Conditioning a Cellar

[PapaDisco]

I've got a partial cellar of about 600-700 cubic feet. It's dug into the hill with brick or block all around except for a "roof" that serves as the tile patio above. Entrance is from its own exterior door of wood with a glass insert. So all-in-all, pretty subterranean but not completely so.

The space serves as a catch all for my carpentry tools and project bench but it's too small for running saws and stuff, so the environment is pretty undisturbed. I started using it to store my cigar tupperdores in since temperature and humidity are pretty consistent. However humidity does vary over the season and it tends to run on the high side of things (65-80%rH). So I added a dehumidifier just to control the peaks. My cigars are zip locked in their Tuppers with Bovedas, so fine rH is handled by the Bovedas and inside the Tuppers it's a constant 65rH.

The dehumidifier did the job of keeping room humidity at 65%, but at a cost. The machine ads a fair amount of heat back into the room, so now room temperature hovers in the low 70's all of the time. I'm using a HiSense unit with a hose drain, and it doesn't look like there's an easy way to just vent the hot air.

I expect that I'll have to go to a full on wine room conditioner (like a Breezaire or Vinotemp). Most of these seem to have an upper limit of 60F and I'd rather something that was closer to 65F on the upper limit.

I do have an existing opening in the block wall for venting the unit, so that's no problem. I'd just like to keep the cost down and the temperature a bit higher.

Any suggestions or thoughts?

[stogieluver]

No suggestions, but I have a question. Without the dehumidifier, did the tupperdors not maintain the 65% rh?

[PapaDisco]

No suggestions, but I have a question. Without the dehumidifier, did the tupperdors not maintain the 65% rh?

The Tuppers and Bovedas held steady at 65%rH. I haven't had them through a rainy season/winter yet though, when the rH in the room can rise to 80%rH, maybe 85. In the current season, without the dehumidifier running, the cellar would settle in around 75-78%rH and that sort of ambient is easy for good seals, tupers and bovedas to handle (although the bovedas will eventually need a drying cycle). Temperature in the summer in the cellar will be 60-65F with the occasional 2 week blast of 85F days sending the cellar to 70-75F.

I'd say that 40 weeks out of the year the environment is stable, but I need something to knock off the highs and the lows when they come. A whole room conditioner will take care of cooling and dehumidifying, but won't add heat during the bottom of the cold, rainy season in January. Then the cellar will be 55F, so I'll likely have to add some room heat for that, or perhaps just throw a brewer's mat under the cabinet where the Tuppers are stored.

[CUBANO]

There are room air conditioners that have both A/C and Heat.

[PigFish]

Many systems use a standardized 24VAC control. There is no real magic to controlling HVAC, as long as you feed its start relay the correct coil voltage. I would say that you can likely change all or most of it, if you are inclined and have the ability.

There are plenty of packaged HVAC units out there and I don't think I would spring for a dedicated wine cooler unit for two reasons (potentially). These units generally have a pool of water in them (or they can have) as the wine guys like to use that pool of water to attempt to bring some of the condensate, the water that results from cooling the water vapor in the space, back into the space. They are also pricey. I know that you wine guys don't really like a dry space. This pool of water in the cooler idea is what the wine cooler makers use instead of a formal humidifier.

I know what I would do, but I am biased. I would trash all the cooler controls and unify the controls (with one of my own) logic controllers and sensors. I would rig up a relay station that would control the cooling, a small heater, and a humidifier. In this way you have all the axis covered. With a proper controller you can ditch the high rH problem as well and use the cooler as a dehydrator in conjunction with the heating unit. I would not use a heat pump...

In this size of space, you are not going to get precision control, but you should be able to get it pretty stable if you work at it. The nice thing about larger spaces is that they swing more slowly and what you lose in precision you can likely pick up in stability.

If you study the problems and put your mind to it, I would think that you could store cigars in the open in there if you do it right.

Good luck on the project! Cheers... -Piggy

[PapaDisco]

Ah, I was wondering how humidification/dehumidification worked in those Vinotemp machines. Doesn't sound like my preferred solution, other than the convenience of having a controller already connected to a cooler and stuck in a box.

Why would a cooler + heater as humidity control be more efficient than just a small heat pump and a standalone dehumidifier? Low humidity is not a problem in this space, so I definitely don't need a puddle of water sitting in a Vinotemp. Mostly I need cooling 2-4 weeks out of the year, and heating about 2-4 weeks, and then dehumidification.

The goal here is to get the temp/humidity stable within a small range, and then to switch to coolers instead of tuppers and keep the bovedas. Like that, the cooler + cigar cabs add another thermal layer and I suspect that even if the room moved up or down a couple of degrees the cigars themselves wouldn't see that change.

[PigFish]

I am thinking that if you do it properly, you could store cigars in there in boxes. I mean if you want the sub-climate coolers, that is a personal preference, but when you start talking PLC control, which is my gig, I say go for the whole apple!

The problem with a heat pump is that you are using what I call wet space (dehydration) cold space (cooling) and heating off the same unit. I can manage to work both cooling and dehydrating off of the same cooler, but if you have over hydration issues, you would be dependent on refrigeration to dry as well as to heat (reverse cooling) to offset any loss of heat during dehydration. There are likely switching dwell times that would need to play out here as well as short cycle times that add up to this combination not working (that is my guess anyway). Additionally, along with the short cycle problems, you will be bringing tons of water from the wet space (the cooler) back into the formal humidor during heat. This has got the earmarks of a nightmare to me. Frankly, I don't think you can pull it off. It all depends on how the heat pump/fan coil system is designed.

I use a concept of a shared system for cooling and dehydration and it works well in my sized projects. I cannot see why it won't work here; you will just have some negative preconditioning (wetting) during cycles that I don't think you will be able to get rid of unless you tear open your room air-conditioner and perform some relay timing work on your own (not that it is out of the question). Otherwise It should work pretty sweet as long as you understand (and I am theorizing now) that you will lose some precision on one hand for long wave stability on the other. In other words you will likely see some variations away from a set point to make the system work and not bounce off set points, but due to the size of the space, I would think that overall it should be pretty stable. I would think that you could get long wave periods of perhaps 3 rH and 3F without a lot of set point bounce. With some work you might even be able to whittle that down some. Certainly even at that, you will likely have cigars better kept than a large percentage of typical cigar smokers.

Anyway, that is how I would do it...

Cheers -R

[PapaDisco]

Been thinking about those switch/dwell time issues you mentioned Ray. I guess it depends largely on how quickly the liquid water can be removed from the system yes? So the cold plate pulls water from the air, condenses it into liquid, and then pumps it down a drain. As soon as that water is gone the heat cycle (if needed) can start.

Such a combination of cooling/heating/dehydrating wouldn't work with the Vinotemp style machines, because as you point out, those hold a pool of water within them for hydration, but with a heat pump that's connected to a drain we should have a pretty successful, full space conditioning unit.

Now aiming for your standard of homeostatic perfection would most likely require better controllers for the heat pump? I'm guessing the standard unit from Walmart is going to be slumming it with something pretty basic and unreliable out of Shenzen.

Since my space is a bit multi-purpose, I'm going to have to keep with Cooler/Tupperdores anyway and so those will confer the final level of environmental consistency on my sticks. If I can get the heating/cooling within the room to hold steady over the year within +/- 2-3F I think that will work for now.

I also like the idea of storage that is somewhat "fail-safe." So if the electronics in the system fail, the cigars are in a space that isn't going to go to 90F or get soggy.