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OMNIA M 3.2
9.4.4 Water circuit anti-freeze protection
Ice formation can cause damage to the hydraulic system. As
the outdoor unit may be exposed to sub-zero temperatures,
care must be taken to prevent freezing of the system.
All internal hydronic parts are insulated to reduce heat loss.
Insulation must also be added to the field piping.
The software contains special functions using the heat
pump to protect the entire system against freezing. When
the temperature of the water flow in the system drops to a
certain value, the unit will heat the water, either using the
heat pump, the electric heating tap, or the backup heater.
The freeze protection function will turn off only when the
temperature increases to a certain value.
In event of a power failure, the above features would not
protect the unit from freezing.
Do one of the following to protect the water circuit against
freezing:
Add glycol to the water. Glycol lowers the freezing point
of the water.
Install freeze protection valves. Freeze protection valves
drain the water from the system before it can freeze.
NOTE
If you add glycol to the water, do NOT install freeze
protection valves. Possible consequence: Glycol leaking
out of the freeze protection valves.
1. Freeze protection by glycol
About freeze protection by glycol
Adding glycol to the water lowers the freezing point of water.
WARNING
Ethylene glycol is toxic.
Ethylene Glycol
Quality of glycol
Cooling capacity
modification
0%
1.000
10%
0.984
20%
0.973
30%
0.965
Propylene Glycol
Quality of glycol
Cooling capacity
modification
0%
1.000
10%
0.976
20%
0.961
30%
0.948
22T÷30T
Modification coefficient
Power modification
1.000
0.998
0.995
0.992
Modification coefficient
Power modification
1.000
0.996
0.992
0.988
Cod. 3QE47660 - Rev. 00 - 02/2022
WARNING
Due to the presence of glycol, corrosion of the system
is possible. Uninhibited glycol will turn acidic under the
influence of oxygen. This process is accelerated by the
presence of copper and high temperatures. The acidic
uninhibited glycol attacks metal surfaces and forms
galvanic corrosion cells that cause severe damage to
the system. Therefore it is important that:
the water treatment is correctly executed by a qualified
water specialist,
a glycol with corrosion inhibitors is selected to
counteract acids formed by the oxidation of glycols,
no automotive glycol is used because their corrosion
inhibitors have a limited lifetime and contain silicates
which can foul or plug the system,
galvanized pipes are NOT used in glycol systems
since the presence may lead to the precipitation of
certain components in the glycol's corrosion inhibitor.
NOTE
Glycol absorbs water from its environment. Therefore do
NOT add glycol that has been exposed to air. Leaving
the cap off the glycol container causes the concentration
of water to increase. The glycol concentration is
then lower than assumed. As a result, the hydraulic
components might freeze up after all. Take preventive
actions to ensure a minimal exposure of the glycol 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, then
only use propylene glycol*;
If the system does NOT contain a domestic hot water
tank, then you can use either propylene glycol* or ethylene
glycol;
*Propylene glycol, including the necessary inhibitors, classified as
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:
Water flow
Water resistance
modification
1.000
1.000
1.118
1.019
1.268
1.051
1.482
1.092
Water flow
Water resistance
modification
1.000
1.000
1.071
1.000
1.189
1.016
1.380
1.034
Minimum outdoor
temperature
0°C
-5°C
-15°C
-25°C
Minimum outdoor
temperature
0°C
-4°C
-12°C
-20°C
111
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