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A finished stone wine cellar with wooden racks of unlabeled bottles, a flush supply grille and return grille of a ducted cooling unit set into the upper wall, and through an open doorway the plain mechanical room beside it.

Choosing and comparing

Through-the-wall, ducted or split: where the cellar's heat should go

The types of wine cellar cooling systems differ mainly in where the heat goes. A through-the-wall unit exhausts into the room behind the cellar, a ducted unit sits in a nearby space and moves air through insulated ducts, and a split system puts the compressor outdoors or in a distant room, joined to the cellar by a refrigerant line set.

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  • Which system suits the room, and keep or replace
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At a
glance.

Every cellar cooling unit does the same job, pulling heat out of a sealed room and dumping it somewhere else. What separates them is where that somewhere is, how much of the machine you hear, and how the room was framed around it.

Read the whole guide

Simplest to installSelf-contained through-the-wall unit

One opening, one plug, but the room behind it takes all the heat.

Quietest inside the cellarSplit system or ducted unit

Only a fan coil or a pair of grilles sits in the cellar itself.

Needs a refrigerant technician to installSplit system

The line set is brazed or flared, pressure-tested and evacuated on site.

The deciding questionWhere can the exhaust heat go?

A closet or a small utility room rules out more options than any budget does.

Four layouts that do one job

Inside every one of these machines is the same loop: an evaporator coil that runs cold and a condenser coil that runs hot, with a compressor pushing refrigerant between them. The layouts differ only in how far apart those two coils sit and what connects them. That distance decides the noise in the cellar, the work needed to put the system in and who can service it later.

Owners often compare the types of wine cellar cooling systems by capacity first. Capacity matters, and a separate guide deals with it, but a unit of the right size in the wrong layout still fails the room: the heat it removes has to land in a space that can absorb it.

  • Through-the-wall: one box set into an opening in a cellar wall, cold face in the cellar, hot face in the adjoining room.
  • Ducted self-contained: one box in a mechanical room, attic or next-door space, with insulated ducts carrying cellar air to it and back.
  • Split: a fan coil inside or near the cellar and a separate condensing unit outdoors or in a ventilated room, joined by copper refrigerant lines.
  • Ceiling-mounted: usually the in-cellar half of a split, a flush evaporator in the ceiling with its own condensate pump.

Through-the-wall in practice

This is the layout most small cellars start with. CellarPro's 1800 series, for example, goes into a hole cut a quarter inch larger than the unit, needs a dedicated 15-amp circuit and at least 8 inches of clear space in front and behind. The trade-off is that the compressor lives in the cellar wall, so its hum and fan noise reach the bottles and whoever is standing among them.

Ducted units in practice

A ducted unit moves the whole machine out of sight and leaves a supply and a return grille in the cellar. Wine Guardian recommends keeping the combined supply and return duct length, bends included, to about 25 feet, and asks for insulated ductwork so the cold air does not sweat or pick up heat on the way.

Split systems in practice

A split system is the only layout that can send the heat outdoors without a long duct. WhisperKool's ceiling-mount split, for instance, is rated to hold 55°F in the cellar while its condensing unit sits in air up to 120°F, and it asks for separate dedicated circuits for the evaporator and the condensing unit.

The room that receives the heat

A self-contained through-the-wall unit is only as good as the room at its back. CellarPro asks that the space behind the unit be at least as large as the cellar itself unless its intake and exhaust are ducted, and it rates the unit to work only while that space stays between 45°F and 95°F. In practical terms the air coming out of the cellar face can be about 30°F cooler than the air the condenser breathes, so a hot utility room directly limits how cold the cellar can get.

Split systems relax that limit because the condensing unit can go outside, on a side yard pad or a roof, where the heat simply leaves. Ducted units sit between the two: the machine itself needs a ventilated space, but a duct can carry its exhaust further, and the cellar sees none of it. WhisperKool warns plainly against putting any condensing side in a closet or a small room, where the exhaust soon heats the very air the unit needs.

Source: CellarPro — 1800 Series owner's manual — Hole 1/4 inch larger than the unit, dedicated 15-amp circuit, 8-inch clearances, rear space at least as large as the cellar, 45–95°F ambient, air about 30°F below intake, 60 lb unit; WhisperKool — Ceiling Mount H.E. owner's manual — Holds 55°F with the condensing unit in air up to 120°F, dedicated circuits, no closet installs, 3 feet of clearance (5 ideal)

Close on a round insulated duct meeting a ceiling supply grille in a wine cellar, racks of unlabeled bottles below.
Close on a round insulated duct meeting a ceiling supply grille in a wine cellar, racks of unlabeled bottles below.

Noise, looks and where the water goes

In a tasting room or a glass-fronted cellar off a dining area, sound and sight matter as much as capacity. A through-the-wall unit shows a grille on the cellar side and makes its noise there. A ducted unit shows two grilles and can be dampened with flexible duct and rubber pads under the cabinet, both suggested in Wine Guardian's manual. A split system leaves the quietest cellar, with only the evaporator fan moving air inside.

Each layout also produces water from the air it cools, and each handles it differently. Some through-the-wall units let most of it evaporate and offer a condensate fitting as an option; ducted units drain by gravity through a built-in trap to a floor drain or a pump; ceiling evaporators rely on a small pump that lifts the water out.

  • Ask where the drain line will run before choosing a layout, especially over finished rooms.
  • A condensate pump adds one more part to check each season.
  • Ducted and split installs usually need a service opening big enough to reach filters and coils.

Source: Wine Guardian — Ducted split installation, operation and maintenance manual — About 25 feet of combined supply and return duct, insulated ductwork, rubber pads and flexible duct for noise, built-in drain trap

What each layout means for service years later

A through-the-wall unit weighs around 60 pounds in the CellarPro 1800 class and slides out of its opening, so a failed one can be examined on the bench or swapped for a unit with the same footprint. A ducted unit stays in its mechanical space, and the question becomes whether a technician can reach its panels; WhisperKool asks for at least 3 feet of clearance around its equipment, 5 being better.

A split system is closest to central air conditioning. Any work that opens the refrigerant circuit, from a leak repair to replacing the condensing unit, falls under EPA's Section 608 rules, which require the technician doing it to hold that certification. Plan for access to the line set where it passes through walls and ceilings, because that is where a technician will need to look.

Matching a layout to a cellar you already have

A basement cellar with a large unfinished room next door suits a through-the-wall unit. A cellar surrounded by living space, or one with glass on several sides, usually points toward ducted or split equipment so the heat and the noise go elsewhere. A cellar built under a stair or in a closet-sized room often has nowhere for exhaust at all, and only a split system solves that.

Source: CellarPro — 1800 Series owner's manual — Hole 1/4 inch larger than the unit, dedicated 15-amp circuit, 8-inch clearances, rear space at least as large as the cellar, 45–95°F ambient, air about 30°F below intake, 60 lb unit; WhisperKool — Ceiling Mount H.E. owner's manual — Holds 55°F with the condensing unit in air up to 120°F, dedicated circuits, no closet installs, 3 feet of clearance (5 ideal); US EPA — Section 608 technician certification — Technicians who maintain, service, repair or dispose of refrigerant-containing equipment must be certified under Section 608

A couple lifting a bottle from a lit stone-walled wine cellar, the cooling unit's grille high on the far wall
For the heart of your home.

Questions
owners ask.

Can a through-the-wall unit exhaust into a garage?
Only if the garage stays inside the maker's operating limits all year. CellarPro rates its 1800 series for surrounding air between 45°F and 95°F, and many garages in hot or cold climates pass one end of that in summer or winter.
Is a ducted unit the same thing as a split system?
No. A ducted self-contained unit keeps the compressor and both coils in one cabinet and moves cellar air through ducts. A split separates the coils into two units linked by refrigerant piping, which is why it needs a refrigerant technician to install.
Which layout handles a cellar with a glass wall best?
Glass adds so much heat that the unit usually has to be sized up, and a larger compressor in the cellar wall is louder. Ducted and split equipment move that bigger machine elsewhere, which is why glass-fronted cellars usually use one of them.
Can I switch from a through-the-wall unit to a split later?
Yes, but it is a new installation: a fan coil location, a drain route, a line set path and a place for the condensing unit. The old wall opening then needs to be framed, insulated and sealed like the rest of the cellar.

The problems
behind it.

Each has a page of its own: what it usually means and the causes in the order worth checking.

All 17 problems
A small stone-walled wine cellar with dark wooden racks full of unlabeled bottles lying on their sides, a through-the-wall cooling unit grille set high on the far wall and a round dial thermometer standing in a glass of water on a tasting shelf in front. The collection is exposed

Wine Cellar Too Warm

6 causes, cheapest first

 A narrow storage closet with its door wide open, the louvered exhaust grille of a through-the-wall cellar cooling unit set into its back wall, stacked cardboard boxes pressed close in front of the grille and a faint heat shimmer in the air. Problem

Cellar Cooling Unit Exhaust Overheating

5 causes, cheapest first

 The exhaust side of a through-the-wall cellar cooling unit in a finished family room, its louvered grille set into a painted wall above a low bookshelf, a closed glass-paneled door to the lit wine cellar beside it showing racks of unlabeled bottles. Problem

Cellar Cooling Unit Loud or Vibrating

5 causes, cheapest first

 The cellar-side grille of a through-the-wall cooling unit high on a plastered wine cellar wall, a dark wet streak running down the plaster below it toward a wall outlet, wooden racks of unlabeled bottles along the side wall and a folded towel on the tile floor. The collection is exposed

Cellar Cooling Unit Leaking Water

6 causes, cheapest first

When it needs
a technician.

The repairs on the right are where this guide ends when the checks do not settle it.

Cellar cooling load and room check

Measuring the cellar as the cooling unit sees it: insulation, vapor barrier, door, glass and the heat load, to show whether the unit can ever keep up.

Split-system cellar line set repair

Repairing, reinsulating or rerunning the copper lines and control cable that join the cellar evaporator to its outdoor or remote condensing unit.

Cellar condensate drain and pump repair

Clearing and rerouting the line that carries water off the cellar coil, and repairing the condensate pump where the water has to travel uphill.

Wine cellar cooling diagnostic visit

A visit that reads the cellar, the room the heat goes to and the cooling unit itself, and ends with one named cause, whether it is a part or the room.

More in
choosing and comparing.

Through-the-wall, ducted or split, how big a unit a cellar really needs, and whether an aging cellar system deserves another repair or makes way for a new one.

The whole section
Which system suits the room, and keep or replace

Sizing a cellar cooling unit: heat load, not cubic feet

Reading a maker's load chart, the glass, walls and summer air that volume hides, and the runtimes that show a unit is too small or too big for its room.

 Which system suits the room, and keep or replace

Repair or replace a cellar cooling unit: check the room before the machine

Keeping the collection safe while you decide, which parts are routine at any age, why a hot exhaust space ages compressors and what replacing a split system involves.

 Guides

All 18 guides

Six sections, by what you are trying to find out.

Back to your everyday

Read it and still not sure?

Book with what you checked and the model number, and the technician starts where the guide stopped.

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