I have been adding space in my kitchen redesign for a 24" undercounter wine cooler. It is easy to find models that either have a single temperature and more space (e.g. the Vinotemp VT 52-SN, or some with dual zone and slightly less space (e.g. the VT 45R), though I suspect in the case of my examples most of the lost space is lost to the "display shelf."

Is any single enclosure to be effective (and if possible efficient) at keeping the top and bottom of the cooler at different temperatures? It seems to me that this is not very probable, but what do I know? We're only talking a few degrees of difference here, and actually red and white could happily be stored together at 50 F. But if those are effective, then it might be nice to keep each kind of wine closer to its serving temperature, since the wine cooler will be used just for that (and my crawl space, which is single temperature of course, for long term storage).

Opinions or experiences?

YA

We keep the white zone (16-bottle upper section) at 41 degrees F and the red zone (30-bottle lower section) at 63 degrees F -- so quite a few degrees difference.

We have had it for 6-7 years now and can't imagine being without it.

Are the bottles actually at those temperatures (obviously I am no fridge engineer)? Have you tested the contents at some point? (I look your cooler: nicely streamlined.)

Also... I've always wondered why the lowest temps go on top (seen in displays etc.) when cold air is denser than hot and will want to go down. Maybe part of the whole refrigeration loop?

YA

FYI, the two compartment can be set to any temperature within the range. You aren't obligated to put the lower temp wines (the whites) on top.

I can't actually get at the fridge at the moment (we're mid way through our kitchen reno and the wine fridge, alas, is being stored in the back of our sewing room). However, I'm quite certain the two compartments are completely sealed from each other so the physics of hot air rising/cold air sinking isn't really an issue.

The whole 2 zone thing is actually a trick. Manufacturers use natural air stratification (hot air rising)to say that they have zones. Most manufacturers of under counter units only show the set temperature not the actual temperature in the cabinet.

If you are really concerned with knowing the actual temperature in the cabinet I would go with a Perlick wine storage. Even though they do not have a 'dual zone' unit. They display both the set temperature and actual temperature in the cabinet. The also offer forced air refrigeration which keeps the cabinet within a 1 degree variance of your set temperature. SubZ and Perlick are the only manufacturers that offer forced air refrigeration in an under counter unit to my knowledge.

That's what I thought re: air stratification, but they always show the upper part set at a lower temp than the bottom one, which goes against that.

I called Vinotemp and they told me that the control panel separates two compartments, and that both sides get air at different temperature forced into their compartments. Top is for white (49 to 55 degrees adjustable) and bottom is for red (55 to 65). I could do without the "trophy wines display rack" at the bottom in exchange for more bottles but there's no real way around that.

I've checked the temperature settings on my unit with a thermometer. The settings were right on.

I don't use my unit for long-term storage. I move wine that I'll be drinking in the near term, up from basement storage, and use the wine cooler for convenience.