James R Blanchard

US Patent:

43122264, Jan 26, 1982

Filed:

Nov 30, 1979

Appl. No.:

6/098866

Inventors:

Harold P. Adams - Norridge IL
Wesley L. Taylor - Glenview IL
James B. Blanchard - Green Bay WI

Assignee:

Mark Controls Corporation - Evanston IL

International Classification:

G01K 308
G01L 1302

US Classification:

73336

Abstract:

A comparator for selecting from two air sources, air which requires less energy to condition includes a humidity and a temperature sections for comparing relative humidities and dry-bulb temperatures of air from each of the sources. Each section comprises two chambers separated from each other by a diaphram which is displaceable in the direction of the chamber having a lower pressure. A temperature post is attached to the diaphram of the temperature section and a humidity post is attached to the diaphram of the humidity section. The pressure in each of the chambers is determined by the pressure signal generated by a transmitter and it indicates the sensed condition. The post of the humidity section coacts with the post of the temperature section to give an output signal indicating which of the two air sources has a lower enthalpy except that when the humidity of the outside air is lower than that of the return air. In that instance, the temperature section alone determines the output signal. The output signal is either high or low.