DIY immersion chiller - inlet water goes to the bottom?

Hi folks,

I'm in the middle of building an immersion chiller. I'm about to solder on the garden hose inlet and outlet connections.

There is a choice to be made about the inlet for the cold water. Would it be best for the cold cooling water to go down the vertical part of the tubing to the bottom of the coil (and then wind its way through the coil and out) or vice versa?

Any opinion, preferably with some sort of scientific theory, would be most appreciated.

Cheers!

mine starts at the top(heat rises) and works its way down. but as lons as the water it running i dont think it will matter much.

I've heard two (very heated) arguements for either way.

There's the whole thermodynamics heat at the top-cold-against-the-heat theory that makes sense to me.

However, I've always done water in the bottom. The reason being that if there is air in the tubing, as you throttle back the water flow the bubbles will not get pushed out; forming dead spots on your chiller surface. You only need to slowly flow water down a vinyl tube to see this effect.

Pushing water from the bottom may not be as thermodynamically efficient, however, it pushes the air out the tube making sure there are no dead spaces in the chiller.

I don't know of a controlled experiment either way.

Buzzkill and Derrin,

Thanks for the input.

My way of thinking (apparently incorrect, ha!) is that if the cold water entered at the top (where the hottest wort is) it would then, in effect, be heating up the rest of the wort as it progressed down the coil. If, on the other hand, it entered at the bottom, it would still have capacity to absorb heat from the hottest part of the wort as it progressed to the top to the exit.

This choice happily coincides with Derrins point about air pockets so that is the way "ll go.

Cheers!

I asked my son the Chemical Engineer...he said it's an incalcuable difference.

I have found the inflow/outflow direction makes little difference. The thing that makes a huge difference is swirling it around. If you let it sit in one place it's much less effective than if you stir the pot with the coil.

Those of us in Florida have warm tap water to begin with...so I've made an adapter for my Jockey Box.

[img=http://img35.imageshack.us/img35/1831/dsc0006plu.th.jpg]


One adapter hooks up to the front of the Jockey Box...the other to the rear...and from there to my immersion coil. Fill it with ice/water and let the temp of the wort fall much more rapidly.

Almost forgot...

When you put a coil in a Jockey Box...the same question arises.

I built mine wrong...I come to find out.

The best way for the Jockey Box is for the Beer to come in and go right to the bottom...and spiral it's way up and out. It's not a question of which way cools best...it's which way is easier to get the residual water out of the coil after flushing.

I've got a hose adapter that hooks to the back of the box...and flushes the coil with fresh water. Then I hook up the CO2 tank and blow the water out. It would do a better job if I had hooked up the coil the way I mentioned above...cause you can turn the jockey box upside down and blow all the water out with the help of gravity, sprialing down the tubing.

Just a thought...

If you're relying on temperature gradients to gain efficiency, it means you're not moving the wort enough. You should be agitating the wort by moving the chiller around or stirring the hell out of it with a spoon.