Mitsubishi Electric Y Series Manual page 238

Installation Information
238
2. Precautions for Indoor unit, HBC controller, and
BC controller
2-1. Operating environment
♦The refrigerant (R410A) used in the air conditioner is non-toxic and nonflammable. However, if the refrigerant
leaks, the oxygen level may drop to harmful levels. If the air conditioner is installed in a small room, measures
must be taken to prevent the refrigerant concentration from exceeding the safety limit even if the refrigerant
leaks.
♦If the units operate in cooling mode at a humidity above 80%, condensation may collect and drip from the
indoor units.
♦Regular checking and cleaning of the drain drainage paths, such as the drain pan or the drain pump, is
recommended to prevent clogging. The neglect of a clogged drain pump may trigger the water-leakage
protection function which stops operation of the entire system.
2-2. Unit characteristics
♦The return air temperature display on the remote controller may differ from the displays on the other
thermometers.
♦The clock on the remote controller may be displayed with a time lag of approximately one minute every month.
♦The temperature measured by the built-in temperature sensor on the remote controller may differ from the
actual room temperature due to the effect of the wall temperature.
♦Use the built-in thermostat on the remote controller or a separately-sold thermostat when indoor units installed
on or in the ceiling operate the automatic cooling/heating switchover.
♦The room temperature may rise drastically due to Thermo OFF in areas where the air-conditioning load is
large, such as computer rooms.
♦Be sure to use a regular filter. If an irregular filter is installed, the unit may not operate properly, and operating
noise may increase.
♦The room temperature may increase above the preset temperature in environments in which the heating or air-
conditioning load is small.
2-3. Unit installation
♦The insulation for the gas pipe between the HBC controller and the outdoor/heat source unit must be at least
20 mm thick. If the unit is installed on the top floor or in a high-temperature, high-humidity environment, thicker
insulation may be necessary.
♦The insulation for the low-pressure pipe between the BC controller and the outdoor/heat source unit must be at
least 20 mm thick. If the unit is installed on the top floor or in a high-temperature, high-humidity environment,
thicker insulation may be necessary.
♦Do not have any branching points on the downstream of the refrigerant pipe header.
♦When a field-supplied external thermistor is installed or when a device for demand control is used, the unit
may stop abnormally or damage may occur to the electromagnetic contactor. Consult your local distributor for
details.
♦When indoor units employ fresh air intake, install a filter in the duct (locally procured) to remove dust from the
air.
♦The 4-way or 2-way Airflow Ceiling Cassette Type units that have an outside air inlet can be connected to the
duct, but need a booster fan to be installed at site. Refer to the chapter "Indoor Unit" in the DATA BOOK for the
available range for fresh air intake volume.
♦Employing fresh air intake for the indoor unit may increase the sound pressure level.