No. 871 is an electrically-heated 2000 degrees F gas-heated box furnace from Grieve, currently used for heat treating and high temperature testing. 650,000 BTU/HR are installed in three modulating natural gas burners with a floor mounted combustion air blower. Workspace dimensions are 30" wide x 48" deep x 30" high. The unit has 7" insulated walls comprised of 5" of 2300 degrees F ceramic fiber and 2" of 1700 degrees F block insulation. The 6½" floor insulation is made of 4½" of 2300 degrees F firebrick and 2" of 1900 degrees F block insulation. The plate hearth is made of firebrick and is supported by firebrick piers. Controls onboard No. 871 include a Partlow MRC 7000 recording and programming temperature controller and an electrically-operated vertical lift door.