28
Piping work
Freeze protection
Freeze protection solutions must use propylene glycol with a toxicity rating of Class 1 as listed in Clinical Toxicology of
Commercial Products, 5th Edition.
t
Ethylene glycol is toxic and must not be used in the primary water circuit in case of any cross-contamination of
the potable circuit.
WARNING
Freezing Points of Propylene Glycol - Water Mixtures
Percent Propylene Glycol [wt. %]
Freezing Point [ °F ]
Freezing Point [ °C ]
0
32
0
10
26
-3
20
20
-7
30
10
-12
36
0
-18
40
-5
-20
43
-10
-23
48
-20
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Setting capacity and pre-pressure of the expansion vessel
When it is required to change the default pre-pressure of
the expansion vessel(1 bar), keep in mind the following
guidelines:
f
Use only dry nitrogen to set the expansion vessel pre-
pressure.
f
Inappropriate setting of the expansion vessel
pre-pressure will lead to malfunction of the system.
Therefore, the pre-pressure should only be adjusted by a
licensed installer.
2.5
2.0
1.5
1.0
0.5
0.0
150
200
250
300
350
Total water volume(ℓ)
Pr
e-pr
essur
e(bar)
Operation range
Installation height
difference(a)
Water volume
< 220 Litres
> 220 Litres
<7m
No pre-pressure adjustment required.
Actions required:
t
Pre-pressure must be decreased, calculate
according to “Calculating the pre-pressure of
the expansion vessel”.
t
Check if the water volume is lower than
maximum allowed water volume.
>7m
Actions required:
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Pre-pressure must be increased, calculate the
appropriate value following by “Calculating
the pre-pressure of the expansion vessel”.
t
Check if the water volume is lower than
maximum allowed water volume.
Expansion vessel of the unit too small for the
installation.
(a) Installation height difference: height difference(m) between the highest point of the water circuit and the indoor unit. If
the unit is located at the highest point of the installation, the installation height is considered 0m.
t
When Expansion vessel has a capacity 8 liters and 1bar pre-charged.
Water volume of total system for reliable performance is minimum 30 Liter(AE050RX****), 50 Liter(AE120/160RX****).
