Trane International Inc.

James Thomas Schaefer

Kevin B Mercer

Jonathan David Douglas

John Raymond Edens

Alan Dale Marble

Steven A Tice

Gary Lee Sapp

Kristin Lyn Schaefer

Gregory F Walters

A system and a method are provided for returning oil in a heating, ventilation, and air conditioning (HVAC) system by determining when an ambient zone temperature is equal to or less than a temperature limit and reversing a direction of refrigerant flow of the HVAC system based on the length of time. Also, a system and a method are provided for monitoring the length of operation in a first and a second heating mode and for reversing a direction of refrigerant flow based on the length of time operation occurs in the first and second heating modes. A system and a method having a first compressor, a first heating mode, a second heating mode, a defrost mode, and a controller is disclosed. The controller selectively controls initiation of the defrost mode in response to an HVAC system operating in a heating mode of operation for a predetermined amount of time.

System and Method for Oil Return in an HVAC system

Vapor compression air conditioning systems are provided with a flow restrictor for transferring working fluid to and from at least one of the compressor low pressure inlet conduit and compressor high pressure outlet conduit to provide for accurate charge adjustment to achieve predetermined fluid sub-cooling. Pressure and temperature measurements are taken at a condenser fluid outlet conduit and provided to a microcontroller for determining fluid sub-cooling and comparing sub-cooling with a predetermined target sub-cooling. A charge addition or recovery apparatus may include a solenoid valve controlled by the microcontroller to more accurately control the addition or recovery of refrigerant fluid charge.

System and method for controlling working fluid charge in a vapor compression air conditioning system

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Tyler, TX, United States of America

James Thomas Schaefer