User's Manual

6 Using the product
13
Key functions
Representation Explanation
[▲] or [▼]
Changing the refrigerant
[R, Start/Stop] Confirm the setting and exit the refrigerant
menu.
Available refrigerants
Representation Explanation
R... Refrigerant number of refrigerant acc. to
ISO 817
T... Special Testo designation for certain
refrigerants (T8 = T1234yf)
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no refrigerant selected.
Example: Setting refrigerant R401B
1. Press [▲] or [▼] several times, until R401B flashes.
2. Press [R, Start/Stop] to confirm the setting.
Quitting the refrigerant selection
> Press [R, Start/Stop] or automatically after 30 s, if no other key
has been pressed.
6.1.3. Selecting the measuring mode
1. Press[Set] several times.
2. Select function with[▲] or [▼].
3. Save setting: press [Set].
- Measuring mode is dsplayed.
Display Mode Function
Refrigeration
system
Normal functionality of the digital manifold
Heat pump Normal functionality of the digital manifold
Automatic
mode
If the automatic mode is activated, the
testo 550 digital manifold automatically
changes the display of the high and low
pressure. This automatic change occurs
when the pressure on the low-pressure
side is 1 bar higher than the pressure on
the high-pressure side. During the
change, Load (2 s) is shown in the