Abstract: A geothermal well apparatus which includes the well casing head, the expansion spool, an improved hanger spool which both supports and allows communication to a tubing string through the hanger spool and a master valve which is positioned above the hanger spool so that the presence or absence of a tubing string within the well supported from the hanger spool will not prevent the operation of the master valve. This improved hanger spool structure allows the use of the injection tubing string support and communication thereto solely by and through the hanger spool. The hanger which supports the tubing string is landed within a pocket in the flow passage of the hanger spool and the weight of the string provides the setting force for the sealing means carried by the hanger. A holddown screw is included to retain the hanger in it landed and sealed position within hanger spool.