Viessmann AWO-M-AC 101.A06, Assembly And Servicing Instructions

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Measure Completed Notes
12
Leak detection
The following leak detection processes are suitable for systems
with flammable refrigerants:
Leak detection with electronic refrigerant detectors:
■
Electronic refrigerant detectors may not have the required sensi-
tivity or may need to be calibrated to the relevant range. Carry
out the calibration in refrigerant-free surroundings.
■
The refrigerant detector must be suitable for the R32 refriger-
ant to be detected.
■
The refrigerant detector must not contain any potential sources
of ignition.
■
Calibrate the refrigerant detector to the refrigerant used. Set the
response threshold to < 3 g/a, suitable for propane.
Leak detection with liquid leak detectors:
■
Liquid leak detectors are suitable for use with most refrigerants.
!
Please note
Liquid leak detectors containing chlorine may react with
the refrigerant. This could result in corrosion.
Do not use liquid leak detectors that contain chlorine.
Measures to take if a leak in the refrigerant circuit occurs:
■
Immediately extinguish all open flames in the vicinity of the heat
pump.
■
If brazing/soldering work needs to be undertaken to remedy the
leak, always extract all the refrigerant from the refrigerant circuit.
Purge the site to be brazed/soldered before and during the braz-
ing/soldering work with oxygen-free nitrogen.
13
Extracting the refrigerant
Removal and evacuation
When breaking into the refrigerant circuit to make repairs – or for
any other purpose – conventional procedures shall be used.
However, it is important that best practice is followed since
flammability is a consideration. The following procedure shall be
adhered to:
- remove refrigerant;
- purge the circuit with inert gas;
- evacuate;
- purge again with inert gas;
- open the circuit by cutting or brazing.
The refrigerant charge shall be recovered into the correct recovery
cylinders. The system shall be “flushed” with OFN to render the unit
safe. This process may need to be repeated several times.
Compressed air or oxygen shall not be used for this task.
Flushing shall be achieved by breaking the vacuum in the system
with OFN and continuing to fill until the working pressure is
achieved, then venting to atmosphere, and finally pulling down to a
vacuum. This process shall be repeated until no refrigerant is within
the system. When the final OFN charge is used, the system shall
be vented down to atmospheric pressure to enable work to take
place. This operation is absolutely vital if brazing operations on the
pipe-work are to take place.
Ensure that the outlet for the vacuum pump is not close to any
ignition sources and there is ventilation available.
14
Topping up the refrigerant
Charging procedures
In addition to conventional charging procedures, the following
requirements shall be followed.
– Ensure that contamination of different refrigerants does not
occur when using charging equipment. Hoses or lines shall be as