Mitsubishi Electric CMB-WM108V-AA Service Handbook page 28

[ I Read Before Servicing ]
12. Installation restrictions for outdoor units
• R32 is heavier than air—as well as other refrigerants—so tends to accumulate at the base (in the vicinity of the
floor). If R32 accumulates around the base, it may reach a flammable concentration in case the room is small.
To avoid ignition, maintain a safe work environment by ensuring appropriate ventilation. If the refrigerant leaks
in a room or an area that has insufficient ventilation, refrain from using flames until the work environment is
improved by ensuring appropriate ventilation.
• Do not install the outdoor unit in a semibasement, basement, or machinery room, where the refrigerant
stagnates in the case of leak of refrigerant.
• Install the outdoor unit in a space where at least one side is open.
Good
Figure 1
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(Example: semibasement, basement)
13. Installation restrictions for HBC controllers
Observe the following restrictions that apply to the installation of HBC controller.
[Restrictions for HBC controller installation]
• There must be at least 1.8 meters from the floor to an HBC controller (indicated as H in Figure 3).
• Do not place an ignition source in a space where an HBC controller is installed or adjacent spaces not shielded
by firewalls (refer to Table 2).
Examples: Lighters, combustion heaters, combustion boilers, and combustion cookers
• Figure 2 shows the minimum floor areas required for given amounts of refrigerant in various refrigerant
systems. Make sure the installation conditions meet the requirements shown in the figure (system refrigerant
amount / minimum floor area ≤ 0.11).
• When installing an HBC controller in a ceiling space, make sure the relationship between the total floor areas of
the rooms that share the ceiling space and the total refrigerant amount in the system falls within the range.
• The ceiling material should not be made of highly breathable materials (e.g., mesh ceiling).
When the ceiling is made of mesh (highly breathable material), the unit should be visible through the ceiling
from below.
When the ceiling is made of mesh (highly breathable material), calculate the refrigerant concentration based
only on the area of the room directly below the unit, and make sure the value obtained satisfies the restrictions.
(In Figure 3, for example, if the ceiling is made of mesh, calculate the refrigerant concentration based only on
the floor area of Room B.)
• If the ceiling space is divided into separate areas by firewalls, calculate the refrigerant concentration based on
the floor area of the room under the relevant enclosed ceiling area, and make sure the calculation results
satisfy the installation restrictions (refer to Table 1).
Example: Installation of an HBC controller in the ceiling space above Room B (The ceiling is not made of highly
breathable material.)
Floor area = Floor area of Room A + Floor area of Room B
• When installing an HBC controller in a machine room or a riser, minimum floor area requirements shown in
Figure 2 (system refrigerant amount / minimum floor area ≤ 0.11) must be observed, and the HBC controller
must be installed at a height of 1.8 meters or higher.
• All of the above-mentioned restrictions apply not only to new installations but also to relocations and layout
changes.
HWE1708A
(Example: space with a louver)
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