Hitachi YUTAKI M Bedienungsanleitung Seite 32

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CAUTION
• Do not add glycol that has been exposed to air as glycol absorbs water from the environment.
Final glycol concentration can be lower than expected, allowing system to freeze up.
• Corrosion, that can damage gravely the system, is possible when glycol is added. Uninhibited
glycol with oxygen can become acidic & attack metal surfaces, forming galvanic corrosion
cells. The responsible installer must be a qualified water specialist & should decide which anti-
freeze solution is necessary for each site's conditions. Corrosion inhibitors must be selected
to counteract acids formed by glycol oxidation. Inhibitors with limited lifetime or containing
silicates are forbidden. Galvanized pipes must be avoided since they can precipitate inhibitors.
When using inhibitors, always follow manufacturer's instructions and ensure that the product is
appropriate for materials used in water circuit.
• Adding glycol to water circuit reduces the maximum allowed water volume of the system and
also capacity. Additional info can be found on Technical Catalogue.
5.4.7 Insulation
Water circuit piping must be insulated to prevent condensation and to reduce heat loss.
For outdoor water piping, recommended insulation thickness depends on piping length.
Recommended thickness values for an insulation of ʎ=0.039W/mK are shown in table below.
Piping length (mm)
20 - 30
30 - 40
40 - 50
5.4.8 Water filling
1 Check that a water check valve (ATW-WCV-01 accessory) with a shut-off valve (field supplied)
is connected to the water filling point (water inlet connection) for filling the space heating
hydraulic circuit (see
2 Make sure all the valves are open (water inlet/outlet shut-off valves and the rest of valves of the
space heating installation components).
3 Ensure that the air purgers of the unit and installation work correctly.
4 Connect a drain pipe to the safety valve and make sure that it is correctly connected to the
general draining system. The safety valve is later used as an air purging device during the water
filling procedure.
5 Fill the space heating circuit with water until the pressure displayed on the manometer reaches
approximately 1.8 bar.

NOTE
While the system is being filled with water, it is highly recommended to operate the safety valve
manually so as to help with the air purging procedure.
PMEN0647 rev.0 - 11/2023
< 20
"5.2 Outdoor Unit Draining
Minimum insulation thickness (mm)
19
32
40
50
Operation").
5
24