WINE CELLAR REFRIDGERATION
I have installed over 100 wine rooms in my years as an HVAC contractor and am no longer surprised at what some customers expect their room to be capable of doing in regards to temperature. Red and white wines are stored at different temperatures and yet some customers think they can keep the room at two distinct temperatures with an invisible curtain separating the red and white. I have had calls from customers after proudly leaving them with a custom wine room to say they cannot keep salad, fruit and vegetables cool enough in the room. A walk-in cooler is different from a wine room and different from a room where you make your own wine.
The key to a properly conditioned wine room is the humidity. The factors that will affect the humidity in a wine room or cellar are the temperature drop across the cooling coil, the length of the run cycle, number of air exchanges and the moisture content of the product in the room. Too little humidity and the corks will dry out, too much humidity and there will be mold in the room.
Any air conditioning system is designed to lower the temperature 20 degrees F. across the cooling coil which is ideal for removing humidity for human comfort. A wine room cooling unit is designed for only 10 degrees F. drop across the cooling coil. The lower temperature differential will reduce the amount of moisture removed.
The designs of some wine rooms can boggle ones’ mind. A well designed wine room could be the feature room of the home complete with marble table and linen table cloth for sampling the wine to custom millwork, in floor lighting and etched glass walls. Systems for cooling wine rooms can range from a split system unit as shown in picture #37 of our gallery to cooling coils that are ceiling mounted (quite obtrusive in appearance) to console units that can be “built in” to custom millwork.
The unit that feeds the cooling coil (called the condenser) can use water or air to act as the median to change the freon from vapor to liquid. This item deserves some explanation and consideration.
Most air conditioners and domestic refrigerators are what we call air cooled. This is where the condensing unit passes ambient air over the condenser coil(s) to reject the heat that is absorbed at the (evaporator) cooling coil. With an air conditioner, the heat that is rejected is outdoors at the condensing unit. With a wine room air cooled unit the condenser is located in the basement, usually in the mechanical room and the heat rejected stays in the house. Most basements are predominantly cold year round so this added heat source is not totally unwelcome.
If you have a water cooled condenser there is no fan making noise, but a water jacket around the freon piping. The water absorbs the heat from the freon and the water then goes down the drain. The cost to operate a water cooled unit is much higher as it uses water at a rate of 1 ˝ gallons per minute per ton of cooling capacity. (The average wine room is 1 ton or less in capacity.) Your water consumption is metered and most municipalities also charge a sewer tax for the water that you use. The water cooled system could operate for up to 16 hours per day using (16 hrs. x 60 minutes x 1 ˝ gallons) 384 gallons of water per day.
If you are using a well instead of city water and saving on your water bill, the problem that occurs is with the high mineral content fouling up the piping. The benefit of the water cooled system is that the condenser can be installed right in the wine room under a vanity or sink that is quite typical as there is no heat rejection from the condenser and it is right close to the plumbing and drain for connections. The water cooled units make less noise, use less hydro as there is no fan and also require less maintenance.
Sizing of the refrigeration equipment for a wine room is done the same way that an air conditioner is sized for the rest of the home. In this case a “Heat Gain” calculation is performed considering the dimensions of the room, lighting, wall construction and materials, insulation, ambient temperatures and the amount of wine being stored at what temperature. The heat gain calculation will provide the BTU rating. Todays’ construction materials and insulations can reduce the required amount of cooling to the point that is almost impractical to install refrigeration for the room.
If you are planning a wine room, be sure to rough in a power source to where the evaporator and condenser is to be located and make sure a drain is available. If water cooled equipment is used there must be plumbing available within access of the condenser. If air cooled equipment is to be used the refrigerant tubing must be roughed in between where the condenser and evaporator are being installed and must be the proper size for the BTU rating of the room. A thermostat is not necessary if you want to operate the temperature based upon the setting of a control that cycles the unit based upon refrigerant pressures, but thermostats are available if you like the flexibility of being able to change settings.
There is also an ideal temperature sensor that is inserted into a “dummy bottle” of wine, filled with water that truly measures the temperature of the product and not the air. This method prevents cycling the refrigeration on every time someone opens the door to retrieve a bottle of wine. It is now apparent that a number of things need to be “roughed in” before finishing a basement, but this also spreads out the cost over a period of time.
If your cellar is not going to contain 100 bottles or more, there is no need for a wine room and perhaps one of the new designer wine refrigerators would be more suitable and a lot less costly to get up and running.