Hitachi YUTAKI S COMBI Serie Manual De Instrucciones página 27

REFRIGERANT AND WATER PIPING
The following accessories are necessary for the compliance of
the YUTAKI S COMBI for UK market with the UK requirements
referred in the UK Building Regulations 2000.
1 temperature and pressure relief valve (factory supplied),
•
fitted at the hottest part of the DHW tank. This device protects
the unit of excessive temperature (>96ºC) and excessive
pressure (>7 bar) in the DHW tank. Additionally, a Ø15
diameter pipe (factory supplied)is fitted to the outlet of the
relief valve and drives the discharge to the tundish (4).
• 1 Tundish(4)(field supplied), installed in a vertical position,
with no more than 600 mm of pipe between the valve outlet
and the tundish.
• 1 Tundish outlet pipe (2)(field supplied) with a vetical
section at least 300 mm long below the tundish(4), before
any elbows or bends in the pipework. This pipe should be
made of metal or other material that has been demonstrated
to be capable of safety withstanding temperatures and
pressure of the water discharged, as it is refferred in the UK
Building Regulations.
• The discharge pipe from the tundish (2) must terminate
in a safe place where is no risk to persons in the vicinity
of the discharge. The discharge will consist of high water
temperature and pressure.
4.4.5 Requirements and recommendations for
the hydraulic circuit
• The maximum piping length depends on the maximum
pressure availability in the water outlet pipe. Please check
the pump curves.
• The indoor unit is equipped with an air purger (factory
supplied) at the highest location of the Indoor Unit. If this
location is not the highest of the water installation, air might
be trapped inside the water pipes, which could cause
system malfunction. In that case additional air purgers (field
supplied) should be installed to ensure no air enters the
water circuit.
• For heating floor system, the air should be purged by means
of an external pump and an open circuit to avoid air pockets.
• When the unit is stopped during shut-down periods and the
ambient temperature is very low, the water inside the pipes
and the circulating pump may freeze, thus damaging the
pipes and the water pump. In these cases, the installer shall
ensure that the water temperature inside the pipes does not
fall below the freezing point. In order to prevent this, the unit
has a self-protection mechanism which should be activated
(refer to the Service manual,
• Check that the water pump of the space heating circuit
works within the pump operating range and that the water
flow is over the pump's minimum. If the water flow is below
12 litres/minute for 4.0/5.0/6.0HP unit (6 litres/minute for
2.0/2.5/3.0HP unit), alarm is displayed on the unit.
• An additional special water filter is highly recommended to
be installed on the space heating (field installation), in order
to remove possible particles remaining from brazing which
cannot be removed by the indoor unit water strainer.
• Fresh water must circulate inside the DHW tank water
circuit at least one time per day during the first days after
the installation has been performed. Additionally, flush the
system with fresh water when there is no consumption of
9 PMML0573 rev.1 - 07/2021
"Optional functions" chapter).
DHW during long periods of time.
• Try to avoid long runs of water piping between the tank
and the DHW installation in order to decrease possible
temperature losses.
• lf the domestic cold water entry pressure is higher than the
equipment's design pressure (6 bar), a pressure reducer
must be fitted with a nominal value of 7 bar.
• Ensure that the installation complies with applicable
legislation in terms of piping connection and materials,
hygienic measures, testing and the possible required use of
some specific components like thermostatic mixing valves,
Differential pressure overflow valve, etc.
• The maximum water pressure is 3 bar (nominal opening
pressure of the safety valve). Provide adequate reduction
pressure device in the water circuit to ensure that the
maximum pressure is NOT exceeded.
• Ensure that the drain pipes connected to the safety valve
and to the air purger are properly driven to avoid water being
in contact with unit components.
• Make sure that all field supplied components installed in the
piping circuit can withstand the water pressure and the water
temperature range in which the unit can operate.
• YUTAKI units are conceived for exclusive use in a closed
water circuit.
• The internal air pressure of the expansion vessel tank will be
adapted to the water volume of the final installation (factory
supplied with 0.1 MPa of internal air pressure).
• Do not add any type of glycol to the water circuit.
• Drain taps must be provided at all low points of the
installation to permit complete drainage of the circuit during
servicing.