Every cooling unit produces a certain amount of Total BTUH (British Thermal Units per Hour), which is the sum of Sensible BTUH (lowers the temperature) and Latent BTUH (lowers the relative humidity).
Because wine cellar cooling units are designed to reduce temperature while preserving humidity, look for equipment where the Sensible BTUH is a high percent of the Total BTUH. This percentage (calculated as Sensible BTUH divided by Total BTUH) is known as the SHR (Sensible Heat Ratio). The SHR for CellarPro cooling units is greater than 90%, which means that CellarPro units provide maximum cooling power without stripping out humidity from the cellar environment. *
Note that wine cellars should be properly constructed and airtight, to minimize the infiltration of ambient air into the wine cellar. If the cellar is not airtight, ambient air (and humidity) will infiltrate into the cellar, which will lower the SHR and therefore reduce the cooling power of the cooling unit.
In summary, BTUH is commonly used to measure the amount of heat a cooling unit can remove from the air within 1 hour. Whereas HVAC equipment is designed to remove both heat and moisture from the air, wine cellar refrigeration equipment is designed to remove heat while maintaining much higher humidity levels in the air. Therefore, installers should focus on Sensible BTUH, not total BTUH, when evaluating wine cellar refrigeration equipment for specific projects and across brands.
* CellarPro Sensible BTUHs are calculated assuming 55F cellar temperature, 60% relative humidity and 95F ambient for all units except 1800 units, which are calculated assuming 85F ambient.