fermentation leaks?

I made this 2'x3.75' fermentation chamber with a small fridge and small heater. Fridge is attached with silicone (I'm positive there are no leaks there. I siliconed it up really good). The heater is inside. In the winter the heater is plugged in. In summer the fridge is plugged in (haven't used the fridge at all yet).

On the inside, at the seams I tried to seal it with that expanding foam. That foam made an incredible mess, and I'm concerned that it didn't even seal the seams. I say this because the outside temp is 60F. The temp inside the chamber, with heater, is 71F but drops to 68F in 45 minutes. So the heater kicks on ever 45 minutes. I'm losing a degree every 15 minutes. Is that enough of a temp loss to conclude that yeah, I have a leak?

I have 2, 5-gallon buckets fermenting in there too.

So I'm thinking about cutting the foam out with a utility knife and filling in the gaps with silicone. I'm confident this will improve the performance.

My concern is once summer gets here. I swear my garage gets to be 100 plus. Maybe as high as 120F with both cars in there. and if that chamber is gonna try to get down to 70F. Man, that fridge will be cranking to maintain 70F.

Any input would be much appreciated. Thanks.

1 degree per 15 minutes doesn't sound like a lot. But...does your chamber have an insulated floor?

Cheers!

Yeah, insulated on all sides with that 1.5" foam lined with that aluminum foil material.

Floor, ceiling, and all sides are insulated.

I wish I didn't use that expanding foam and went the silicone route. But I'm learning I suppose.