Wine cabinet humidity problem

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Old 04-27-17, 04:17 PM
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Wine cabinet humidity problem

I'm using a small (8000 btu) LG window A/C to cool a 100 cu' wine cabinet. To keep the bottles at 55F, I have a CoolBot controller which overrides the normal A/C limit of 60F. This works perfectly on the temperature side, however, the humidity has spiked way too high. Desired humidity is 60-70%. Mine is running above 80%. This was really a surprise as I expected the A/C to take humidity out of the air. Humidity above 80% creates the risk/probability of mold in the cabinet, so I must bring it down.

I've tried adjusting the A/C and CoolBot controls testing every possible combination but nothing works. In every case, the temperature is easily controlled, but humidity eventually spikes.

It probably helps to know how the A/C is installed and configured. The unit is a "window" unit and not recommended for through the wall installation, however, that was my only option so I did put it through the wall. It is tilted a bit over an inch front to back and well insulated around the "wall" sides. None of the rear or side venting is covered. The normal front A/C grill was removed so the CoolBot override wires could be connected.

The A/C has a "Dry" mode which supposedly dehumidifies the best. The fan goes on every 3 minutes, the air temperature is checked and if below the set point, the compressor comes on and cools the cabinet down to 55F, them the fan goes off until the next cycle. When in cooling mode, the exposed front fins get wet as expected, but never enough to pool water in the pan or to drip outside. This unit has a "slinger" fan which is supposed to sling water pulled from the fins to the outside air.

Other people are using this sort of A/C CoolBot combination to cool their wine storage area, so I know it's possible. What am I doing wrong? I've considered several possibilities: the cabinet volume is too small for this (8000 BTU) A/C; through the wall installation is somehow interfering with the moisture ejection; the unit is defective.

I've tried using a Damp-Rid tub to absorb moisture, and it does, but not enough to change the high humidity. I might try to exchange the A/C or get a different one entirely or buy a dehumidifier but those are last ditch ideas. Pulling out the A/C and replacing it is a lot of work, so before I do that, I want to make sure I've tried everything else. Any suggestions?
 
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Old 04-27-17, 04:41 PM
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I'm not an expert, however I believe your A/C unit is too large. I suspect that it only runs for short periods of time. To get maximum dehumidification, you want the A/C unit to run for long periods of time. Ideally, the A/C should run almost continuously.
 
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Old 04-27-17, 06:41 PM
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I agree..... it's getting too cold too fast.

One problem area could be because of the slinger method of moisture removal there may be too much water being left inside the unit that is recondensing back into the air.

You need the water to drain out of the unit.
The unit needs to be pitched down outside so that the water drains completely.
A 5k btu model would probably have been better suited for this application.
 
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Old 04-28-17, 05:48 AM
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Air conditioning for computer rooms and data centers has a method of humidity control that works quite well.
When the a/c unit operates in cooling mode it will lower temperature and humidity at the same time.

If the temperature drops to the cut out temperature of the thermostat but the humidity is still high a de-humidistat will take over by keeping the cooling running and energizing an electric strip heater.
This will add heat to the room and allow the air conditioner to continue to run to lower the humidity.

This is not the most efficient set up but there are limitations in equipment sizing in what you are trying to do.
You could experiment by adding a small amount of heat to the room to allow the unit to run longer to lower the humidity and not lower the temperature.
 
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Old 04-28-17, 06:52 AM
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I have an 800 btu chiller working in my wine closet which is about 116 cubic feet. 8'000 btu in an even smaller space is WAAAY too much air conditioner. I feel you will constantly be battling humidity and if you were able to chart the temperatures in your room you'd probably see some big temperature drops with the AC cycles on.

What vapor/humidity barriers do you have in your wine room? Your room may not be sealed well enough and is letting in too much moisture. Even with your monstrously over powered AC it should eventually bring the humidity down if the room is sealed properly. Btu, if too much moisture is able to work in through the walls you'll be fighting a loosing battle.

You can try chemical moisture absorbing and desiccant packs but that too will be a loosing battle if the room is not well sealed against moisture entering. You also may find it helps by having instruments you can monitor from outside the room. If you are constantly opening the door to read a hygrometer you're probably making the problem worse.
 
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