GEA Searle NSQ Series, Installation And Maintenance Instructions Manual

5

ISOLATED BEFORE MAINTENANCE WORK IS 
UNDERTAKEN 

Oil Charge 
The compressors are pre charged with Polyolester oil. 
Following initial start-up, some of this oil will migrate to 
other areas of the system. Ensure the oil charge in the 
system is adequate as follows :-  

 
The following routine maintenance is required: 
Every 3-6 months 
The condenser should be cleaned with a soft brush to 
ensure correct operation of the condensing unit. When the 
condenser coil is obstructed by dirt or rubbish, the unit will 
experience high condensing temperatures which will result in 
higher running costs, loss of compressor efficiency and 
ultimately overheating of the compressor and/or condenser 
fans. 

• 

N2CQ ‘M’ models utilise an oil balance line between 
compressors, ensure the oil balance line sightglass 
level is 1/2 full when the compressors are not running. 

• 

N2CQ ‘L’ models are fitted with a separator reservoir, 
ensure the oil charge is adequate to show in the upper 
sight glass when the compressors are not running. 

The pressure relief valve should be inspected for any 
pressure release. If a release has occurred or there is a 
requirement by the customer maintenance schedule the 
relief valve should be changed. 

Note: on N2CQ ‘M’ models with oil balance lines, the oil 
level may show as empty when only one compressor is 
running, this is normal. The true oil level will show when 
both compressors are running, or both are at rest. 

The PRV MUST be changed every 5 years. 

Only suitable Polyolester oil, such as Mobil EAL  

Arctic 22 CC (or equivalent), should be used. 

Every 12 months 

Check security of fixings, especially the fan and motor 
mounting. Check refrigerant pipeline for damage and leaks.
Check motor (fans should rotate freely). 

4. OPERATING LIMITS 
The HP/LP switch must be set to prevent the unit from 
operating outside of its application limits. 

Check torque settings of compressor rotalock valves (see 
table below). 

The LP switch and Step Controller must not be set any 
lower than the figures below: 

When necessary 

R404A & R407C 

Clean the fins, guard and general casework. Care must be 
taken when cleaning the fins to prevent damage. It is 
recommended that a soft brush and mild detergent solution 
be used. 

Maximum HP 

Cut out BarG

Minimum 

SST °C     

R404A 
R407C 

LP Cut out 

BarG 

R407C 

Unit 

Range 

LP Cut out 

BarG R404A 

R404A 
R407C 

High-pressure spray washing of the unit must not be 
undertaken, as damage to fin coatings and components will 
occur. Low-pressure spray washing using specialist coil 
cleaning solutions is recommended. 

NS/NC-

'MX/S' 

-20 2  1.7 

25.2 

NS/NC-
'LX/S/V' 

-40 0.35  N/A 25.2 

WARNING! SAFETY GOGGLES MUST BE WORN 
DURING THIS OPERATION. 

SCQ 'M' 

-15 

2.7 

N/A 

25.2 

SCQ 'LX' 

-35 

0.7 

N/A 

25.2 

6. INVALIDATION OF GUARANTEE 

Searle accepts no liability, according to Searle's terms and 
conditions of sale, for loss or damage arising as a result of: 

R134A 

Maximum HP Cut 

out BarG 

Minimum SST 

°C          

R134a 

LP Cut out BarG 

R134a 

Unit Range 

R134a 

(i)   Failure to install, set up or put to work any part of 

equipment in the manner specified in the I&M 
instructions, or 

'MX/S' -20 

0.37 

14.4 

(ii) 

 Failure to maintain the equipment in the manner 

specified in the I&M instructions, or 

'LX/S/V' -20 

0.37 

14.4 

SCQ 

Not Suitable for use with R134a 

(iii) 

 Replacement parts, additional parts or accessories 

supplied by persons other than Searle having been 
incorporated into, or attached to the equipment, or 

The LP differential setting must be set high enough to 
prevent short cycling of the unit. 

(iv)  The equipment having been adapted for use, operated 

or used in such a way as does not conform to Searle's 
recommendations. 

The LP Cut-Out pressure is the LP range setting minus 
the LP differential setting. 

The HP switch must be set at 0.9 x the PRV setting for all 
refrigerants. As standard units are fitted with a PRV set to 
27.6 BarG, the HP switch must not be set higher than 
25.2 BarG. 

7. Compressor Rotalock Valve Torques 

Discharge Suction 

Unit 

Size Torque  Size  Torque 

For R134a refrigerant a lower pressure 16 BarG PRV is 
available, part number 200-200-528, the HP switch must 
not be set any higher than 14.4 BarG. 

SCQ7L & 8L 

N/A 

N/A 

1" x 14 

60 -70 Nm 

SCQ13M to 27M 

Multiple Evaporator Applications 

SCQ9L & 14L 

If the condensing unit is connected to multiple 
evaporators operating independently of one another, it is 
essential that the saturated suction temperature remains 
within the operating limits when the minimum number of 
evaporators are running.  

1" x 14 

60 - 70 Nm 

1" x 14 

60 - 70 Nm 

SCQ31M 

NSQ09L to 18L 

60 – 70 

90 – 100 

1" x 14 

1 1/4" x 12 

Nm 

Nm 

NSQ15M to 45M 

If the saturated suction temperature falls close to or below 
the operating limits for medium temperature 'M' units 
when the minimum number of evaporators are running, 
the use of 'L’ units, or other Searle condensing unit 
products should be considered. 

NSQ24L to 40L 

90 – 100 

 100 – 120 

1 1/4" x 12 

1 3/4" x 12 

Nm 

Nm 

NSQ56M to 92M 

NSQ48L 

100 – 120 

 140 – 145 

 1 3/4" x 12

 2 1/4" x 12 

Nm 

Nm  

NSQ110M 

 
5. MAINTENANCE 

Check compressor rotalocks as described in the 
maintenance section ‘Every 12 months’ (p4). 

 
WARNING! THE UNIT MUST BE ELECTRICALLY 

Note:  

connection sizes are the threaded spud connection