A run around coil ventilation heat recovery system is analyzed in order to identify important performance factors. The aim of this investigation was to find the factors that influence the system performance, with focus on the brine side of the system. A test rig was built to provide measurements for the evaluation of the system behavior during different operating conditions. Results from measurements and calculations are presented.  Three significant factors that affect system efficiency have been identified, the brine flow rate, the concentration of glycol and the charge (pressure) of the system. In addition suggestions on possible further analysis are presented to the reader. It is also concluded that for many existing systems, the heat transfer resistance may be considered to be approximately constant throughout the year even considering the fact that the outdoor temperature changes significantly.