• Hitachi cannot anticipate every possible circumstance
that might involve a potential hazard.
• This air to water heat pump has been designed for
standard water heating for human beings only. Do not
use this for other purposes such as for drying clothes,
heating foods or for any other heating process (except
swimming pool).
• No part of this manual may be reproduced without
written permission.
• If you have any questions, contact your service
contractor of Hitachi.
• Check and make sure that the explanations of each
part of this manual correspond to your air to water
heat pump model.
• Refer to the models codification to confirm the main
characteristics of your system.
• Signal words (NOTE, DANGER and CAUTION) are used
to identify levels of hazard seriousness. Definitions for
identifying hazard levels are provided in initial pages of
this document.
• The operation modes of these units are controlled by
the unit controller.
• This manual should be considered as a permanent
part of the air to water heat pump. It gives a common
description of and information for this air to water
heat pump which you operate as well as for other
models.
• Keep the water temperature of the system above the
freezing temperature.
• Water temperature (min/max): 5 °C / 65 °C
• Water pressure (min/max): 0.1 MPa / 0.3 MPa
• This equipment must be connected to the water main.
• lf the domestic cold water entry pressure is higher
than the equipment's design pressure (1 MPa),
pressure reducer must be fitted with a nominal value
of 0.7 MPa.
3. GENERAL DIMENSIONS
3.1 Minimum floor area for R32 units
Please refer to outdoor unit installation manual for
charge calculation.
1. Check the refrigerant charge:
a. If the refrigerant charge is <1.84 kg, no minimum
area is required.
b. If the refrigerant charge is >1.84 kg, check the
Table 1 for minimum floor area (A
2. Calculate the room area:
a. Check the Table 1 to see the corresponding
minimum room area (room A) according to
the maximum refrigerant charge (m
installation height (H
b. In case that the room area is not complying the
minimum area requirement, check for an adjacent
room (room B).
EN
PMML0668 rev.0 - 09/2024 - 1000017438
).
min
) and the
c
).
0
3. Determine total floor area of room A and room B:
a. Calculate the area of room B adjacent to the
room A.
b. Determine if the A
min total
B) based on the total refrigerant charge (m
Table 1.
c. The total floor area both room A and room B must
exceed A
.
min total
4. Determine Minimum Venting Opening Area (VA
Natural Ventilation
9 For connected rooms and natural ventilation, the
following conditions must be satisfied:
9 High-Level Openings: Openings located more than
300 mm above the floor will not count towards
the required minimum ventilation area (A
9 Low-Level Openings: At least half of the required
ventilation area (A
nv,min
200 mm from the floor.
9 Lowest Point of Openings: The base of the lowest
openings must be no higher than the release
point of the refrigerant and should not exceed
100 mm from the floor.
9 Permanent Openings: Ventilation openings must
be permanent and cannot be sealed.
9 Connecting Room Openings: Openings that
connect rooms must have a height of at least
20 mm between the wall and the floor.
9 Additional Higher Opening: A second, higher
opening is required. This additional opening
should be at least 50% of the A
no less than 1.5 meters above the floor.
Room A
VA
min
>0.5 VA
Room A + Room B
(A
= Room A + Room
min total
) from
c
) for
min
).
nv,min
) must be situated below
and positioned
nv,min
H
0
H
0
H
0
min
2