File of 'raw' scientific data from Heat Recovery Units (HRUs) tested at Church Farm by staff at the National Institute for Research into Dairying. The data is recorded in notes, temperature and pressure charts, which include baseline information taken before the installation of HRUs and tests comparing an HRU Mark 6 with earlier machines, amongst the results of other experiments. The file includes some later notes added by researcher A.S. Cromarty.