emmeti EC Serie Manual De Instalacion Y Uso página 37

II.6.4 RECOMMENDED INSTALLATION
EC-EH 0510÷0710
4
3
5
6
EC-EH 0910÷1110
4
3
5
6
EC-EH 1510÷3010
4
3
1
1
Valve
2
Water filter (supplied)
3
Water inlet
4
Water outlet
5
Charge/drain coupling
6
Charge/drain tap
7
System water pressure gauge
1
7
1
2
1
7
1
2
1
1
2
SECTION II: INSTALLATION AND MAINTENANCE
II.6.5 PROTECTING THE UNIT FROM FROST
IMPORTANT!
If open, the mains switch cuts off the power supply
to the plate exchanger electric heater and the
compressor crankcase heater (for models EH
1110T÷3010T). This switch should be operated only
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 probe 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 that 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 outlet water 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 by weight
Freezing
temperature °C
fc QF
fc P
fc Δpw
fc G
fc QF = Cooling capacity correction factor.
fc P = Correction factor for the absorbed electrical current.
fc Δpw = Correction factor of the pressure drops in the evaporator
fc G = Correction factor of the glycol water flow to the evaporator
37
10 % 15 % 20 % 25 %
-5 -7 -10
0,991 0,987 0,982 0,978
0,996 0,995 0,993 0,991
1,053 1,105 1,184 1,237
1,008 1,028 1,051 1,074
30 %
-13 -16
0,974
0,989
1,316
1,100