9 - 2 RTHC-IOM-1C
Oil Sump Level Check
The oil level in the oil sump can be measured to give
an indication of the system oil charge. Follow the
procedures below to measure the level.
1 Run the unit fully loaded for approximately 20
minutes.
Note: Operating the unit at minimum load tends to
lower oil sump levels to as low as 2”, well below the
normal 4.5” to 6.0” levels. This is because the
evaporator tends to hold more oil at minimum load
conditions. Before adding any oil, obtain an oil level
reading near a full load operating condition.
2 Cycle the compressor off line.
CAUTION: Never operate the com-
pressor with the sightglass service
valves opened. Severe oil loss will
occur.
Figure 33
Determining Oil Level in Sump
3 Attach the 3/8” or 1/2” hose with a sightglass in
the middle to the oil sump drain valve and the
condenser service valve at the top of the
condenser.
4 After the unit is off line for 10 minutes move the
sightglass along the edge of the condenser
tubesheet at the same height of the oil sump.
5 The level should be between 2” and 5” from the
bottom of the oil sump. If the level appears to be
above 8”, the oil sump is completely full. Most
likely more oil resides in the rest of the system
and some oil needs to be removed until the level
falls between 2” and 5” in the oil sump.
6 If the level is below 2”, there is not enough oil in
the sump. This can occur from not enough oil in
the system or more likely, oil migration to the
evaporator. Oil migration can occur from a low
refrigerant charge, gas pump malfunction, etc.
NOTE: If the oil is logged in the evaporator confirm
the operation of the gas pump. If the gas pump is not
functioning properly all oil will be logged in the
evaporator.
7. After the level is determined, close the service
valves and remove the hose/sightglass assem-
bly.
Removing Compressor Oil
The oil in the compressor oil sump is under a
constant positive pressure at ambient temperature.
To remove oil, open the service valve located on the
bottom of the oil sump and drain the oil into a suitable
container using the procedure outlined below:
CAUTION
CAUTION: Due to the hygroscopic
properties of the POE oil, all oil must
be stored in metal containers. The oil
will absorb water if stored in a plastic
container.
1 Connect a line to the oil sump drain valve.
2 Open the valve and allow the desired amount of
oil to flow into the container and close the
charging valve.
3 Measure the exact amount of oil removed from
the unit.
Sightglass
3/8” or 1/2” hose
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