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This value will allow the definition of the following limits:
1.
Evaporator frost protection
2.
Low pressure protection
It is recommended that the commissioning of a brine system
is done by Carrier.
For information: The protection values given by our supplier,
based on the antifreeze solutions used in the Carrier
Montluel laboratory, are as follows: (these values can change
for different suppliers).
% by weight, glycol
freeze point, °C
ethylene glycol
10
-3.8
15
-6.1
20
-8.8
25
-11.8
30
-15.2
35
-19.1
40
-23.6
45
-29
Based on the table above, if the ethylene glycol concentration
by weight in the water loop is 35% the value of -19.1°C must
be used in the software.
It is essential to carry out an annual check (minimum) of
the amount of glycol, and adjust the frost protection value
in the software based on the rate measured. This procedure
must be systematic, if water or antifreeze solution is added.
The curve below shows the minimum frost protection
temperature that must be observed, based on the leaving
water temperature.
Minimum frost protection temperature
0
-5
-10
-15
-20
-25
-30
-16
-14
-12
Evaporator leaving water temperature, °C
NOTEs:
•
for unit frost protection at low air temperature, the
brine percentage must be evaluated.
•
The maximum glycol rate for units with hydronic kit
(options 116) is 45%.
•
The temperature of -15°C brine can only be obtained
with ethylene glycol at 45%.
•
The maximum recommended temperature difference
is 5 K.
ImpOrTANT: for glycol concentrations below 20% a
corrosion inhibitor suitable for the application must be
used to avoid corrosion due to the agressive nature of brine.
freeze point, °C
propylene glycol
-2.6
-4.3
-6.6
-9.6
-13
-16.7
-20.7
-25.3
-10
-8
-6
-4
The presence of glycol reduces the life of the pump fittings.
It is recommended to change the fittings or the pump:
•
every 40 000 hours for applications with water,
•
every 15 000 hours for applications with glycol
concentrations above 30%.
To facilitate maintenance operations, it is recommended
to install shut-off valves upstream and downstream of the
unit.
20 - STaNDaRD MaINTENaNCE
Air conditioning equipment must be maintained by profes-
sional technicians, whilst routine checks can be carried out
locally by specialised technicians.
All refrigerant charging, removal and draining operations
must be carried out by a qualified technician and with the
correct material for the unit. Any inappropriate handling
can lead to uncontrolled fluid or pressure leaks.
WArNINg: Before doing any work on the machine ensure
that the power is switched off. If a refrigerant circuit is
opened, it must be evacuated, recharged and tested for
leaks. Before any operation on a refrigerant circuit, it is
necessary to remove the complete refrigerant charge from
the unit with a refrigerant charge recovery group.
simple preventive maintenance will allow you to get the
best performance from your hvaC unit:
•
improved cooling performance
•
reduced power consumption
•
prevention of accidental component failure
•
prevention of major time-consuming and costly
interventions
•
protection of the environment
There are five maintenance levels for HVAC units, as
defined by the AFNOR X60-010 standard.
20.1 - level 1 maintenance
see note in chapter 20.3.
Simple procedures, can be carried out by the user on a
weekly basis:
•
Visual inspection for oil traces (sign of a refrigerant leak),
-2
0
•
Air heat exchanger (condenser) cleaning - see chapter
'Air heat exchanger - level 1',
•
Check for removed protection devices, and badly
closed doors/covers,
•
Check the unit alarm report when the unit does not work
(see the 30RB/30RQ 017-160 Pro-Dialog+ control
manual),
•
General visual inspection for any signs of deterioration,
•
Verify the charge in the sight-glass,
•
Check that the water temperature difference between
the heat exchanger inlet and outlet is correct.
43
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