Abstract: Certain embodiments of an indoor unit (e.g., an indoor unit for a heat pump system) include: a housing comprising an exit-point on a wall-side of the housing, the exit point comprising a refrigerant line and the housing having a height of less than 11 inches; a heat-exchanger connected to the refrigerant line, wherein a portion of the refrigerant line that is external to the heat exchanger, and that runs internal to the housing and between the heat exchanger and an outdoor unit, runs substantially within a height-depth plane of the housing prior to exiting the housing and traverses less than 25% of a width of the housing; and a fan, wherein the indoor unit is configured to exchange at least 8000 BTUs/hour with a room and wherein the indoor unit produces a noise of 48 dBA or less.

Abstract: Heat pump systems, control systems for heat pumps, and methods of controlling heat pumps utilizing distributed control techniques are described herein. Examples of the control systems include multiple control devices distributed amongst a heat pump system. A first of the control devices is configured as a main control device to execute a model predictive control algorithm for the heat pump system. The other, remaining control devices are configured as a shadow control system to monitor the first control device. If a fault or failure occurs in the first control device, the shadow control system elects and initializes a second of the control devices as the main control device to continue executing the model predictive control algorithm uninterrupted. This allows the control system to dynamically react to faults or failures at any one part of the heat pump system while maintaining full operation of the functional parts.