An uninterruptible power supply (UPS) comprising: a housing defining an interior space ; a door operatively connected to the housing, the door being configured to be selectively opened and closed for accessing the interior space of the housing; an electrical system enclosed within the housing; at least one liquid cooling device mounted to a target component of the UPS disposed within the housing for cooling thereof, the at least one liquid cooling device defining a fluid conduit for circulating fluid therethrough; and a pumping module comprising at least one pump fluidly connected to the at least one liquid cooling device for circulating fluid therethrough, each of the at least one pump and the fluid conduit of the at least one liquid cooling device defining in part a liquid cooling circuit (Cl), the pumping module being mounted to the door, characterised in that : the pumping module is disposed on an exterior side of the door, the door defines at least one opening , and the UPS further comprises: an air-to-liquid heat exchanger configured for cooling air flowing therethrough, the air-to-liquid heat exchanger being mounted to the door on the exterior side thereof and being at least partially aligned with the at least one opening, the air-to-liquid heat exchanger comprising: a cooling coil for circulating fluid therethrough; and a plurality of fins in thermal contact with the cooling coil; and at least one fan contained within the housing when the door is closed, the at least one fan being configured to force air to flow through the at least one opening of the door and through the air-to-liquid heat exchanger. a housing defining an interior space ; a door operatively connected to the housing, the door being configured to be selectively opened and closed for accessing the interior space of the housing; an electrical system enclosed within the housing; at least one liquid cooling device mounted to a target component of the UPS disposed within the housing for cooling thereof, the at least one liquid cooling device defining a fluid conduit for circulating fluid therethrough; and a pumping module comprising at least one pump fluidly connected to the at least one liquid cooling device for circulating fluid therethrough, each of the at least one pump and the fluid conduit of the at least one liquid cooling device defining in part a liquid cooling circuit (Cl), the pumping module being mounted to the door, the pumping module is disposed on an exterior side of the door, the door defines at least one opening , and the UPS further comprises: an air-to-liquid heat exchanger configured for cooling air flowing therethrough, the air-to-liquid heat exchanger being mounted to the door on the exterior side thereof and being at least partially aligned with the at least one opening, the air-to-liquid heat exchanger comprising: a cooling coil for circulating fluid therethrough; and a plurality of fins in thermal contact with the cooling coil; and at least one fan contained within the housing when the door is closed, the at least one fan being configured to force air to flow through the at least one opening of the door and through the air-to-liquid heat exchanger. an air-to-liquid heat exchanger configured for cooling air flowing therethrough, the air-to-liquid heat exchanger being mounted to the door on the exterior side thereof and being at least partially aligned with the at least one opening, the air-to-liquid heat exchanger comprising: a cooling coil for circulating fluid therethrough; and a plurality of fins in thermal contact with the cooling coil; and a cooling coil for circulating fluid therethrough; and a plurality of fins in thermal contact with the cooling coil; and at least one fan contained within the housing when the door is closed, the at least one fan being configured to force air to flow through the at least one opening of the door and through the air-to-liquid heat exchanger. <EOS>