Seasonal performance of air conditioners: An analysis of the DOE test procedures: The thermostat and measurement errors

The assumption that the major factor in controlling the cycle rate of air conditioners is examined by studying a closed-loop feedback model consisting of a thermostat, a heating/cooling plant and a conditioned space. Important parameters of this model are individually studied to determine their influence on the system. It is found that the switch differential and the anticipator gain are the major parameters in controlling the cycle rate. Errors due to thermocouple response, thermocouple grid placement, dampers and nonuniform velocity and temperature distributions were also considered. Problems in these four areas are mathematically modeled and the basic assumptions are stated. It is found that major disagreement in measured capacity can arise in the these four areas and can be mainly attributed to test set-up differences even though such differences are allowable in the test procedures.