Humidity/leakage from keg box

[SCREDMON]

Finished my keg box in late fall, when humidity levels were falling in SouthEastern PA. Now the plywood underneath one of the doors is wet and getting some mold, so I know I have to do something. Not exactly sure what’s going on, but I have a theory:

A little more explanation first. I extended the size of the keg box to 66 inches long, insulated with the 2″ green extruded foam insulation (doubled up where I had the space – like on the sides, bottom and top) and then lined the whole inside with FRP board with silicone caulk corners to make the inside pretty waterproof. So, I don’t think the moisture from inside the fridge is getting out through any sort of crack or holes. I took apart an old mini-fridge and also mounted a computer fan in the cooling unit to cool everything down. I have two doors from two old mini-fridges. One of them (#1) I couldn’t get to shut flat, so I put some weather stripping and a latch to really shut it tight. That one doesn’t seem to have any wetness around it. The other (#2) was perfectly flat, so I put metal corner bead around the plywood opening to the keg box and the magnetic seal on the fridge door seals against the metal corner bead really nicely. When I stick my head in through the door opening #1, I can’t see any light through the cracks when door #2 is shut.

My theory is that since the metal corner bead spans from inside the fridge to outside the seal from door #2, it is getting cold, then where it is exposed to the outside, it is sweating and dripping down onto the plywood. Does that seem plausible or has anyone else had a similar issue? I really like the fact that this door opens and closes without any hinges or latches, but obviously it can’t be sweating and “leaking” all summer long. I want to get this fixed within the week so I don’t do any lasting damage or cause mold growth that I can’t fix with a little surface bleach action.

Any ideas or similar experiences would be appreciated.

Thanks

[SCREDMON]

resealed both doors a while ago and also turned the fridge temp up to 45, about as warm as I’d want to drink beer and thought I had the problem solved. Turns out I had also turned the air conditioning in the house down, which was driving humidity out of the basement. Today I took the keg box apart and had a TON of moisture in the plywood under the floor of the bar, underneath the insulation.

It is drying now with a box fan and a few days of patiently waiting. Now what? Any suggestions?

I did realize that I had only used a total of 2″ of insulation, R-value of 9.5. The plans call for the floor to be double insulated with R-7.5, so maybe that is my mistake. Once I get everything dried out, I’m going back at it with another layer of R-6.2 1″ foil-lined insulation on top of what I had in there, then I’m going to re-seal everything back up and hope that solves the problem. Since I didn’t have this problem in the winter, I have to believe that the issue is the condensation from the humidity on the back side of one of my panels somewhere.

Any other thoughts?

[bartender_adm]

it definitely sounds like condensation.
Is the freezer plate frosted up too?
Does your fridge have a defrost cycle?

Regarding the floor – You should have the double insulated floor layer, then 3/4″ treated plywood floor panel, then cover that with thin aluminum sheet.

The only time I see water is if the fridge ran for 6 months or so, then shut down for a few hours…as the freezer plate frost melts.

[SCREDMON]

Ugh, 6 months later and after tearing out the entire keg box, the condensation returns. I’m not seeing mold anywhere (yet), but there was a huge puddle, probably 8-12 oz of water in the back of the fridge. When I reinsulated, I used 2 layers of 2″ foil-backed insulation, plus another layer of 1″ insulation for a total R-value of 23 on the floorboards, then plywood, then aluminum sheet. I also added 1″ insulation to the ceiling and walls. sealed everything up with Great-Stuff foam so I feel it’s really tight.

The only difference for my project is that I have two mini-fridge doors that I use as access. They still have the rubber door gaskets on them, and they seal against rubber foam weather stripping that I installed, and close with window latches that pull the doors really tight. When the doors are closed and latched, there is zero light getting through…but what are the chances that humid air is getting in somehow? Its the only thing I can think of.

The cooling coils get droplets of ice on them, but no frost builds up. And I have the compressor/condensor outside the fridge and controlled by an external digital thermostat controller. If there is a defrost cycle on my fridge, how would I know and how can I disable it?

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