Marstair 526 HL Series, Technical Manual

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EVACUATING
Connect a vacuum pump to the service ports on the outdoor unit valves and evacuate the interconnecting pipework and
indoor unit to 1000 microns (1 Torr) or better and allow to be held for a minimum of 15 minutes.
After evacuating the indoor unit and interconnecting pipework, open the outdoor unit valves using a 5mm Allen key. The high
and low side pressures should equalise within a minute.
Run the system for a few minutes to allow it to stabilize.
If a manual HP cutout is fitted, ensure that the reset button is depressed (in the compressor compartment, outdoor unit).
MHPUE units: if no extra refrigerant is to be added REMOVE link JP6 (in the electrics box, outdoor unit, identified by a white
label), otherwise the unit will always run at full speed .
ADDING REFRIGERANT
Each outdoor unit is charged with refrigerant, as below:-
MCU(+)90 MCU(+) 100 MCU(+) 130 MCU(+) 165 MHPUE 90 MHPUE 100 MHPUE 130
FACTORY CHARGE (g)
(sufficient for up to 7.5m
runs at UK conditions)
R407C 2060 2520 4170 4540 2260 3380 4470
R22 1960 2400 3970 4320 2330 3490 4610
1. Ensure the refrigerant being added is the same refrigerant that the system was originally charged with.
2. Refrigerant should be introduced with the system in the AIR CONDITIONING MODE (including heat pumps).
3. Refrigerant should be charged through the Schrader valve on the indoor unit, or the service port on the suction
service valve on the outdoor unit.
4. Indoor and outdoor units should be run at maximum fan speed during charging:
Set the indoor unit to operate in cooling mode at maximum speed.
MHPUE are supplied with link JP6 fitted on the outdoor unit pcba; this is only for charging, overriding alarms
and running the MHPUE fan at maximum speed during the charging process.
(Do not forget to remove it once charging is complete: see 10)
MCU+ outdoor units are fitted with head pressure control; before charging, isolate the unit and transfer the
blue wire on the head pressure control from terminal 4 to terminal 1.
(Do not forget to transfer it back once charging is complete: see 10)
5. All systems with pipe runs longer than 7.5m (UK or NEMA) require added refrigerant.
As a guide, add:-
1/2" Expansion line add 30 g/m; 5/8" Expansion line add 48 g/m.
6. Further refrigerant needs to be added if the system is to be run at NEMA conditions (27°C/19°C indoor, 35°C
ambient) :-
MCU(+)90 MCU(+) 100 MCU(+) 130 MCU(+) 165 MHPUE 90 MHPUE 100 MHPUE 130
Extra refrigerant required
for NEMA conditions (g) R407C 115 145 250 200 180 250 200
R22 110 140 240 190 190 260 210
7. Run the system for a few minutes to allow it to stabilize.
8. If a sight glass is fitted, it should be just clear of bubbles (flooded).
9. Indications of incorrect charge are:-
Undercharged unit: The top few tubes of the evaporator are dry and there are (possibly) slight signs of
frosting at the inlet to the evaporator coil.
Overcharged unit: The suction line 'sweats' all the way back to the compressor.
10. MHPUE units: once refrigerant has been added, REMOVE link JP6 (in the electrics box, outdoor unit, identified by a
white label), otherwise the unit will always run at full speed .
MCU(+) units: once refrigerant has been added, transfer the blue wire on the head pressure control back
from terminal 1 to terminal 4.
11. MHPUE units: 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 incorporating MHPUE units, or MCU(+) units fitted with a
3 minute timer kit.