US 11,927,362 B2
Preventing evaporator coil freeze during re-heat dehumidification
Rakesh Goel, Irving, TX (US); and Siddarth Rajan, Addison, TX (US)
Assigned to Lennox Industries Inc.
Filed by Lennox Industries Inc., Richardson, TX (US)
Filed on Nov. 28, 2022, as Appl. No. 17/994,523.
Application 17/994,523 is a continuation of application No. 17/181,174, filed on Feb. 22, 2021, granted, now 11,561,015.
Prior Publication US 2023/0088937 A1, Mar. 23, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. F24F 3/14 (2006.01); F24F 3/153 (2006.01); F25B 47/00 (2006.01); G05B 15/02 (2006.01)
CPC F24F 3/1405 (2013.01) [F24F 3/153 (2013.01); F25B 47/006 (2013.01); G05B 15/02 (2013.01); F24F 2003/144 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method of preventing evaporator coil freeze in a heating, ventilation and air conditioning (HVAC) system operating in re-heat dehumidification mode, the method comprising:
determining, by a controller, a reference saturated suction temperate (SST) via a sensor disposed on an exterior surface of an evaporator coil in the HVAC system, the evaporator coil comprises a plurality of evaporator circuits assigned to a plurality of compressors in the HVAC system, wherein the determining the reference SST comprises determining a plurality of SSTs via a plurality of sensors disposed in relation to the evaporator coil and determining a minimum SST of the plurality of SSTs, wherein the minimum SST is the reference SST;
determining, by the controller, whether the reference SST is below a minimum SST threshold;
responsive to a determination that the reference SST is below the minimum SST threshold, determining a decreased compressor speed; and
modulating, by the controller, a variable-speed compressor in the HVAC system to operate at the decreased compressor speed, the decreased compressor speed varies at least one of linearly and non-linearly with the reference SST between a first value and a second value.