Cellar Question - dual cooling units

Question for the braintrust. Is anyone running 2 cooling units in their cellar?

I was thinking of expanding my cellar by about 3 x 12 x 7ft (250ish cuft). Right now I am at 600 cu ft. My unit is rated for 650 cu ft, so if I expand up to 1000 cu ft, I would need a larger unit. Instead of buying a larger single unit, I was considering just adding a second smaller unit. Not sure if that would work.

Thought?

Yes, I have 2. In my opinion, wise to have redundancy.

Same here. Ten years ago one failed and the other keept the cellar cool while waiting for a fix.

Never size a system by cubic footage. You would be best served by buying a second system of equal size, giving you some redundancy.

Eric

I have two cooling units, but not for the reasons you state. One (a two piece system) is the primary unit. The other is a backup unit in case the first does not work. Given summers around these parts, I recommend buying a second unit capable of handling your 1000 ft space and use your current unit as a backup.

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How does one ensure they both run approximately equally? Couldn’t one “overpower” the other and essentially keep things cool such that the other never turns on, or does so only rarely?

Absolutely, room configuration and thermostat calibration will affect run times. Most will run a lead/lag set up (ie. unit A=55° setpoint and unit B=57° setpoint) and alternate the settings quarterly or so. With odd shaped rooms they are typically set to the same temperature.

Run time of each individual unit will depend on each thermostats location, ambient temperature and their set point. If there is no physical separation of the room possible or practical, it will be very difficult to find an easy solution to ensure nearly identical run times of both systems since one will ultimately effect the other.

You may want to consider a monthly operating cycle where you set system A to a specific temperature e.g.55F and system B to a slightly higher one, like 56F. The following month you switch the settings and so on. That way you will get comparable run times provided the units are the same capacity.

Reviving this thread. Not many responses, so I’ll assume most fortunate to have wine rooms in their homes don’t have such redudancy in place. How many have experienced cooling uints malfunctioning to the point of damage to their contents?

I’ve had failure, but no damage (and I could see the failure coming - it was having a harder time cooling - so I could plan a bit ahead). But I see you’re in El Paso, where I could imagine damage being more likely. I’m guessing cellars don’t really exist there and of course summer heat could be brutal.

That said, I think the chances are still low even so. First, if your cellar is located in your house and you have A/C you’re likely going to be able to keep the wine at 75 or below, which should prevent damage. Second, the thermal mass of any cellar (at least any with a lot of bottles) is pretty substantial. They don’t just warm up immediately, because liquid doesn’t heat quickly and the surrounding materials, including insulation, help.

What’s your electricity situation - do you get blackouts a lot? You might be better off with a backup generator to ensure constant cooling at least with the central AC if a blackout occurs. A few days at room temps won’t harm anything and should be enough time to get a replacement.

Thanks, Andrew, for your reply. I tend to agree with your assessment. We actually do have basements here, a rarity for Texas. But, the summers are brutal. However, with thermal mass, whole house cooling, etc., I just find it hard to believe that a week (without opening the room, mind you) or whatever to get the unit repaired/replaced is necessary. But, I also have a substantial (for me) investment in that room and while it’s insured, I’d hate to have it damaged.

As an aside, my current house has a back-up generator which has never been needed. We simply do not have natural disasters here and I cannot recall a single outage of any significant duration.

Jeremy, I’m in the Houston area, and we were without power for 8 days due to Hurricane Ike in 2008. I keep my wine room at 55 degrees and the air temp increased about 1 1/2 degrees a day during the outage. As it was getting close to 70, I was talking with a neighbor about borrowing his portable generator to run the cooling unit for a while, but the power was restored before we did that.

While I haven’t experienced it, I have heard/read that one consequence of cooling system failure is the unit can blow uncooled, ambient temperature air into the wine room. If that happens, I’d expect damage to occur fairly quickly, at least if you’re in my environment and blowing 95-100 degree air into the room.

Jeremy, you suck!

I agree with you Jeremy. If the cellar is in an air conditioned space the bigger worry is a prolonged power outage, and a second chiller won’t help with that anyway. That’s where a generator helps. If the cellar is in unconditioned space and ambient temps are really high, two chillers makes sense. Especially if the insulation is not ideal and/or the cellar isn’t that full (lacks thermal mass).

I had two chillers in my old house. Made it convenient if one went out and was reassuring but it was probably a waste of money. The basement the cellar was located in never got above 72 in the summer as long as there was power to run the house AC. We once lost power for 5 days in the dead of summer. Basement got up to 85 within a day but the cellar, which was full and only moderately insulated, went up to only 74.

Yup, living in the high desert has advantages

Very helpful anecdote, David. Many thanks.