Cooling systems for small equipment rooms and methods of cooling small equipment rooms
A cooling system for an equipment closet in a building has a direct expansion cooling circuit. The cooling system has two basic modes of operation. A first mode where the direct expansion cooling circuit is off and transfer air from an area of the building outside the equipment closet is used to cool the interior of the equipment closet without any cooling provided by the direct expansion cooling circuit and a second mode where the direct expansion cooling circuit is on and provides direct expansion cooling that is used to cool the interior of the equipment closet.
1. A method of cooling an equipment closet in a building with a cooling system, the cooling system having a direct expansion cooling circuit that includes a compressor, a condenser having a condenser coil and a condenser fan, an expansion device and an evaporator having an evaporator coil and an evaporator fan that are arranged in the direct expansion cooling circuit, the method comprising:
disposing a cabinet at least partially in the equipment closet wherein at least the condenser is disposed in an upper portion of the cabinet and the evaporator is disposed in a lower portion of the cabinet;
separating the lower portion of the cabinet from the upper portion of a cabinet with a first wall to provide separate air flow paths through the upper portion of the cabinet and the lower portion of the cabinet;
operating the cooling system in a first mode of operation with the direct expansion cooling circuit off to cool an interior of the equipment closet with transfer air drawn in from an area of the building outside of the equipment closet and operating the cooling system in a second mode of operation with the direct expansion cooling circuit running to cool the interior of the equipment closet with air cooled by the direct expansion cooling circuit;
controlling operation of the cooling system with a controller by having the controller operate the cooling system in the first mode of operation when the controller determines that operating the cooling system in the first mode of operation will meet a cooling demand due to heat load in the interior of the equipment closet and having the controller operate the cooling system in the second mode of operation when the controller determines that operating the cooling system in the first mode of operation will not meet the cooling demand;
when operating the cooling system in the first mode of operation drawing transfer air in through a transfer air inlet of the lower portion of the cabinet from an area of the building outside of the equipment closet and surrounding the transfer air inlet of the lower portion of the cabinet and when operating the cooling system in a second mode of operation drawing transfer air in through the transfer air inlet in the lower portion of the cabinet and cooling it with the direct expansion cooling circuit;
creating a positive pressure in the interior of the equipment closet by the discharge of air with the evaporator fan through a cool air outlet of the lower portion of the cabinet into the interior of the equipment closet to force air in the interior of the equipment closet out through a hot air outlet of the equipment closet; and
wherein having the controller operate the cooling system in the first mode of operation includes having the controller operate the cooling system with the condenser fan off and the evaporator fan running and drawing transfer air in with the evaporator fan through the transfer air inlet of the lower portion of the cabinet and with the evaporator fan discharging this air out through the cool air outlet of the lower portion of the cabinet into the interior of the equipment closet; and
wherein having the controller operate the cooling system in the second mode of operation includes having the controller operate the cooling system with the condenser fan running and the evaporator fan running and drawing transfer air in with the condenser fan through a transfer air inlet of the upper portion of the cabinet and across the condenser coil to cool refrigerant flowing through the condenser coil and after this air passes across the condenser coil discharging this air with the condenser fan out through a hot air outlet of the upper portion of the cabinet into a ceiling space and also drawing transfer air in with the evaporator fan through the transfer air inlet of the lower portion of the cabinet and across the evaporator coil to cool the air with refrigerant flowing through the evaporator coil and with the evaporator fan discharging the cooled air out through the cool air outlet of the lower portion of the cabinet into the interior of the equipment closet.
2. The method of claim 1 including disposing the cabinet partially in the equipment closet and partially in the ceiling space above the equipment closet with the lower portion of the cabinet disposed in the equipment closet and at least a portion of the upper portion of the cabinet disposed in the ceiling space wherein at least the condenser is disposed in the portion of the upper portion of the cabinet disposed in the ceiling space, and with the condenser fan pulling air across the condenser coil and discharging this air through a hot air outlet in the upper portion of the cabinet into the ceiling space and away from the hot air outlet of the equipment closet through which the air from the equipment closet is exhausted into the ceiling.
3. The method of claim 1 including disposing the cabinet entirely within the equipment closet with a hot air outlet of the cabinet opening to the ceiling space above the equipment closet and with the condenser fan pulling air across the condenser coil and discharging this air through the hot air outlet of the cabinet into the ceiling space.