You can feed the supply in from the top and still have as much control as feeding from the bottom, you just need to put your control valve at the exit of the last tube at the return line and the water will back up and fill the tubes and the cooler water is at the top of the column. I haven't tried it yet as I don't have my still order yet but that is what I'm thinking of doing... Just my thoughts, what do you think?
Captinjack

That would work too, but I would be concerned with leaks. In my model, the only line which is pressurized is the line from the pump to the valve. Two potential fittings to leak due to the pressure.

For my column, if I went the other way, I would have pump to top of column, then two hoses feeding the various pipes at the top of the column, then the outbound line to the valve, so 8 potential fittings to leak due to the pressure.

Maybe that's not a problem for folks, but my PS II unit had a problem with leaks even on non-pressurized lines until I replaced some of the hose clamps.

i have your setup duplicated and will try it when i finally get back to a mash. i run it from one pump with two valves--still fooling with the radiator
which i dont think will be adequite.

i'm trying to get a picture in my mind of the diferent effect of feeding diferent directions from the top

i'm trying to get a picture in my mind of the diferent effect of feeding diferent directions from the top

scotty,


It's that thermo class again ... coming back to haunt us!:)

Think of it this way: it's purely a matter of efficiency. The larger the temperature differential between the two fluids (the vapor and the cooling water), the more efficient the heat exchange will be. Counter-flow just does a better job at maintaining that temperature differential over the length of the condenser -- the lower latent heat at the top meets the cooler water, and the higher latent heat at the bottom meets the warmer water. So counter-flow gives you a higher average differential. Since it's just a matter of efficiency, the question becomes: do you really need the increased efficiency or not? I barely have a trickle running through my column condenser, so in my case I'd be surprised if I would really be able to notice a difference.


md: I know what you're saying about LM vs. VM vs. CM and power management. The heat/power management (HM/PM) concept applied to a reflux rig still bothers me. I know it's a generally accepted thing, but I think it's a bit of a square peg in a round hole ... and it doesn't really describe anything different. This is what I mean: if you take an LM, VM or CM rig and put it in full reflux, the dynamics are practically identical (vapor rising and liquid falling creating a heat exchange in a closed system). The difference between them (typical construction techniques aside) is how the reflux ratio is controlled. LM removes liquid, VM/CM remove vapor. So I've always considered CM rig to be a special case of a VM ... the column condenser is basically performing the same function as a valve in a VM. And the amount of power applied doesn't have any bearing on the technique used to modify the reflux ratio (whether you're removing liquid or vapor) -- it only affects the volume of the potential reflux in a given amount of time. And I can adjust the power on any type of rig. So it's never been clear to me how or why HM/PM fits into its own category.

Anyway ... just some rambling thoughts on this sleepless evening.:) I'd love to have a long conversation with a thermo expert one of these days to see if I could understand things better. I'm still brooding over my lack of effort/interest (and wasted opportunity) many years ago in thermo class!

--JB