Robert M Ray

US Patent:

D3643719, Nov 21, 1995

Filed:

Sep 16, 1994

Appl. No.:

D/028502

Inventors:

Robert A. Ray - Highland Village TX
Ronaldo S. Natividad - San Jose CA

Assignee:

Paccar Inc. - Bellevue WA

US Classification:

D12169

US Patent:

57017506, Dec 30, 1997

Filed:

Jun 26, 1995

Appl. No.:

8/494688

Inventors:

Robert W. Ray - Houston TX

International Classification:

F25B 1300

US Classification:

62160

Abstract:

A thermal zone demand controlled dual cascade arranged heat pump system and system controller for building spaces, having first and second heat pumps and having an air circulation system for circulating air to and from said thermal zones and including a conditioned air chamber having first and second heat exchange refrigerant coils being connected in refrigerant circulating relation respectively with the heat pumps. A plurality of thermal zone blowers conduct conditioned air, heated or cooled, from the conditioned air chamber to respective thermal zones of the building space. Electronic controller circuitry of the system is coupled for thermal demand control of the heat pumps and the thermal zone blowers for operation of the first heat pump to accommodate a predetermined range of thermal load and for operation of the second heat pump along with the first heat pump to accommodate a greater thermal load. The controller circuitry also controls selective operation of the thermal zone blowers as well as operation of the thermal zone blowers at low blower speed or high blower speed responsive to sensed conditions of thermal load. The electronic controller circuitry further provides for selective reversal of dual heat pump operation to compensate for unequal operational wear of the heat pump units.