Johnson AURUM R290 M Serie Guide D'utilisation page 78

CAUTION
In the event of power failure, the above
features would fail to protect the unit from
freezing. Therefore, always keep the unit
powered on.
If the power supply for the unit is to be
switched off for a long time, the water in the
system pipe needs to be drained to avoid
damage to the unit and pipeline system due to
freezing.
5.6.2 Protected by glycol
Glycol lowers the freezing point of water.
CAUTION
Ethylene glycol and propylene glycol are toxic.
CAUTION
Glycol can corrode the system. When
uninhibited glycol comes into contact with
oxygen, it becomes acidic. This corrosion
process is accelerated by copper and high
temperature. The acidic uninhibited glycol
attacks metal surfaces, forming galvanic
corrosion cells that can cause severe
damage to the system. Therefore, it is
important to follow these steps:
Let a qualified specialist treat the water
correctly;
Select a glycol with corrosion inhibitors to
counteract acids formed by the oxidation of
glycols;
Do not use any automotive glycol
because its corrosion inhibitors have a
limited lifetime and contain silicates which
can contaminate or block the system;
Do not use galvanized pipes in glycol
systems as such pipes may lead to the
precipitation of certain components in the
glycol's corrosion inhibitor.
NOTE
Glycol absorbs moisture
environment, so it is important to avoid using
glycol exposed to air. If glycol if left
uncovered, the water content increases,
lowering the glycol concentration and
potentially causing hydraulic components to
freeze. To prevent this, take precautions
and minimize glycol's exposure to air.
Types of glycol
The types of glycol that can be used depend on
whether the system contains a domestic hot water
tank:
If
The system contains a
domestic hot water
tank
The system does NOT
contain a domestic hot
water tank
(a) Propylene glycol, including the necessary
inhibitors, falls in Category III according to EN1717.
Required concentration of glycol
The required concentration of glycol depends on the
lowest expected outdoor temperature, and on
whether you want to protect the system from bursting
or from freezing. To prevent the system from
freezing, more glycol is required.
Add glycol according to the table below.
Lowest expected
outdoor temperature
[ 1 ]
but cannot prevent the liquid inside the piping from
freezing.
[ 2 ]
from freezing.
from the
21
Then
Only use propylene
glycol (a)
Either propylene
glycol(a) or ethylene
glycol can be used
Prevention
from bursting
–5 °C 10 %
–10 °C 15 %
–15 °C 20 %
–20 °C 25 %
–25 °C 30 %
–30 °C 35 %
: Glycol can prevent the piping from bursting,
: Glycol can prevent the liquid inside the piping
NOTE
The required concentration might vary
depending on the type of glycol used.
ALWAYS compare the requirements from the
table above with the specifications provided by
the glycol manufacturer. If necessary, meet the
requirements set by the glycol manufacturer.
The added concentration of glycol should
NEVER exceed 35 %.
If the liquid in the system is frozen, the
pump will NOT be able to start. Please note
that solely preventing the system from
bursting may not prevent the liquid inside
from freezing.
If water remains stagnant within the
system, it is highly likely to freeze and result in
system damage.
[ 1 ] Prevention [ 2 ]
from freezing
15 %
25 %
35 %
N/A
N/A
N/A
V.1