Protecting The Unit From Frost - Hitecsa EQP1X 117 Manual De Instalación, Uso Y Mantenimiento

II.5.3.2 Recommended installation
Models 117÷130
A
Main
B
Recovery (secondary)
1
Valve
2
Water filter
3
Main system water inlet
4
Main system water outlet
5
Recovery water inlet
6
Recovery water outlet
IOM_EQP1X_117a133_208094_200901_ES-EN-FR-DE-IT
1
1
1
1
2
1
1
2
SECTION II: INSTALLATION AND MAINTENANCE
II.5.4

PROTECTING THE UNIT FROM FROST

IMPORTANT!
If the mains switch is opened, it cuts off the
electricity supply to the plate exchanger heater and
the storage tank antifreeze heater (if included). The
switch should only be disconnected for cleaning,
maintenance or repair of the machine.
When the unit is running, the control board protects the water-side heat
exchanger from freezing by making the antifreeze alarm cut in, stopping
the machine if the temperature of the sensor fitted on the heat
exchanger reaches the set point value.
IMPORTANT!
When the unit is out of service, drain all the water
contents from the circuit.
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.
IMPORTANT!
Mixing the water with glycol modifies the
performance of the unit.
The use of ethylene glycol is recommended if you do not wish to drain
the water from the hydraulic system during the winter stoppage, or if the
unit has to supply chilled water at temperatures lower than 5°C The
addition of glycol changes the physical properties of the water and
consequently the performance of the unit. The proper percentage of
glycol to be added to the system can be obtained from the most
demanding operating conditions from those shown below.
Table "H" shows the multipliers which allow the changes in performance
of the units to be determined in proportion to the required percentage of
ethylene glycol.
The multipliers refer to the following conditions: condenser inlet air
temperature 35°C; chilled water outlet temperature 7°C; temperature
differential at evaporator 5°C.
For different operating conditions, the same coefficients can be used as
their variations are negligible.
Table "H"
% glycol in
10 %
weight
Freezing
temperature °C
fc QF 0,991
fc P 0,996
fc ∆pw
1,053
fc G 1,008 1,028 1,051 1,074 1,100
fc QF = Cooling capacity correction factor.
fc P= Correction factor for the absorbed electrical current.
fc ∆pw = Correction factor of the pressure drops in the evaporator
fc G = Correction factor of the glycol water flow to the evaporator
55
15 % 20 % 25 %
-5 -7 -10 -13
0,987 0,982 0,978
0,995 0,993 0,991
1,105 1,184 1,237
30 %
-16
0,974
0,989
1,316