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EN/06.2016/i01 © STULZ S.p.A. – all rights reserved
WPA ExPlOrEr OrIGINAl INSTrUCTIONS
8.3.5 Exchange of filter drier
To be checked: filter drier, shut-off valve RG3-RG4
WPA060, WPA070: welded filter
WPA080 - WPA200: cartridge filter
To exchange the filter drier it is sufficient to evacuate the pipe section in which the filter drier is
installed.
Close the shut-off valve (RG3 or RG4, see "4.4 Piping diagrams" at page 24 ). The solenoid
valve upstream the expansion valve is closed when the compressors are switched off. By the
service valve on the lid of the filter drier, you can evacuate the refrigerant from the section now.
• WPA060, WPA070: de-soldering the old filter and install the new filter.
• Other sizes: remove eight M8 screws at the front side of the filter and pull out the cartridge.
Introduce a new cartridge and refill the evacuated refrigerant.
Open the shut off valves RG3 and RG4.
8.3.6 HP switch
To be checked: high pressure switch
When the
High Pressure
limiter triggers, the compressor is
switched off without delay. Before the restart and after the
elimination of the error, the HP switch must be reset by press-
ing the reset button. You can change the action value only
after having removed the adjustment lock. Turning the adjust-
ment screw counterclockwise reduces the action value.
A check of the tripping function of the high pressure limiter
(e.g. by cutting down the condenser fan and forcing a high
Adjustment screw
Adjustment lock
HP switch with reset button
pressure) is not possible without changing the action value, as
there are, on behalf of the C2020 electronic controller, further
monitoring functions via the high pressure sensor, which inter-
venes in the compressor control (high pressure management,
compressor envelope control). A change of the action value
(e.g. by reduction), however, bears the risk that this one is not
exactly readjusted after the check has been executed. The
scale on the case does not provide sufficient accuracy.
8.3.7 lP switch
To be checked: low pressure switch, shut-off valves RG3-RG4
This function is not applicable to WPA060 and WPA070 (shut-
off valves RG3-RG4 not installed)
Check the correct function of the low pressure switch by step
wise closing the shut-off valve RG3-RG4 on the refrigerant
LP switch with automatic reset
circuit, while the compressors are running. Check by means of the low pressure gauge in the
compressor section, whether the low pressure switch trips at 2,4 bar. When the LP switch trips,
the compressor is switched off without delay. If the pressure switch has tripped too early (e.g. at
4,0 bar), you can reduce the threshold by turning counterclockwise the adjustment screw on the
top side of the pressure switch after having removed the adjustment lock.
