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Hi there.

I too much of novice to fully follow the excellent threads on this forum. I think I need some help, maybe a dumb question.

I am expecting a Dephlegmator being delivered in a couple of weeks. Now, I've been reading a number of posts on the forum where the discussion circles around power vs the flow of cooling water flowing through the dephlegmator, and how this is used to "dial in" the outtake speed and ABV. However, these posts also speaks of changes to Dephlegmator temp, and this throws me.

When I have read about changing dephleg temps, I have always thought of it as temperature changes of the water going out of the dephlegmator as a consequence of the increase or decrease of the cooling water flow. I have been under the impression that the dephlegmator cooling water going in was constant, or as near constant as possible - is this incorrect? Are we also changing the temperature of the cooling water going into the dephleg in order to control the outtake?

If the temperature of the cooling water for the dephlegmator is variable, what temp should I start with? Is there a guideline where to start?

Firstly people need to know what type of still you will be using this deflegmator on.
Deflegs are usually used on plated or capped column stills.
Knowing the still type will help members help you.

PalCabral wrote: ↑Sat Dec 21, 2024 2:49 pm If the temperature of the cooling water for the dephlegmator is variable, what temp should I start with? Is there a guideline where to start?

I will try to answer this part.
If using a plated or capped column you firstly need to find a power setting that is not overwhelming/ flooding the plates.
You do this with full water flow to the deflegmator/ full reflux.
Once you have achieved that you slowly reduce water flow to achieve the desired product output speed. This is best achieved using a needle valve. Other types of taps don't allow fine enough adjustment.
Your over thinking the water temp thing, regardless of water temp it takes as much water flow as it takes to get your desired product off take speed.
I've never run a thermometer on a deflegmator and don't see a reason to.

Having a source of cooling water that's at a constant temp and pressure makes adjusting the "flow" through the dephleg easier and more accurate. The temp of the waste water doesn't matter, it is what it is.
When only a trickle of water is going through the dephleg the water will be almost the same as vapor temp.
If the flow is wide open there's lots more flow but the water will be at a lower temp.

Saltbush Bill wrote: ↑Sat Dec 21, 2024 3:37 pm
Your over thinking the water temp thing, regardless of water temp it takes as much water flow as it takes to get your desired product off take speed.

Saltbush Bill wrote: ↑Sat Dec 21, 2024 3:37 pm Firstly people need to know what type of still you will be using this deflegmator on.

Of course, I actually started my post with a background but then cut it out to keep it short. Sorry. I will be using a modular CM column still of 2” pipes. When I use the dephlegmator it will be the last column module before the vapors are taken off to the pc. The rest of the column below the dephleg will be packed with copper mesh and SPS. No plates yet. When the dephleg is mounted, the column will be max 97cm/38” tall.

Thanks for your answer and description of how you do it. I was overthinking it (again). I am planning to use a valve to control the flow of coolant going thru the dephlegmator, using a separate hose system, independent from the pc’s cooling water.

I was planning to follow the MO you described, finding the 100% reflux first and then using power vs rc flow to find the desired outtake of flow and ABV coming out of the pc.

Thanks for putting me ”straight” again! Appreciated!

shadylane wrote: ↑Sat Dec 21, 2024 3:48 pm Having a source of cooling water that's at a constant temp and pressure makes adjusting the "flow" through the dephleg easier and more accurate. The temp of the waste water doesn't matter, it is what it is.
When only a trickle of water is going through the dephleg the water will be almost the same as vapor temp.
If the flow is wide open there's lots more flow but the water will be at a lower temp.

Thanks for your answer, Shady. I am reassured to say I was overthinking it. Your descrpition was like I had thought it would be, but then I threw in a third component of variables by adding cooling water temp and panicked. Thanks!

PalCabral wrote: ↑Sun Dec 22, 2024 2:05 am

shadylane wrote: ↑Sat Dec 21, 2024 3:48 pm Having a source of cooling water that's at a constant temp and pressure makes adjusting the "flow" through the dephleg easier and more accurate. The temp of the waste water doesn't matter, it is what it is.
When only a trickle of water is going through the dephleg the water will be almost the same as vapor temp.
If the flow is wide open there's lots more flow but the water will be at a lower temp.

Thanks for your answer, Shady. I am reassured to say I was overthinking it. Your descrpition was like I had thought it would be, but then I threw in a third component of variables by adding cooling water temp and panicked. Thanks!

I don’t think you are overthinking it but rather you are aware that yes , variations in input coolant temp and pressure will effect the product output rate .

The question is how much these variables change .
Coolant supply temp from a domestic water tap will be fairly constant but the pressure is likely to vary up and down as toilets are flushed or washing machines do their thing .

If you have a tank of water to use , then the temp will slowly go up throughout the run , but the pressure will usually remain constant due to the pump you are using .

Big tanks will heat up slowly and require minimal adjustment of coolant flow throughout the run . Small tanks will heat up quickly and you will be adjusting that coolant flow constantly










You could look at a VM head
Very immune to variations in coolant temp , coolant flow and power fluctuations

Yummyrum wrote: ↑Sun Dec 22, 2024 2:50 am The question is how much these variables change .
Coolant supply temp from a domestic water tap will be fairly constant but the pressure is likely to vary up and down as toilets are flushed or washing machines do their thing .

If you have a tank of water to use , then the temp will slowly go up throughout the run , but the pressure will usually remain constant due to the pump you are using .

Big tanks will heat up slowly and require minimal adjustment of coolant flow throughout the run . Small tanks will heat up quickly and you will be adjusting that coolant flow constantly

Very good points of input. I am lucky to live in a place with solid cold water supply but there will be slight fluctuations both in terms of pressure and temp. I will be connecting the dephleg to the the tap water directly and controlling the flow with a valve. Setting it at cold will ensure a pretty much an even temp and the valve should ensure the flow.

The pc will be connected to a tank, with a pump pushing the water in the closed system. Still have to figure out a smart way to replace the water once it gets hot.

I have a question related to temps. I was given a real nice 26 gallon still setup and with it came a fan converted to a cooling system that sits on a 55 gallon barrel with a water pump and circulate cooling the water. With my setup I have always used my well water that has a constant temperature. Collecting my well water in a garbage can then when it’s not too hot watering the garden. I am guessing the fan cooling system works but if it’s a long run it will eventually change the water temp creating adjustments.
Not trying to derail this thread.

That's the thing Bushy.
Soon as hot water starts to contaminate your cool reservoir water you'll look forward to increasing flow rates.

Here is a solution to help minimize flow rates. Though the pump should have been placed at the lowest position.