As a business guarantee, "on-site verification" is a necessary means. At present, the heat recovery products in the market are certified by the American HVAC AHRI. The AHRI official website will publish the efficiency data of all tested products and require the manufacturer to accept the "challenge test", which means that anyone can pass the application for the "challenge test" "Come to supervise, if the standard is not met, the manufacturer must bear the test costs and high fines. The authenticity of the performance of AHRI certified products is guaranteed, but the overall matching effect of the system on-site can only be understood through “on-site verification”.

The difficulty of field testing is that the project site often does not have the various test conditions of the laboratory. For example, the space between the heat recovery device and the rear surface cooler is often very short, the airflow enters the surface cooler before it is evenly mixed, and the temperature and humidity of the heat recovery outlet air cannot be measured correctly. Therefore, on-site testing generally uses indirect measurement methods such as “surface cooler flow method”. That is to measure the inlet and outlet water temperature and flow rate of the surface cooler under the conditions of running and stopping the fresh air heat recovery respectively, and convert to obtain the total heat efficiency that can be achieved when using heat recovery. For projects that can be qualified in the field verification, the project can generally meet the requirements in terms of implementation.

By adopting the above-mentioned technically and commercially mature methods and management measures, the original design intention of reducing the initial investment of the fresh air heat recovery can be safely realized in a suitable project.