Hitachi YUTAKI M RASM-3WF2E Installation And Operation Manual page 28

5.3.5 Anti-freezing protection for water circuit
◆ Anti-freezing protection
Frost can damage the system. To prevent components from freezing, software has been designed
with special frost protection functions, that include the activation of pump & heater in case of low
temperatures (see Service Manual Water pump control).
In case of a power supply failure, functions above cannot guarantee protection, allowing freezing
and possible breakage of pipes and / or components. Due to that, an anti-freezing system
(independent of power supply) is required:
• Adding glycol into the water circuit to lower the freezing point of water.
• Adding anti-freeze valves (field supplied)
!
CAUTION
Both methods cannot be used simultaneously since glycol can leak out from valves to environment.
5.3.6 Glycol as anti-freezing protection
Adding glycol into the water circuit to lower the freezing point of water.
For YUTAKI systems, 2 types of glycols can be used: ethylene glycol & propylene glycol.
• Ethylene glycol is toxic. Consequently, its use is forbidden in systems that includes a domestic
hot water tank.
• Propylene glycol (including necessary inhibitors, classified as Category III acc. To EN 1717) can
be used in all systems.
Required concentration depends on:
• The lowest expected outdoor temperature.
• Protection against bursting or freezing.
PMEN0657 rev.0 - 02/2024
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