49
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
Freeze point, °C
propylene glycol
10
-3.8
-2.6
15
-6.1
-4.3
20
-8.8
-6.6
25
-11.8
-9.6
30
-15.2
-13
35
-19.1
-16.7
40
-23.6
-20.7
45
-29
-25.3
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
-30
-25
-20
-15
-10
-5
0
-16
-14
-12
-10
-8
-6
-4
-2
0
Evaporator leaving water temperature, °C
Minimum fr
ost pr
otection temper
atur
e
, °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.
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. See the standard EN 378-
4.
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),
•
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 Touch Pilot Junior 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.
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