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II.9.5 Protection from corrosion
Do not use corrosive water containing deposits or debris. hereinafter the
corrosive limits for brazed stainless steel heat exchangers:
pH
7.5 ÷ 9.0
SO4--
< 70
HCO3-/SO4--
> 1.0
Total hardness
4.0 ÷ 8.5
CI-
< 50
PO43-
< 2.0
NH3
< 0.5
Fe+++
< 0.2
Mn++
< 0.05
CO2
< 5
H2S
< 50
Temperature
< 65
Oxygen content
< 0.1
Alkalinity (HCO3)
70 ÷ 300
Electrical Conductivity
10 ÷ 500
Nitrate (NO3)
< 100
If you are not reasonably sure of the water quality in the table above or
if there are doubts concerning the presence of different materials which
could corrode the heat exchanger over time, it is always advisable to insert
an intermediate heat exchanger which can be inspected, made of materi-
als that are able to resist these substances.
II.9.6 Protecting the unit from frost
II.9.6.1 Indications for unit when not running
IMPORTANT!
If the unit is not used during the winter period, the water contained in
the system may freeze.
IMPORTANT!
When the unit is out of service, drain all the water from the circuit.
The entire circuit must be drained in good time, a drainage point below
the water exchanger must be used to make sure all the water empties out.
Moreover, use the valves placed in the lower part of the water exchanger
so that is empties completely.
If the draining operation is felt to be too much trouble, ethylene glycol
may be mixed with the water in suitable proportions in order to guarantee
protection from freezing.
Units are available with an antifreeze heater (PA accessory) to keep the
evaporator intact, should the temperature drop excessively.
IMPORTANT!
The unit must not be isolated from the electrical power supply during
the entire seasonal stoppage
II.9.6.2 Indications for unit when running
When the unit is running, the control board protects the water side heat
exchanger from freezing by triggering the antifreeze alarm, which stops
the machine if the temperature of the sensor fitted on the heat exchanger
reaches the set point value.
The resistance of the water side primary and secondary heat exchanger
(RA-RDR accessory), the storage tank (RAS accessory) and the electric
pump unit (RAE-RAR accessory), prevents undesired effects due to freezing
during the operating breaks in winter (provided the unit remains powe-
red).
48
EQPI3X
ppm
ppm
The use of ethylene glycol is recommended if you do not wish to drain the
dH
water from the hydraulic system during the winter stoppage.
ppm
Table shows the multipliers which allow the changes in performance of
the units to be determined in proportion to the required percentage of
ppm
ethylene glycol.
ppm
The multipliers refer to the following conditions: condenser inlet air tempe-
ppm
rature 35°C; chilled water outlet temperature 7°C; temperature differential
at the evaporator and condenser 5°C.
ppm
For different functioning conditions, the same coefficients can be used as
ppm
their variations are negligible.
ppb
°C
ppm
ppm
µS/cm
Design air temperature in °C
ppm
% glycol in weight
Freezing temperature in °C
fc G
fc ∆pw
fc QF
fc P
fc G
fc ∆pw
fc QF
fc P
IMPORTANT!
If the mains switch is opened, it cuts off the electricity supply to the
storage tank plate exchanger heater, the antifreeze heater of the sto-
rage tank and the pump (RA, RDR, RAE, RAR, RAS accessories) and the
compressor crankcase heater. The switch should only be disconnected
for cleaning, maintenance or repair of the machine.
IMPORTANT!
Mixing the water with glycol modifies the performance of the unit.
2
0
10
15
-5
-7
1,025
1,039
1,085
1,128
0,975
0,967
0,993
0,991
Correction factor of the evaporatot glycol water flow
Correction factor of the evaporator pressure drops
Cooling capacity correction factor
Correction factor for the total absorbed electrical current
-3
-6
-10
-15
-20
20
25
30
35
40
-10
-13
-16
-20
-25
1,054
1,072
1,093
1,116 1,140
1,191
1,255
1,319
1,383 1,468
0,963
0,956
0,948
0,944 0,937
0,990
0,988
0,986
0,983 0,981
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