Abstract: A dew point temperature measuring apparatus is positioned in a sample flow channel that withdraws a sample of a gaseous atmosphere within an enclosure for measuring the dew point temperature of the gaseous atmosphere from which its humidity may be determined. The dimensions of the sample flow channel and the velocity of the gas flow past the dew point temperature measuring apparatus is controlled to assure that the flow is laminar in order to avoid unwanted heat transfer between the sample gas and the dew point temperature measuring apparatus. The dew point temperature measuring apparatus includes a pair of sensors positioned side-by-side in a top wall of the sample flow channel.

Abstract: Apparatus for determining the relative humidity of an atmosphere by measuring the dew point of the atmosphere. The dew point is measured by lowering the temperature of a condensing or sensing surface associated with a heat flow sensor. When condensation begins to occur this is detected by the heat flow sensor as a change in the rate of heat flow through the condensing surface. In one embodiment a pair of heat flow sensors are employed, one maintained at a slightly lower temperature than the other. The sensors are connected in series opposition so that output signals due to background or convective heat transfer are cancelled, any change in the combined output signal of the two sensors then indicating heat flow resulting from condensation. The temperature of the cooler face will be the dew point temperature. Two arrangements of sensors are disclosed.

Abstract: A control apparatus for regulating a building perimeter temperature change system, which may be a heating system, a cooling system, or both. The control apparatus operates in conjunction with a central heating system which operates to adjust temperatures in the building. The building is characterized by net heat gains or losses at the building perimeter. These net heat gains and losses are made up by the building perimeter temperature change system under the regulation of the present control apparatus. The apparatus includes a heat flow sensor for mounting upon an exterior building element to generate a sensor signal proportional to the direction and magnitude of heat flow to or from the building element. A controller responsive to the sensor signal operates the temperature change system so that the rate of perimeter heating or cooling is directly proportional to the measured rate of heat loss or gain through the building element.