GeneC,

Greg here. I did a LOT of investigation when I built my old box back in 2003. As a matter of fact, working in the aerospace/spacecraft trade, I can say don't worry about making all the panels fit perfectly. BUT, make sure to add some type of sealing to prevent air from moving around the edges.

There is also a point of diminishing returns. You can't just keep piling on the insulation and expect better performance.

The main thing I took into account was first convection – make sure the unit is sealed and the air inside can't be exchanged with air outside.

The next was conduction – the insulation takes care of that (R-50 - VERY good).

After that, the radiation – I used Mylar layers with a thin layer of cloth between them. Like the MLI we use in spacecraft. CAUTION – I have seen a number of companies advertising a layer of MLI type stuff for sealing the fridge and claiming a very high R value. It is high, but ONLY for radiant heat!!!

On the other hand, you do need the radiant layer, as can be seen by all the boats in the Sea of Cortez hanging a silver car wind shield cover down the side of there boat just outside the box.

Hope all goes well for you!!

Greg

P.S. Make sure your charge is OK. If your unit has not made I before, and it is making it now, your charge may be getting low. I know it sounds crazy, but I can tell you, they never seem to work so well until just before they go belly up. I won't go into how and how well I KNOW this....