ISO 9869 U-value Testing Wall Heat Transfer Performance Tester The ISO 9869 Wall Heat Transfer Performance Tester is developed in accordance with testing requirements for building envelope heat transfer coefficients specified in EN ISO 9869-1 and GB/T23483-2009. This instrument is dedicated to on-site detection of heat transfer coefficients for building walls and roofs. Product Overview Mount heat flow meters and temperature sensors on inner wall surfaces, with temperature