Selecting An Installation Site; About The Product; Installation Site; Securing Installation And Service Space - Mitsubishi Electric City Multi CMH-WM250V-A Installation Manual

Air-conditioners for building application indoor/outdoor unit
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2. Selecting an installation site

2.1. About the product

This unit uses R32-type refrigerant.
Only the "W" models of indoor units can be connected.
Piping for systems using R32 may be different from that for systems using
conventional refrigerant because the design pressure in systems using R32 is
higher. Refer to the Data Book for more information.
Some of the tools and equipment used for installation with systems that use other
types of refrigerant cannot be used with the systems using R32. Refer to the Data
Book for more information.
Do not use the existing piping, as it contains chlorine, which is found in
conventional refrigerating machine oil and refrigerant. This chlorine will
deteriorate the refrigerant machine oil in the new equipment. The existing piping
must not be used as the design pressure in systems using R32 is higher than that
in the systems using other types of refrigerant and the existing pipes may burst.

2.2. Installation site

Observe the following precautions when installing the hydro unit outside.
Install the unit with adequate space around it for servicing.
Do not install the unit in a place that would result in the piping length restrictions
being exceeded.
Check for refrigerant leaks before service.
- If the refrigerant leaks, fire may result.
Install or store the unit in a place not exposed to direct radiant heat from other
heat sources or naked flame or other ignition sources.
Do not install the unit in any oily steamy place or near any machine that
generates high frequencies. Doing so may cause a risk of fire, erroneous
operation or condensation.
Do not install the unit where it could be salt-damaged.
Depending on the operation conditions, hydro unit generates noise caused by
water pump even when operating normally. Therefore install the unit in places
such as machinery room that follows EUROPEAN STANDARD.
Install indoor unit and hydro unit at least 5 m away from each other when installed
in a space with low background noise, e.g., hotel rooms.
Allow enough space and access to ensure water piping, refrigerant piping and
electrical wiring can be easily connected.
Avoid places exposed to the generation, inflow, accumulation or leakage of
flammable and sulfuric gases.
Ensure a downward gradient of at least 1/100 for drain piping.
Properly install the unit on a stable, load-bearing surface.
1. Hydro unit Top view [Fig. 2.2.1] (P.2)
<A> Refrigerant piping side
<B> Water piping side
Provide 2 inspection holes 450 mm square in the ceiling surface as shown in
[Fig. 2.3.1] (P.2).
Install the unit in a suitable location (such as machinery room that follows
EUROPEAN STANDARD) away from places regularly occupied. Avoid installing
in the occupied space.
If necessary, install the unit on a raised base of the following specifications (not
supplied) to prevent damage from snow.
Material: Angle iron (Build a structure that snow and wind can pass through.)
Height: Expected maximum snowfall plus 200 mm (7-7/8 in)
Width: Within the unit width (If the raised base is too wide, snow will accumu-
late on the raised base.)
When the unit is used in a cold region and the heating operation is continuously
performed for a long time when the outside air temperature is below freezing,
install a heater on the raised base or take other appropriate measures to prevent
water from freezing on the raised base.
When installing a panel heater, provide sufficient space for maintenance
accordingly. For details, refer to the Data Book or installation manual for the
panel heater.
Warning:
Be sure to install the unit in a place that can sustain the entire weight.
If there is a lack of strength, it may cause the unit to fall down, resulting in an
injury.
Caution:
Be sure to install the unit horizontally.
Install the hydro unit level (less than 1° tilt), so that the drain pan can
function correctly.
Install the hydro unit in an environment where the temperature in always
above 0°C if water circuit does not contain antifreeze liquid.
10

2.3. Securing installation and service space

Allow for the following service space after installation
(Servicing can be performed from the front and back of the unit.)
[Fig. 2.3.1] (P.2)
<A> Front view
A Service space

2.4. Checking the installation site

Check that the difference of elevation between indoor and outdoor units and the
length of refrigerant piping are within the following limitations.
1. CMH-WM*V-A
[Fig. 2.4.1] (P.2)
A Outdoor unit
C Indoor unit
E Cap
G Header branching
I Water piping
Item
Total piping length
Farthest indoor unit from outdoor unit
(L1)
Between outdoor unit and hydro unit
(refrigerant pipework)
Farthest indoor unit from hydro unit
(L3)
Height between outdoor unit and indoor
unit (outdoor unit above indoor unit)
Height between outdoor unit and indoor
unit (outdoor unit below indoor unit)
Height between outdoor unit and hydro
unit (outdoor unit above hydro unit)
Height between outdoor unit and hydro
unit (outdoor unit below hydro unit)
Height between hydro unit and indoor
unit (hydro unit above indoor unit)
Height between hydro unit and indoor
unit (hydro unit below indoor unit)
Height between indoor units
*1 The maximum length is 90 m, depending on the unit model and installation conditions.
For more detailed information, contact your local distributor.
*2 The maximum length is 60 m, depending on the unit model and installation conditions.
For more detailed information, contact your local distributor.
Warning:
(When R32 refrigerant is used)
Do not use means to accelerate the defrosting process or to clean, other 
than those recommended by the manufacturer.
The unit shall be stored in a room without continuously operating ignition
sources (for example: open flames, an operating gas appliance or
an operating electric heater.)
Do not pierce or burn.
Be aware that refrigerants may not contain an odour.
When installing a hydro unit in an unoccupied space or outdoors, take
safety measures in accordance with the European Standard, based on the
system refrigerant amount and the room volume as shown in the figure
below. (The installation restrictions can be simply found by using the
flowchart provided on a separate sheet.)
80
NG (ISO 5149)
70
60
At least two safety
50
measures are
40
required.
30
20
10
0
0
50
100 150 200 250 300 350 400 450 500 550 600 650
Room volume [m
Notes:
Refer to the outdoor unit manual about additional refrigerant amount of
hydro unit and maximum amount of system refrigerant.
Be sure to protect pipings from physical damage.
<B> Top view
B 1st branching
D Hydro unit
F Joint
H Refrigerant piping
Piping in the
Max.
Max. equivalent
figure
length
length
A+A'+B+C+D+E
1000
-
+a+b+c+d+e+f+g
A+A'+C+D+E+g/
165
190
A+B+c
A
110
-
A'+C+D+E+g/
60
60
A'+B+c
H
90
-
H'
60
-
H1
50 *1
-
H1'
40 *2
-
H2
50
-
H2'
40
-
h1
30
-
At least one safety
measure is required.
Construction guidance
]
3
(Unit: m)

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