A new configuration including liquid solar thermal collector integrated with fin and tube heat exchanger is proposed as solar air heater. Proposed system is modelled and optimized considering rate of heat transfer and total annual cost (TAC) as objective functions. 16 design parameters for both collectors and heat exchanger including water and mass flow rates are considered and optimized. It was found that, the maximum efficiency for the optimum rate of heat transfer could reach to 0.6359. Moreover, the higher value of air mass flow rate is required than the water mass flow rate. In addition, air to water mass flow rate ratio increases for the rate of heat transfer in the range of 0-60 kW while decreases for the higher values of 60 kW. In the optimum collector design parameters, the higher values of both collector length and width are selected to improve the rate of heat transfer and the effect of collector length is found stronger. (c) 2020 Published by Elsevier Ltd.