16
SECTION II: INSTALLATION AND MAINTENANCE
II.6.4.2
Indications for unit when operating
In this case, it is the microprocessor control board which protects the
evaporator from freezing. When the set temperature has been reached,
the antifreeze alarm is triggered stopping the unit, while the pump
keeps running normally.
The use of ethylene glycol is recommended if you do not wish to drain
the water from the hydraulic system during the winter break or if the unit
must supply chilled water at temperatures lower than 5°C (the latter
case is not considered here and depends on the size of the unit
system).
Table “
H
” indicates the multipliers that allow the unit performance
changes 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 temperature 7°C; temperature
differential at evaporator 5°C.
For different operating conditions, the same coefficients can be used as
their variations are negligible.
IMPORTANT!
Mixing the water with glycol modifies the
performance of the unit.
Use of anti-freeze solutions with BT accessory
The table indicates the ethylene/propylene glycol percentages to be
used in units with the BT accessory based on the produced chilled
water temperature. Contact pre-sales service for information regarding
performance of the units.
From -3°C to -8°C
30%
From 0°C to -2°C
20%
From 4°C to 1°C
10%
Table “H”
Minimum outdoor air temperature °C
2
0
-3
-6
-10
-15
-20
% glycol in weight
10
15
20
25
30
35
40
Freezing temperature in °C
-5
-7
-10
-13
-16
-20
-25
fc G
1,025
1,039
1,054
1,072
1,093
1,116
1,14
fc ∆pw
1,085
1,128
1,191
1,255
1,319
1,383
1,468
fc QF
0,975
0,967
0,963
0,956
0,948
0,944
0,937
fc P
0,993
0,991
0,99
0,988
0,986
0,983
0,981
fc QF
= Cooling capacity correction factor.
fc P
= Correction factor for the total 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.
II.6.5
Heat recovery system
II.6.5.1
Operation
To recover the heat from the compressor and consequently produce hot
water, the differential pressure switch (PD) must give its consent to the
electronic board; to achieve this result, the circulating pump (P) must be
active and the water must circulate normally in the recovery exchanger.
The electronic board also controls the recovery unit and/or
desuperheater (ST8) outlet temperature so as to guarantee the
maximum outlet temperature.
II.6.5.2
Installation precautions
DANGER!
The recovery unit / desuperheater is set directly in
series with the compressors; therefore, the internal
temperature of the recovery exchanger can reach
120°C at a pressure of 2 bar, in particular faulty
conditions. This could lead to the formation of
steam from overheated water.
Minimum % glycol in
weight
Evaporator glycol
water outlet temperature
Summary of Contents for EQU-PF 2100
Page 60: ...NOTE...
