Mitsubishi Electric Y Series Manual page 241

♦Outside air is directly supplied into the room during Thermo OFF. Be careful with regard to cold supply air due
to low outside air temperatures and of condensation in the room due to high humidity of the outside air.
♦If the airflow rate is higher than the usable range, condensation may drip from the air outlet, and the air flow
rate will be automatically reduced by the fan motor control. If the air flow rate is lower than the usable range,
condensation may form on the surface of the unit.
♦Combining fresh air intake-type indoor units with other types of indoor units to respond to the internal thermal
load may cause conflict in operating modes. It is not recommended when a fresh air intake-type indoor unit is
connected to a Y or WY-Series unit.
♦Depending on the air-conditioning load, outside temperature, and the activation of protection functions, the
desired preset temperature may not always be achieved and the discharge temperature may swing. Note that
untreated outside air may be delivered directly into the room upon the activation of protection functions.
♦Fresh air intake-type indoor units cannot be connected to PUMY and cannot be connected to an outdoor unit
together with PWFY-Series units.
4. Precautions for outdoor unit/heat source unit
4-1. 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
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, 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 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 or below.
♦Keep the water circulating to prevent it from freezing when the ambient temperature is 0ºC or below.
♦Before a long period of non-use, be sure to purge the water from the unit.
Installation Information
241