How are wine cellar cooling units rated?
Wine cellar cooling units are designed to cool the whole wine cellar so they are rated by cubic feet of a properly built, properly insulated cellar that has a vapor barrier. You have to remember that if you have glass, such as a window or glass door that is going to reduce the insulation value (yes even dual pane, thermal glass) and there will be heat transference. Cement, stone, brick, slate, tile and other materials that do not have insulation between it and the cellar will reduce the efficiency of a cooling unit. You can compensate by upsizing one size cooling unit, unless you have a excessive amount in which you may need to go even larger in order for the cooling unit to keep the cellar at a constant, cool temperature. A unit that is undersized may work for a while but it will burn itself out trying to keep up.
Air conditioning units should be rated at close to the intended operating temperatures and humidity. For a room air conditioner, this means rating around 72°F and 50% RH. For a wine cellar, this means around 55°F and 60%RH. Unfortunately, many wine cellar cooling units are listed with capacities based on room conditions rather than cellar conditions. This overstates their operating capacities by a factor of 35% to 50%.
