Hitachi YUTAKI S COMBI Series Installation And Operation Manual page 68

7.1.0.5 Drain pipes connection
For a correct drainage, connect the drain pipe for the safety valve (located at the top rear side of
the unit) to the general draining system.

NOTE
• The safety valve is activated when water pressure reaches 3 bars.
• Drain taps must be provided at all low points of the installation to permit complete drainage of
the circuit during servicing.
• P&T relief valve is activated when water pressure reaches 7 bar and/or water temperature
reaches 96°C
• Discharge pipe must be made of metal or any other material capable to withstand the high
pressure and high temperature from the P&T relief valve.
• For a correct installation and workpipe of the discharge pipe on UK market models, refer to UK
Building Requirements
7.1.1 Test and check
Finally, test and check the following items:
• Water leakage
• Refrigerant leakage
• Electrical connection
• ...

NOTE
Please refer to the chapters of
"Commissioning" in this document and refer the Outdoor unit Installation and Operation manual
for the specific details about refrigerant charge tasks.
!
DANGER
Do not connect the power supply to the indoor unit prior to filling the space heating circuit (and
DHW circuit if it were the case) with water and checking water pressure and the total absence of
any water leakage.
PMEN0645 rev.0 - 04/2023
P&T relief valve
(Only for UK market)
"5.2.3 Refrigerant charge",
Safety valve
"5.3.2.1 Water filling" and
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