MULTI-VENDOR RTU RETROFIT CONTROLLER FIELD STUDY

Four different retrofit RTU controllers were tested on four 7.5 ton heat pumps serving office space at one building in San Diego. The operation of those units was alternated on a weekly basis from baseline to retrofit mode. Proper operation of the each controller was verified and the features of the controllers were compared to each other. Total heat pump electric power was measured at 1 minute intervals. The data was then re-sampled at hourly and daily intervals and was compared to various independent variables. Linear regression models were created to normalize for those independent variables and energy savings was calculated.