Wood pellet is solid biomass energy and one of renewable energy sources. In 2008, new and renewable energy (NRE) portion is 2.4% with respect to total primary energy in Korea. Korea government wants to increase new and renewable energy portion up to 6.1% by 2020 [1]. To achieve the target of NRE portion, Korea government has been establishing some policies, such as incentive policy, NRE mandatory use for public building and renewable portfolio standard (RPS) and so on. One of these policies is a domestic wood pellet boiler supply policy. But wood pellet boiler manufacturers who want to participate in the supply policy need a performance test result from a qualified test institute such as Korea Institute of Energy Research (KIER) and Korea Testing Laboratory (KTL). So we install a test facility to evaluate heating performance of a domestic wood pellet boiler semi-automatically. In order to achieve a thermal efficiency of a wood pellet boiler, it is very important to maintain heating water inlet and outlet temperature and water flow rate to be stable. We use 2 water passages in the system; one is circulation of a wood pellet boiler heating water passage and the other is a cooling circulation for removal heat from the wood pellet boiler. These 2 water passages exchange heat by a plate type heat exchanger. We control the flow rate of cooling water based on the wood pellet boiler water inlet temperature. With this system, temperature variation of boiler inlet and outlet temperature is less than 0.4 degrees C, that is +/- 0.2 degrees C which is important to evaluate boiler thermal efficiency. (C) 2012 Elsevier Ltd. All rights reserved.