Wine Cellar Split System Basics

Definitions Split System – A cooling unit that “splits” the cooling coil and the condenser apart into two remote pieces. Condenser – The outdoor half of a split system, this is where the hot freon gas is cooled back to into a liquid form and sent back to the cooling coil to absorb heat from the cellar. As the freon absorbs heat it changes state into a gas and returns to the condenser to discharge the heat gain into the ambient air. Cooling coil – The cooling coil is a freon cooled heat exchanger that air is drawn or pushed through to extract heat from the cellar. This could be mounted directly inside the room as a fan coil unit or mounted remotely as a ducted airhandler.

Definitions FCU (Fan Coil Unit) – A surface mount cooling coil that mounts inside, typically on the ceiling of the cellar. Best for retro fit installations or cellars without adjacent spaces for a ducted airhandler. Ducted Airhandler- Unit that contains the cooling coil outside the cellar, allowing for a supply and return duct to be run to and from the cellar. Best choice for applications appearance and low noise are critical. Requires a space adjacent to the cellar to locate the unit and insulated duct work for supply and return air. Note: Mounting outside the cellar in warmer air and the load from the length of the ductwork will increase the size of your system.

Definitions Supply Air- The air from the cellar that has been cooled by the cooling coil and is being supplied to the cellar. Return Air- The warm air returning to the cooling coil to have the heat removed. Once through the coil it becomes supply air.

Definitions Lineset – The two copper refrigeration pipes that run between the two pieces of a split system. One side carries the freon in a gas state and the other handles freon in a liquid state. They are normally bundled together and insulated. The two lines are are always slightly different sizes as the freon takes up more volume in a gas state. Condensate – The water byproduct caused by the temperature difference of the warm air crossing the cooling coil. This normally collects on the surface of the coil “fins” and then drips down into a collection pan to be drained away. As a result every fan coil or airhandler must gravity drain into a drain or a condensate pump.

Definitions Condensate Pump – Small pump mounted on top of a small reservoir, the pump is triggered by a float switch to empty the reservoir at a certain fill level. These pumps have a maximum lift rating called total equivalent head that determines their ability to push water upwards. If you exceed that rating the water will fall back down and flood the reservoir.

Definitions Total Head Pump Rating – The maximum distance the condensate pump can push water up from the source and still hold up the weight of the water. The closer you get to reaching the maximum rating the lower the output of the pump will be. At the point of total head the pumps output will be zero as it can only hold the weight of the water at that distance. Note: That 90 degree bends, reductions in size, valves or long horizontal runs will reduce the output rating.

Definitions PLC – Programmable Logic Control. This is the type of control we use in our split systems. Normally you find this type of control in large buildings or in building automation. We use this type of control because we can program it to react to the array of sensors we put in the cooling system to provide the best cellar control possible.

Definitions BTU – British Thermal Unit, a standard measurement of heat BTUH – The number of BTU’s that a system can handle per hour Heat load – The total amount of heat gained inside the cellar that will infiltrate in through the walls, door or glass surfaces. This is expressed in terms of BTU. Load calculation – A process in which the heat load, air volume, infiltration, surrounding temperatures, ambient exterior temperature are factored together to arrive at a cooling system size.

Key Terms Line voltage- 110volt (wall plug), 208 or 220/240volt single phase 60hz Low voltage- 24volt control wiring, small wiring used to send control impulses or sensor readings R-134A- The type of freon we use, it is the latest product and most environmentally friendly Equipment pad- Small concrete platform for the outdoor (condensing) unit to sit on, or it can be bought pre-made from synthetic material Service disconnect- Method of disabling the power supply to the units for service. Can be a box with a switch, a service lock out or simply a plug to unplug (preferred method for ease of rough in and installation). This must be mounted in view of the equipment such that a service person can see the status of the power to the unit while working on it.

Key Terms Delta T- Difference or change in temperature. Example: Delta T between the hallway and the wine cellar might be 25 degrees F Set Point- The selected temperature targeted for the cellar, cycles the unit off at this point. Cooling band- The range above the set point which triggers the unit to cycle on. TXV (TEV)- Thermal Expansion Valve which is installed in the cooling system to actively meter the flow of freon to the cooling coil depending on conditions. EPR – Evaporator Pressure Regulation. Regulates the low pressure at the cooling coil, can be used to change the delta T at the coil.

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