Hitachi YUTAKI M R32 Series - Requirements and Recommendations for the Hydraulic Circuit

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PMML0600 rev.0 - 06/2022
5
SPACE HEATING AND DHW FOR YUTAKI M / YUTAKI HYDROSPLIT
DRAIN AND WATER PIPING
5.5.4 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 “4.3.2 Pump performance curves”.
• The units are equipped with a manual air purger (factory supplied) at the highest location of
the 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
(eld supplied) should be installed to ensure no air enters the water circuit.
• For heating oor system, the air should be purged by means of an external pump and an open
circuit to avoid air bags.
• When the unit is stopped during shut-o 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, “Optional
functions” chapter).
• Check that the water pump of the space heating circuit works within the pump operating
range and that the water ow is over the pump’s minimum. If the water ow is under 12 litres/
minute for 4.0-7.0HP units (6 litres/minute for 2.0-3.0HP units) (with ow switch tolerance),
alarm will be displayed on the unit.
• An additional special water lter is highly recommended to be installed on the space heating
(eld installation), in order to remove possible particles remaining from brazing which cannot
be removed by the unit water strainer.
• In case of YUTAKI Hydrosplit in combination with YUTAKI H, it is mandatory to install
additional water strainer into YUTAKI Hydrosplit outdoor unit water inlet connection.
• When selecting a tank for DHW operation, take into consideration the following points:
✓ The storage capacity of the tank has to meet with the daily consumption in order to avoid
stagnation of water.
✓ Fresh water must circulate inside the DHW tank water circuit at least one time per day
during the rst days aer the installation has been performed. Additionally, ush the
system with fresh water when there is no consumption of 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
(10 bar), a pressure reducer must be tted 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 specic
components like thermostatic mixing valves, Dierential pressure overow 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 or oriented to avoid water being in contact with unit components.
• Make sure that all eld supplied components installed in the piping circuit can withstand the