Mitsubishi Electric CITY MULTI PUHY-P72-432TNU-A Data Book page 206

1. Installation information
1-3. Precautions for outdoor unit/heat source unit
1-3-1. Installation environment
The outdoor unit with the salt-resistant specification is recommended for use in an area in which it will be exposed to
salt air.
Even when the unit with the salt-resistant specification is used, it is not completely protected against corrosion.
Be sure to follow the directions or precautions described in the Instruction Book and Installation Manual for installation
and maintenance. The salt-resistant specification is referred to in the guidelines published by JRAIA (JRA9002).
Install the unit in an area where the flow of discharge air is not obstructed. If the flow of discharge air is obstructed,
short-cycling of discharge air may occur.
Provide proper drainage around the base of the units; condensation may collect and drip from outdoor units.
Provide water-proofing protection to the floor when installing the unit on the rooftop.
In regions where snowfall can be expected, install the unit so that the outlet faces away from the direction of the wind,
and install a snow guard to protect the unit from snow. Install the unit on a base approximately 50 cm (19-11/16 in.)
higher than the expected snowfall. Close the openings for pipes and wiring, because the ingress of water and small
animals may cause equipment damage. If a SUS snow guard is used, refer to the Installation Manual that comes with
the snow guard and be careful with the installation to avoid the risk of corrosion.
When the unit is expected to operate continuously for a long period of time at outside air temperatures of below 0ºC
(32ºF), take appropriate measures, such as the use of a unit base heater, to prevent ice forming on the unit base.
(Not applicable to the PUMY-Series)
Install the snow guard so that the outlet/inlet faces away from the direction of the wind.
When approximately 50 cm (19-11/16 in.) or more of snow accumulates on the snow guard, remove the snow from the
guard. Install a roof that is strong enough to withstand loads caused by snow in areas where snow accumulates.
Provide proper protection around the outdoor units in places such as schools to avoid the risk of injury.
A cooling tower and heat source water circuit should be a closed circuit so that water is not exposed to the atmosphere.
When a tank is installed to ensure that the circuit has enough water, minimize the contact with outside air to ensure that
the oxygen dissolved in the water is 1 mg/L or less.
Install a strainer (50 mesh or more recommended) on the water pipe inlet on the heat source unit.
Interlock the heat source unit and water circuit pump.
Note the following to prevent the freezing and bursting of pipes when the heat source unit is installed in an area where
the ambient temperature can be 0ºC (32ºF) or below.
Keep the water circulating to prevent it from freezing when the ambient temperature is 0ºC (32ºF) or below.
Before a long period of non-use, be sure to purge the water from the unit.
The salt-resistant unit is resistant to salt corrosion, but not salt-proof.
Please note the following when installing and maintaining outdoor units in a marine environment.
1. Install the salt-resistant unit in an area in which it is not directly exposed to sea breezes, and minimize exposure to salt
water mist.
2. Avoid installing a sun shade over the outdoor unit, so that rain will wash away salt deposits off the unit.
3. Install the unit horizontally to ensure proper water drainage from the base of the unit. Accumulation of water in the base
of the outdoor unit will significantly accelerate corrosion.
4. Periodically wash salt deposits off the unit, especially when the unit is installed in a coastal area.
5. Repair all noticeable scratches after installation and during maintenance.
6. Periodically check the unit, and apply an anti-rust agent and replace corroded parts as necessary.
1-3-2. Circulating water
Regularly check the quality of the water in the heat source unit, following the guidelines published by JRAIA
(JRA-GL02-1994).
A cooling tower and heat source water circuit should be a closed circuit so that water is not exposed to the atmosphere.
When a tank is installed to ensure that the circuit has enough water, minimize the contact with outside air to ensure that
the oxygen dissolved in the water is 1 mg/L or less.
1-3-3. Unit characteristics
When the Thermo ON and OFF is frequently repeated on the indoor unit, the operating status of outdoor/heat source
units may become unstable.
1-3-4. Related equipment
Provide grounding in accordance with the local regulations.
1-3-5. Noise level (Sound pressure level)
The sound pressure level is a value measured in an anechoic room in accordance with the conventional method in JIS
standard. The sound pressure level actually measured at the installation site is usually higher than the value indicated
in this DATA BOOK due to the influence of ambient noise and echoes.
Valve operation noise and refrigerant flow noise may occur from inside the outdoor unit/heat-source unit.
MEES20K084
Installation information
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