effect."

10 gauge - just like a goose gun

Found the post bigwheel mentioned

I'm not sure you can pack them too tight by hand. We are talking steam here & pressurized steam wants to find a way out. I used the BH rolls of copper & have 4 of them in my full column. They are not loose enough to fall out. I then jam the 8 pot scrubbers in between the reflux tubes. Now that is something I do, it wasn't suggested by anyone, so it may be superfluous.

"Gee take a look of that! I knew it, oh common!
Read this and you'll be shocked as I was.
http://pipublic.com/?23465"