operating a VM/LM combo reflux

[pynys pub]

I've been operating my beer keg boiler ,thumper still for the last 3 yrs. now deciding to move on to a LM/VM column reflux . So I've read lots of reading but my questions are unique .
1 - I have a thermometer probe inserted under one of my slant plates for the LM side. Do I need another thermometer probe for the VM side? If so, where would I weld in a coupling? Before or after the globe valve?
2 - I was told that collecting on the LM side before switching to the VM side is just for collecting heads. So when I finish collecting the heads on the LM side, do I shut the chilling water off on the LM side and just run water on the VM side or do I continue to run the water to the upper condenser on the LM side?

I've got a pretty good feeling what needs to be done but would rather ask for much valued experience. Looking forward to a response.

Thank you.

[Setsumi]

Your reflux condenser is for reflux. You need reflux regardless LM or VM. Without reflux you will have a tall packed potstill. Personaly I would stick with one head, either LM or VM... then again I would opt for CCVM, but that is just personal preference.

[Salt Must Flow]

VM typically has a thermowell between the vapor takeoff and the takeoff valve.

You want water feeding the reflux condenser otherwise it will function exactly like a pot still with a tall riser. You want reflux for sure. The product condenser needs water flowing through it just before you crack open the VM valve in order to condense the vapor.

Is this build 100% completed? If not then I'd start operating the VM column just as is and later fool around with LM only if you feel the need. I've read a LOT of topics about LM/VM combo columns and most have ditched the LM portion completely. VM is just so darn convenient that most don't feel the need to fiddle with LM at all.

I'd also disregard any recommendations to mess with CCVM because it would be a silly downgrade from VM. Operative a valve is far more convenient, repeatable and precise than fiddling with raising/lowering a loose reflux condenser. It just wouldn't make any sense at all.

[pynys pub]

Ok thanks a bunch . I will be adding a coupler after the gate valve where I will be throttling the vapor for the VM and I will leave the top condenser water running after heads are complete to ensure the reflux process continues.. The only reason I added the LM side is because I was told if you just run VM , that it is known to smear the heads into the hearts when you get to that stage . Not for me to say , just learning so learn I will .
Thanks again

[Salt Must Flow]

Ok thanks a bunch . I will be adding a coupler after the gate valve where I will be throttling the vapor for the VM and I will leave the top condenser water running after heads are complete to ensure the reflux process continues.. The only reason I added the LM side is because I was told if you just run VM , that it is known to smear the heads into the hearts when you get to that stage . Not for me to say , just learning so learn I will .
Thanks again

I doubt that is true. You're either taking off condensed liquid or you're taking off vapor to be condensed. With LM, just as VM, you can only take off so fast. Any excess reflux/liquid overflows and falls onto the packing. Any excess vapor will be condensed and fall onto the packing. I ask ... what's the difference? If there is any difference, I don't see how it could be at all significant and if that's true then the convenience of operating in VM is well worth while in comparison. Just crack open the valve and take off your foreshots. Crack it open a bit more and remove the heads. Crack it open even more and take off the hearts. Once tails show up, the run is over. It's really simple.

[still_stirrin]

FYI: a LM/VM user’s perspective following …

My combo head is a concentric head with the LM (liquid) collection cup being an annular cup around the central vapor tube that progresses up to a concentric reflux condenser, that is a coaxial water jacket/vapor tube core, just like a liebig condenser. Of note, the condenser is open on top (to the atmosphere), so closing the VM valve and stopping the coolant flow to the RC would result in alcohol vapors venting out of the top, and that is NOT advisable. So, ALWAYS keep your RC cooling whether operating as liquid managed (LM) or vapor managed (VM) reflux.

For some products (depends on the wash/must in the boiler charge), I will start using the LM controls. Because of the liquid cup and the fact that it will always collect some condensate, it is useful to collect the foreshots and early heads in the liquid cup. But after starting and collecting a little of the “frontend”, I will close the LM valve and open the VM valve (a conventional VM with a ball valve) for the rest of the run.

The great thing with VM is that it will hold the reflux ratio constant regardless of the coolant water flow or heat input (vapor production). The VM divides the vapor that splits off to the product condenser and the vapor that returns down the column continuously with the same proportion. So, once set, it keeps the RR constant throughout the run.

What will change through the run is the flow rate of the product at the product condenser outlet. In other words, the output will slow towards the end of the run even as the proof at the spout stays high.

Often, when I get to the end of the run, I’ll switch back to the LM outlet (reopen the LM valve) and close the VM valve and finish collecting. But even as I do this, the proof will fall fast as I pull the last remnants of alcohol from the boiler. This last bit of collection will be mostly “backends” so I save it with the heads for rerunning in an all-feints run.

However, as I noted up front, I don’t always start with the LM reflux controls. Some spirits I start with the VM valve opened slightly and run throughout. I would do this for a spirit that I don’t need the highest proof and keep a little more flavor (a medium RR). As you can see, the VM offers a wide range of reflux ratio settings potential while the LM is good to push the RR up as high as possible. A combination LM/VM head gives you this flexibility depending on what your target spirits are.

I don’t have a cooling managed (CM) reflux head, so I can’t comment on them specifically. Some like them, others struggle with them. But I do like the LM/VM reflux head for high purity spirits. But, a potstill head is still my most-used favorite, as I prefer making whiskey.
ss

[pynys pub]

Thanks there Still Stirrin . All knowledge is welcome . I'm about to be a soon retired millwright at a food facility, so the building part helps play into the hobby. Well when I say soon , within 9 months so just trying to get all my ducks in a row