Hi-I have a 1300 bottle cellar built during a basement renovation by a
general contractor. Problem is that temp rises to roughly 62-63 deg
during summer, despite cooler set at 57, which runs almost constantly
(bsmt is airconditioned to around 77 summertime). Once basement cools
off for winter (into high 60's), it cools down to set temp of 57.

Specs--8x6x6 ft, 384 c.f., with Whisperkool 3000 cooler, sized
properly based on cubic footage, all interior walls in air conditioned
basement. Contractor swears insulation was up to spec R13 walls R30
ceiling. Wood door with single (I know that's wrong) pane glass-but I
tried covering the glass with foam insulation board to see if that was
problem but temps stayed up.

I've thought of several possible fixes:
1) Upsize to larger Whisperkool, say 4200 BTU ($1600)
2) Add small second cooler, like the new ChillR units at Wine
Enthusiast, maybe the 1500 or 2000 BTU unit ($500 plus install)
3) Try a double paned glass door despite my experiment ($1000-2000?)
4) Tear up drywall and check insulation ($thousands plus spousal
wrath)

Suggestions? How much bigger a Whisperkool if I did that (is there a
disadvantage to an overly large unit?). Anyone have experience with a
ChillR
unit?

Thanks for your help!