Dehumidifier advice for actively cooled cellar

Hi, I have a 25m3 wine cellar that is cooled by an Inoa 50 through wall cooling unit from Eurocave.

I am monitoring relative humidity with a datalogger and I see excursions over 70% RH for most of the summer months. This summer we have had a very wet spring and I’ve seen mildew and mold establish itself on my racking.

I have two questions.

I see dehumidifiers exist in compressor or dessicant models. Which model would be best for a wine cellar maintained at 14C?

Would people advise I place the dehumidifier in the wine cellar (where either type would act as a heat source), or outside of the wine cellar in the room where the Inoa 50 is located, and drawing air from?

I want to get the humidity down from its current 76-88% to around 60% quite quickly and get the mold/mildew killed which is why I want to get a dehumidifier involved sooner rather than later. I will also call Eurocave and ask them to check the unit (it was just serviced two months ago) as the Inoa units are supposed to maintain a correct level of humidity as they cool.

All advice gratefully received.

Dave M

Wow. Where is that high of humidity coming from? What is the humidity like in the surrounding rooms? What type of flooring does the cellar have? The cooling units in our wine room and wine storage remove humidity to a point we may have to add a humidifier.

Not what you asked for but lower fan speed removes more humidity. And no products with chlorine to remove mold and mildew.

Thanks Michael and Randy.

The rooms surrounding the cellar are currently at 23C with 60% RH. This morning the cellar temp is 13C with 73% RH. The floor is made of bamboo, on top of a concrete slab with a 3mm foil backed underlay. There is a sink in the cellar that is rarely used and I am quite positive the source of the humidity is not a leak in a pipe etc. - it’s simply the fact that the high relative humidity in the room in which the cellar conditioner is drawing it’s air means that the dehumidification capacity of the cellar conditioner is being surpassed as it cools the air from 23C to 13C.

I’m currently leaning towards installing a compressor type dehumidifier in the room in which the cellar conditioner is installed in an effort to drive down the humidity in that room. A compressor type dehumidifier makes sense in that situation, since the ambient air temperature is well over 15C.

Michael I take your point about the fan speed/air flow and can discuss that with the folks from Eurocave. Also I was aware of the advice not to use chlorine based methods to kill existing mold/mildew. On that note what should one use to kill mold/mildew that is established within a cellar? My racks are also built of bamboo - a bamboo plywood that has been treated prior to installation with one or two coats of a water based varnish.


FWIW, I’ve had summer humidity problems as well in my cellar. Cooling doesn’t seem to run enough to keep it below 70%. Similar sized cellar (about 700 sq. ft ~ 20m3)

I put in a dehumidifier (the standard type you can get at big stores) and tweaked the setting to keep the humidity generally below 70%. It’s worked fine, and while it puts out some heat, it doesn’t seem to run so much that it overwhelms the cooling system.

Is your cellar insulated correctly with vapor barrier?

Thanks all. Leo, yes it is insulated with about 20 cm of polyurethane in the roof and 10 cm on the walls. The polyurethane is backed by aluminum on either side of the boards and all joints are aluminum sealed so a vapor barrier is established.

One ‘gotcha’ that I have realized today is I built my shelving out of bamboo plywood which I am beginning to realize may have been a big mistake. I have seen several suggestions that this is one of the less mold resistant wood choices I could have made…eesh.

In any event, I have ordered a compressor style dehumidifier today which I will install in the room adjoining the wine cellar in an effort to get the RH in that space down to about 40% or so. At that point I will see what RH drops to in the wine cellar proper.

I will look at sanding the racks in situ (I built them to not be taken apart), treating with some non chlorine based fungicidal treatment, and then finishing with some heavy duty varnish (non solvent based or low volatiles) with a fungicide incorporated. I am hoping that can do the job and that the mainstay of treatment will be getting the RH in the cellar down to about 60%.

Still keen to hear any comments/suggestions but thanks all.


An active cooling unit should remove all the humidity in a cellar that has a properly installed vapor barrier. The fact yours doesn’t strongly suggests you have a big problem with your barrier. IMHO first place to check would be ceiling and floor.

Other than mold issues, whats the big deal about high humidity? Shouldnt have any detrimental impact on the wine.

For one, it ruins the appearance of many of your labels, unless you shrink wrap all of them before you put them in. And sure, it’s just the outside of the bottle, but it is kind of a downer to have your great old bottles look like crap.

low-mid 70s % rh is fine. it won’t do anything to your labels. it will likely decrease in the winter months.

I thought the takeaway from the new Somm movie was that mold is a cellar’s best friend. That DRC cellar looked pretty pristine however.

Thanks all. Quite positive the vapour barrier is not the issue - both because I did the installation and seam sealing myself and because I’ve since learned that the Inoa unit recirculates the same air rather than cooling new air, so once humidity starts drifting up in a well sealed and well insulated cellar it tends to continue to do so.

Also agree here that from the wine storage perspective humidity in the 70-88% range is fine, but I only want enough humidity to ensure corks do not dry out. As is, the bottles are lying on a 10 degree slant from horizontal so the interior part of the cork is in contact with wine and if I keep humidity in the 60-65% region I do not believe the corks will suffer. At that lower level I should expect far less mold growth as well.

I have used a vacuum cleaner and fine steel wool to remove the mold on about half of the racking surfaces that were affected. The dehumidifier should arrive today or tomorrow so I will get that installed. I am currently researching fungicidal treatments and fungicidal wood sealants. I want to find a wipe on fungicide that will not create any volatile compounds that I would need to worry may taint my wine. Similar challenge for the fungicidal wood sealant although I also need something that will permit application at 13C.

Any suggestions on wipe on fungicides or fungicidal wood sealants that can be applied over an existing (water based) varnish gratefully received.


All cooling units cool cellar air as it recirculates thru the cooling coil. None that I know of introduce new air. As the recirculating air passes thru the cooling coil it is cooled down by approx 10°F. So if you are maintaining a cellar temp of 55°F, the temp of the air leaving the cooling unit should be about 45°F. This temp is well below the dew point of humid air at 55°F and the excess water should condense on the cooling unit coil and then exit the unit via the condensate drain.

Maybe you should check the temp of the air discharging from your cooling unit, and if that looks good, check to see if the condensate drain is plugged up or is maybe draining back into your cellar…

I assume there is no practical way to put a dehumidifier unit into a wine cabinet (as opposed to a walk-in cellar), right? They have to be plugged in, for one.

I have three cabinets, and one just has ridiculously high humidity, makes many of the bottles look like crap unless I shrink wrap them.

I knew someone who used hairspray to protect his labels.

I just ordered a $35 mini dehumidifier on Amazon for my small actively cooled storage space.
Units this size are advertised for keeping closets dry.
My storage isn’t airtight so I got a thermoelectric unit which plugs in to a wall outlet.
The 14 oz catch tank will need to be emptied occasionally.

You can buy a desiccant based mini dehumidifier for even less $ which could be used in a wine cabinet.
The desiccant needs to be recharged occasionally, by baking I suppose.