A　plate　heat　pipe　heat　exchanger　for　use　in　a　room　ventilation　system　to　cool　or　heat　outdoor　fresh　air　was　designed　in　this　study.　One　fresh　air　duct　and　one　exhaust　air　duct　were　joined　with　the　heat　pipe　heat　exchanger　to　study　the　thermal　performance　of　the　thermal　recovery　system.　A　ratio　of　1　for　air　volume　flow　rate　between　fresh　and　exhaust　air　was　used　to　investigate　the　heat　recovery　effectiveness　and　the　change　in　fresh　air　temperature.　The　fresh　air　temperature　in　the　inlet　duct　was　controlled　in　the　range　of　27　to　40　degrees　C　under　summer　simulation　conditions　and　in　the　range　of　2　to　15　degrees　C　under　winter　simulation　conditions,　whereas　the　temperature　of　exhaust　air　was　controlled　at　approximately　24　and　18C　to　simulate　summer　and　winter　conditions,　respectively.　The　experimental　results　show　that　the　temperature　variations　of　fresh　and　exhaust　air　increase　with　increasing　inlet　fresh　air　temperature　under　summer　conditions　but　decrease　with　increasing　inlet　temperature　of　fresh　air　under　winter　conditions.　The　maximum　heat　recovery　effectiveness　of　the　plate　heat　pipe　heat　exchanger　was　58%　in　summer　and　62%　in　winter.　The　change　in　effectiveness　is　moderate　with　different　vacuum　levels.　At　a　vacuum　of　1　x　10(-3)　Pa,　the　maximum　effectiveness　occurred　when　the　filling　ratio　was　1:3.　The　experimental　results　showed　that　the　heat　pipe　heat　exchanger　gained　a　high　efficiency　of　heat　recovery　with　low　flow　resistance.　The　energy　conservation　effect　of　this　heat-pipe　heat　exchanger　was　evident.