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WATER CONNECTIONS AND WATER CHARACTERISTICS
For all the water connections (with the exception of the conden-
sate drain), the following are recommended:
- flexible connections to avoid transmitting vibrations and allow
small movements of the air-conditioner;
- joints in three pieces, near the fittings, to simplify the removal of
the unit;
- on-off valves to disconnect the unit from the water circuit:
where possible use ball valves with full opening to minimise
pressure drop.
(For AW-AT-AF models) check that the cross-section of the
chilled water pipes and the characteristics of the circulating pump
are suitable: an insufficient water flow-rate affects the perfor-
mance of the air-conditioner.
Make sure that the water contained in the water circuit meets the
following requirements throughout the entire life of the system:
ref.
Description
1
hydrogen ion concentration
2
calcium (Ca) and magnesium (Mg) content
3
chloride ions
4
iron ions
5
manganese ions
6
carbon dioxide
7
hydrogen sulphide
8
oxygen
9
chlorine
10
ammonia
11
carbonate-sulphate ratio
where: 1/1.78 °D=1 °Fr con 1°Fr= 10 gr CaCO
ppm = parts per million; ppb = parts per billion
Explanations
ref. 1:
a hydrogen ion concentration (pH) greater than 9 implies
a high risk of fouling, while a pH less than 7 implies a high
risk of corrosion
ref. 2:
hardness refers to the quantity of Ca and Mg carbonate
dissolved in the water at a temperature below 100 °C
CONNECTION TO BRAZED PLATE CONDENSER AW-AT -AF
AW-AT -AF water-cooled units
The condenser must be connected to the cooling water circuit,
making sure that the water inlet and outlet connections are cor-
rect.
If the water temperature falls below the dew point of the condi-
tioned air, insulate the pipes with closed cell material (e.g.:
Armaflex or equivalent) to prevent condensation; the insulation
CORRECTION FACTORS
ETHYLENE GLYCOLE
A mix of water plus glycole used has fluid instead of only water cause a cooling capacity reduction of the unit.
Multiplay the cooling capacity for the values reported of the following tables
Iceing temperature
% of glycole on tot. charge
Flow factor
P. drops factor
INCROSTATION FACTOR
All datas reported are refered to a complete clean brazed blade condenser (incrostation factor = 1).
For different values of incrostation factor multiplay all datas reported on cooling capacity tables for factors reported on following table.
Incrostation factor
Incrostation factor
Compressor factor
Total power factor
32
EN
Symbol
Values
pH
7.5÷9
Hardness
4÷8.5 °D
-
Cl
< 150 ppm
Fe
3+
< 0.5 ppm
Mn
2+
< 0.05 ppm
CO
< 10 ppm
2
H
S
< 50 ppb
2
O
< 0.1 ppm
2
Cl
< 0.5 ppm
2
NH
< 0.5 ppm
3
2-
HCO
/ SO
> 1
3-
4
/ m
3
3
0
0
cQ
1
cdp
1
(m
2
°C/W)
f1
fk1
fx1
Check that the water inlet and outlet connections are correct.
Insulate all the chilled water pipes with closed cell material (e.g.:
Armaflex or equivalent), to prevent condensation; the insulation
must allow access to the valves and the three-piece joints.
(For AW-AT-AFmodels) check that the water circuit has been
filled with an antifreeze mixture containing the right percentage of
ethylene glycol.
To select the pipeline refer to "Pressure Drops on stain-
less steel pipes"
(temporary hardness). High hardness implies a high risk of
fouling.
ref. 3:
a chloride ion concentration higher than the value indi-
cated will lead to corrosion
ref. 4-5-8: e presence of iron, manganese and oxygen irons will
give rise to corrosion
ref. 6-7:
carbon dioxide and hydrogen sulphide are impurities
that lead to corrosion occurring more readily
ref. 9:
the typical value in mains water is between 0.2 and 0.3
ppm. High values will cause corrosion
ref. 10:
the presence of ammonia boosts the oxidation capacity of
oxygen
ref. 11:
at levels below the value shown in table, there is the
risk of corrosion due to galvanic current running
between the copper and the other less noble metals.
In the presence of ethylene glycol (toxic), corrosive compounds
will form over time, and therefore inhibitors need to be added.
When the water is dirty and/or aggressive, an intermediate heat
exchanger must be installed upstream of the heat exchangers on
the chiller assembly.
must allow access to the valves and the three-piece joints.
Seal the holes where the pipes pass through the base of the air-
conditioner to avoid the bypass of air.
N.B.: the water system of the unit is PN16
-5
-10
-15
12%
20%
28%
1,02
1,04
1,075
1,07
1,11
1,18
4,4 x10-5
0,86x10-4
---
0,96
---
0,99
---
0,99
ACCURATE AX - AW - AD - AT - AF
-20
-25
35%
40%
1,11
1,14
1,22
1,24
1,72x10-4
0,93
0,98
0,98
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