-SCS CONDENSER IOM MANUAL
8. Replace the Schrader valve cores if you removed them
during the evacuation steps. You may now introduce the
refrigerant charge through the Schrader valves.
2.7.4 Refrigerant Charging Procedures
R407C and R410A refrigerant must be weighed in when
performing the charge. Ensure an adequate supply of
refrigerant is available before beginning. Referring to Section
2.7.2, calculate the minimum amount of refrigerant needed
for your system.
When charging a system using a blended refrigerant, it is
essential that the composition of the refrigerant is maintained.
To ensure correct composition, introduce the refrigerant
(R407C or R410A) into the system in liquid form rather than
vapor form. Cylinders which are not provided with dip tubes
should be inverted to allow only liquid refrigerant to charge
the system. Keeping the temperature of the cylinder below
85 °F will help to maintain the correct refrigerant composition
while the cylinder is emptied.
CAUTION
POE oil is used in systems with R407C or R410A
refrigerant. POE oil quickly absorbs moisture when exposed
to air. High POE oil moisture levels react with refrigerant to
form acid which results in system contamination. Keep the
entire system sealed as much as possible and minimize
exposure of the POE oil to outside air.
NOTE: Refrigerant charging must be performed by a
qualified air conditioning technician. STULZ recommends
using the services of our Field Service Department to assist
in start-up and commissioning. We have assembled a highly
qualified team of experienced industry professionals who
provide expert start-up services anywhere in the world.
They will ensure your equipment is correctly installed and is
operating properly. This will help to ensure your unit
provides years of trouble free service while operating at its
highest efficiency. They will also enter the necessary
Information for you on the Warranty Registration and Start-
up Checklist and ensure it is filed with STULZ for your
warranty protection.
WARNING
If refrigerant gas is released in an enclosed area, it may
accumulate in low areas and near the floor displacing
available oxygen. If a major leak occurs, there is a risk of
asphyxiation. In such case the area
should be immediately evacuated and ventilated.
Personnel should remain away from the area until
it is determined to be safe.
INITIAL SYSTEM CHARGE
Follow the step by step instructions below to charge systems
using R407C and R410A refrigerant. The initial charge will
be performed by introducing liquid refrigerant (R407C or
R410A) to the discharge side of the compressor or an
available liquid line port with the A/C unit turned Off.
1. Bleed air from hoses and break the vacuum by supplying
liquid refrigerant (R407C or R410A) to the discharge
port near the compressor until the pressure is equalized.
This holding charge allows the low pressure switch to
hold enabling the compressor to operate throughout
the process of charging the system.
FINE TUNING THE SYSTEM CHARGE
Once the initial charge is completed, additional refrigerant
will need to be added with the unit running until the superheat
temperature can be maintained between 12–15 °F.
CAUTION
An adequate heat load must be supplied to
ensure a proper charge.
2. Disconnect the refrigerant cylinder from the discharge
side of the compressor and connect it to the suction side.
3. Start the A/C system and use the system controller to
lower the room temperature setpoint 3–5 °F below actual
room temperature thus ensuring cooling remains on as
the unit is charged.
When fine tuning the charge during low ambient conditions it
will be necessary to restrict the airflow across the condenser
coil to raise the pressure. The fan closest to the header must
be running. Refrigerant R407C operates at a lower pressure
than R410A. When fine tuning the charge, ensure the
pressures are correct for the type of refrigerant used. Refer to
the tables in section 2.8 for the operating temperatures and
pressures for the type of refrigerant used in your system.
2.7.4.1 0 ºF Fan Cycling and -20 ºF
Variable Speed Control
The following instructions are for charging systems provided
with condenser fan cycling or variable fan speed control
during low ambient conditions using R407C or R410A
refrigerant.
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