Tests Prior To Compressor Start; Compressor Start; Lubrication / Oil Level Monitoring; Start - Bitzer HS.8551 Instructions De Service

• After commissioning, it may be necessary to add re-
frigerant: While the compressor is running, charge
with refrigerant on the suction side, preferably at the
evaporator inlet. Blends must be taken out of the
charging cylinder as a bubble-free liquid.

6.6 Tests prior to compressor start

• Oil level in the oil separator (in the sight glass
range).
• Oil temperature in the oil separator (approx. 15 ..
20 K above ambient temperature).
• Setting and function of the safety and protection
devices.
• Setpoints of the time relays.
• Cut-out pressures of the high-pressure and low-pres-
sure limiters.
• Cut-out pressure values of the pressure switches.
Record the setting.
• Check if the shut-off valves in the oil injection line
are open.
NOTICE
!
!
Do not start the compressor if it was flooded
with oil due to faulty operation! It is absolutely
necessary to empty it!
Internal components may be damaged.
Close shut-off valves, depressurize the com-
pressor and drain oil via drain plug on the com-
pressor.
In case of compressor replacement
Oil is already in the circuit. It may therefore be neces-
sary to drain off some oil.
NOTICE
!
!
In case of larger oil quantities in the refrigerant
circuit: Risk of liquid slugging when the com-
pressor starts!
Maintain the oil level within the marked sight
glass area!
• Mount a filter for bidirectional operation with perfor-
ated metal tubes around the inside and outside dia-
meter of the filter element.
• After several operating hours: Change the oil filters
and cleaning filters.
• If needed, repeat the operation, Oil change.
20

6.7 Compressor start

6.7.1

Lubrication / oil level monitoring

• Check the lubrication of the compressor directly after
the compressor start.
The oil level must be visible in the zone of both sight
glasses.
• Check the oil level repeatedly within the first hours of
operation!
During the start phase, oil foam may arise but its level
should decrease at stable operating conditions. Other-
wise high proportions of liquid in the suction gas are
suspected.
NOTICE
!
!
Risk of wet operation!
Maintain the discharge gas temperature well
above the condensing temperature: at least
20 K.
At least 30 K for R407A, R407F and R22.
NOTICE
!
!
Risk of compressor failure due to liquid slug-
ging!
Before adding larger quantities of oil: check the
oil return!
HS.85: If the oil monitoring system (F7) switches during
the start phase, see figure 10, page 16 or if the oil level
switch is triggered after the time delay (120 s), this in-
dicates an acute lack of oil. Possible causes are insuffi-
cient differential pressure or an excessive amount of re-
frigerant in the oil. Check the suction gas superheat.
6.7.2

Start

Restart, slowly open the suction shut-off valve and ob-
serve the sight glass in the oil injection line. If there is
no oil flow within 5 s, switch off immediately. Check oil
supply!
6.7.3 Set high pressure and low pressure switches
(HP + LP)
Check exactly the cut-in and cut-out pressure values
according to the operating limits by testing them.
6.7.4

Setting the condenser pressure control

• Set the condenser pressure so that the minimum
pressure difference is reached within 20 s after the
start.
SB-110-3