reflux temp

[Daveweldz]

I spent this evening reworking my boiler/still. Biggest addition was a thermometer to the out going reflux column vapor stream. Couple questions.
I ran a watered down cheap bottle of Vodka thur to clean the various joints and fittings. what else should I do, vinegar??
I have a temp gauge on the boiler, when running the pot still this was the bible for me. When running the reflux is it fair to say that the vapor temp at the top of the reflux is the bible?
My boiler will run 20 to 30 F higher then the reflux temp. Hope this is normal. I asume the nastys being vaporized at these higher temps are caught in the reflux action?
So what is happening at the top of the column is what determines what will come thur the condenser and dont pay too much attention to the boiler temp? for cuts etc....????

Thanks Dave

[Hawke]

Yes, for a reflux, the temp at the top is what you watch. Once the column has equalized, there can be a 20*C difference between the pot and the top. Let it run at 100% reflux for at least a 1/2 hour before you start taking any product. The temp should be close to 78*C (172.4*F)

[CletusDwight]

II have a temp gauge on the boiler, when running the pot still this was the bible for me. When running the reflux is it fair to say that the vapor temp at the top of the reflux is the bible?

That's an interesting question. I originally built a reflux still and I ran it that way, using the vapour temperature as a guide.
But then I stripped it back to a potstill to get flavour.
I continue to watch the vapour temperature at the condenser input. Seems to me it makes more sense as a measure of abv in the distillate. I have no idea what the boiler temp is. Could be several degrees hotter.

Don't mean to hijack the thread, but anybody tell me any reason why I should measure it?

[plonker]

Hi Daveweldz,
I dont find temp or %abv to be useful when running my VM reflux. It runs at 95-96% almost all of the run and around 75 C for most of the run. But the smell and taste will change dramatically throughout. The cuts seem to be much clearer and sharper with a reflux

Im running off some rum feints at the moment, and have had almost 450ml foreshots, 500ml heads, and Im up to 2L of hearts and still going... temp has changed maybe 2-3C %abv has not changed at all. I dilute to 40% in a little shot glass and taste..

Hope this helps..

[rad14701]

While the temperature at the top of the column is the only temperature that is important, you can't regulate your heat input based on this temperature... Reason being, if you were to attempt to regulate heat input based on the vapor temperature then the boiler won't push enough vapor for adequate reflux for take off rate at purity...

The boiler should be producing more vapor than needed to maintain proper temperature at the take off rate at which you are collecting... In return, the added reflux will help keep the temperature and purity stable... Running just at the edge turns you into a still jockey, constantly making small adjustments throughout the run... Also, without adequate reflux it is possible to maintain vapor temperature while the purity gradually decreases - similar to a pot still except without the temperature change...

[MuleKicker]

I run 2 RTD temp sensors in my LM. i use the keg temp only because that temp gives me a good idea how much alcohol is left. I have a RTD temp probe in the top of the collumn right before the condenser, it goes to a digital dislplay that reads .1C. when running I can run that temp right at 78.3C, and it stays there until my keg temp reaches about 93C, then i have to start fiddlin with the reflux valve. so when doing a spirit run, keg temp settles at 81-82C until i have taken 2-3 litres, then it slowy starts to climb as i take off. the thing will pretty much run itself until the 93 mark. (and providing i use a big enough capture vessel )