I ran a charge of vinegar water through a new 2 inch bokakob head with (only) 1 foot of 2 inch reflux column with pot scrubbers in it (1 foot is about all the height I can handle right now, yes I know it's sad
). I ran it on full reflux for an hour, and during that time the temp on the thermometer yo-yo'ed from about 208 and 199 degrees F. It would stay at 208 for a minute, then dip down quickly for 5 seconds or so, then back up to 208. I was thinking that this variance would stop after a while, but it pretty much did that the whole time until I started to take off liquid from it. Then it pegged at 207.8, occasionally dropping to 207.6, once I opened the runoff valve. It stayed there at that temp for 3 hours solid as I ran off about 3.5 quarts of vinegar water. Is this yo-yo'ing of temp expected when doing a full reflux? I'm running on a stovetop hotplate with no dimmer switch, and am wondering if this temp change was due to the on-off cycle of the burner, as it was on a medium setting and I could hear it cycling on and off. Also, will distilled alcohol come off the still faster than the water, as it has a lower boiling point? Will that matter at all? I measured the output of the still at various temps from medium-high all the way up to high (while there was runoff at medium, it was just a few drops every 10 seconds or so-- way too slow for a vinegar washing run). This was on a "large" sized stovetop burner. At medium/medium-high I was able to get 200ml in 18:40. At medium-high I was able to get 200ml in 13:20. At medium-high/high I was able to get 200ml in 9:25. At high I was able to get 200ml in 5:30.
Will these numbers hold to an alcohol run? Are these numbers acceptable (if they're relevant at all)?
My condenser (about 18 feet of 1/4" O.D. copper tubing coiled into about 11 inches worth of condenser) was able to cool all vapors through the whole run. Any time I noticed any steam out the top of the head after raising the heat, I just upped the water flow through the condenser. The output water from the condenser would drop down from warm to cool and no more steam out the top. As a side-note, anyone worried about rolling their own condenser shouldn't. It was really easy-- just wrap around a 1" O.D. steel bar, keeping pressure and tension on the tubing. I'm not mechanically inclined at all and had no problem winding the coil at all, even without a jig. It was practically the easiest thing in the building process. It's not a double-coil or anything fancy, but it obviously handles what my stovetop can throw at it.
The inside of my head and column still look kind of grimy. I ran a bottle brush through it after the run and came out with lots of reddish-black stuff on the bristles, as well as some copper filings and flakes. After seeing that, I'm ready to run another vinegar charge to keep cleaning it out.
One last question, then I'm done (for now). I'm using 1/4 inch O.D. tubing for my takeoff from the head. Is that too thin? I could hear noises in the tube like someone sucking on a straw in an empty soda cup throughout the takeoff part of the run and the output didn't come out in steady drips, more like sputters. Is this ok?
Thanks everyone for the help. None of this would have been possible without this forum.