Providing domestic hot water from conventional residential split system heat pumps

An improved environmental control system of the type having a split system electrically powered heat pump having an outdoor compressor, an outdoor coil, an outdoor fan, an indoor coil, an indoor fan associated with ducting, an expansion valve, a living space thermostat and interconnecting piping, the outdoor coil and the indoor coil carrying refrigerant therein, comprising:

• an unpressurized hot water tank storing hot water therein serving as a thermal store and having a tank thermostat therein set to a specified tank temperature range and two intertwined tank coils therein including a first tank coil carrying potable water to be heated from the thermal store and a second tank coil carrying hot refrigerant from the compressor as needed to maintain the specified tank temperature range in the stored hot water of the hot water tank, the hot water tank has an upper portion and a lower portion with the upper portion having an air-filled bladder that expands and contracts in response to water temperature in the tank;
• a valve matrix having an array of reversing valves capable of communicating refrigerant fluid and vapor and further having an array of solenoid operated valves and check valves associated with the reversing valves capable of selectively communicating refrigerant fluid and vapor with any of the compressor, the outdoor coil, the indoor coil, and the second tank coil;
• the living space thermostat having a desired temperature set point;
• a logic device controller operatively associated with the living space thermostat and the tank thermostat, with the expansion valve, and with the valve matrix, the logic device controller programmed to direct refrigerant through selected coils, and to operate the indoor fan, the indoor coil, the outdoor fan and the outdoor coil in response to signals from the living space thermostat and the tank thermostat calling for any combination of residential heating and cooling, tank water heating, and periodic outdoor coil defrosting in at least four programmed modes of valve matrix operation including a call for tank water heating, a call for space heating, a call for space cooling, and a call for a quiescent state, the programmed modes giving top priority to calls for tank water heating, providing concurrent tank water heating and space cooling, and providing the periodic outdoor coil defrosting from the thermal store in the hot water tank, all refrigerant flow being fully diverted by the valve matrix to only selected operative coils according to each programmed mode.