R407C Refrigerant - Marstair CXE Series Technical Manual

Charging the System:
1. Evacuate the system and interconnecting pipework ensuring the service valves are fully open.
2. Allow the evacuated system to draw in the majority of the refrigerant charge.
3. The final charge should be adjusted with the system running.
4. All units are fitted with head pressure control. The link wire across the orange terminals allows
the fan to operate at full speed. THIS SHOULD BE REMOVED AFTER CHARGING
5. A random start delay of up to 1 minute occurs when mains is first applied. A 3 minute delay occurs
between successive compressor operations on all systems.
6. Refrigerant and polyolester oil should be introduced through the Schrader valve in the service port on
the suction service valve on the outdoor unit. Ensure the refrigerant is the correct type, as shown
on the rating plate. R407C must always be added in the liquid state. See indoor installation
instruction for refrigerant charge weight.
7. Run the system for a few minutes to allow it to stabilize. Where possible, charge to a sweat
line on the evaporator. Typical suction pressures on short lines at UK conditions, with high
speed evaporator fan, high speed condenser fan, should be; low temperature system
approx 4.4 bar (65 psig).
8. Systems should not be overcharged, to avoid liquid return to the compressor
9. HEAD PRESSURE CONTROL ALCO (FSY-42S)
The head pressure controller is factory set to suit the refrigerant. It may be necessary to adjust this to
suit site conditions, to raise or lower the nominal head pressure.
ALCO (FSY-42S)
a. With the system switched off, connect a high pressure gauge to the liquid line service valve.
b. Switch on the system, and run for a few minutes to stabilise.
c. The head pressure should be approximately:
Min fan speed (0 rpm) and fan cut in pressure 200 psig (13.8 barg) are factory set and not adjustable.
NOTE: The condenser fan may stop if the operating pressure drops below 200 psig (13.8 barg)
R407C: 270-280 psig (18.9-19.6barg) to achieve this remove sealing plug and insert 2mm or 5/64"
allen key into setting screw. Turn allen key clockwise (+) or counter clockwise (-) to readjust the
setting.
Do not turn setting screw more than 3 turns clockwise (+3). Use following table as a quick
guideline for setting:
Pressure changes per turn of adjusting screw:
Pressure change: 9.2 ... 21.2 bar:
Clockwise ~ +2,5 bar, counter clockwise ~ -2,5 bar
After adjustment, re-insert sealing plug and make sure that it is properly fitted. IP65 protection
requires firmly sealed plug
NOTES:
Tolerances for condensing temperatures setpoint: ±2K

R407C REFRIGERANT

18 55908039-06