Fine offset HP2550 Operation Manual page 18

Figure .
Switch in down position.
5. Insert two AA batteries.
6. Verify the correct channel number (CH) and temperature units of
measure (° F vs. ° C) are on the display, as shown in
Figure 14: sensor LCD display
9. Close the battery door.
Figure 13: Dip Switch diagram
7.
8. Figure .
18
Switch in up position.
(1) temperature
(2) temperature units (° F vs. ° C)
(3) channel number
(4) relative humidity