Condenser water flow

[Grandvewe]

Hey Gang.
I have a FSD SS pot still.
I have set it up with the cold water entering the top of the Product condenser flowing downwards.
I also have a needle valve at the top before the water enters to control flow.

I have recently read that it may be more effective to have the water flowing in from the bottom of the condenser and the water flow going upwards.
And to also have the needle valve at the bottom.

Can anyone clear this up for me as to the best method?
:text-thankyoublue:

[JayD]

I have always introduced the condensor water from the bottom of the condensor... :handgestures-thumbupleft:

[Canadoz]

General consensus is to have it counterflow the direction of vapor flow. As you've put it, this is bottom to top.

The reasoning I've read behind this is that it allows the coldest part of the condenser to be at the exiting end, allowing the vapor to condense gradually as it flows down the condenser.
If you have a particularly efficient condenser for the size and flow volume of your still, running the coolant water the opposite direction (top to bottom) can cause the vapor in the condenser to collapse suddenly causing "huffing." You will literally hear your still softly chugging like a steam engine if this happens. This is considered a bad thing since it can create a suction, defeating the natural flow of vapor and leading to significant blurring of your cuts.

I'm no expert, but that's what I've read.
:geek:

[Grandvewe]

Thanks JayD and Canadoz!

You have saved me some potential issues :handgestures-thumbupleft:

[Grandvewe]

And any better spot to put the needle valve to control water flow? Before entering condenser or after?

[Canadoz]

And any better spot to put the needle valve to control water flow? Before entering condenser or after?

I always put it before, Though it may work just as well after, the important part is the direction of water flow, I can't see the valve placement causing any issues.

[db1979]

Do you even need a needle valve on your coolant lines of a pot still? Aren't you trying to condense everything and therefore want maximum flow?

[Jonno]

Your right mate, pot still dont need a needle valve. Maybe if your trying to limit the amount of water your using from a tap maybe?

Just pump as much water as you can threw her and she'll be fine :handgestures-thumbupleft:

[Yummyrum]

Agree .Needle valve would restrict water flow too much . I have just a normal ball valve on my inlet because my hose is quite some distance away.

I like to be able to adjust water where I can see whats happening .Being on tank water,I'm a bit careful

[Grandvewe]

Ah I have been reading so much lately about bubble reflux stills that im confusing info.
I assumed because a dephlegmator needs water flow control that the product condenser does too.

Thanks for clearing that up guys.

[NotBenStiller]

The reasoning I've read behind this is that it allows the coldest part of the condenser to be at the exiting end, allowing the vapor to condense gradually as it flows down the condenser.

Sounds reasonable.
I think they originally set it up this way because way back when, condensers were used in 18th and 19th century lab experiments and they probably made their condensers out of glass - this set up would have stopped them cracking from thermal shock.