Mitsubishi Electric PURY-WP-YJM-A Data Book page 218

6. Installation information
6-3. Precautions for Fresh air intake type indoor unit
6-3-1. Usage
ŒThis unit mainly handles the outside air load, and is not designed to maintain the room temperature. Install other air con-
ditioners for handling the air conditioning load in the room.
6-3-2. Unit characteristics
ŒThis unit cannot perform the drying operation. The unit will continue the fan operation and blow fresh air (air that is not
air-conditioned) when the Heating Thermo-OFF or Cooling Thermo-OFF mode is selected.
ŒThe fan may stop tentatively when the unit is connected to the simultaneous cooling/heating operation type outdoor unit
(R2, WR2 series) or during the defrost cycle.
ŒThis unit switches the Thermo ON or OFF depending on the room temperature. The outside air is directly supplied into
the room during Thermo OFF. Take caution of the cold supply air due to low outside air temperature and of condensation
in the room due to high humidity of the outside air.
ŒOutside air temperature ranges for the operation must be as follows:
Cooling: 21ºCD.B./15.5ºCW.B. ~ 43ºCD.B./35ºCW.B.
Heating: -10ºCD.B.~ 20ºCD.B
The unit is forced to operate Thermo OFF (fan operation) when the outside air temperature is as follows.
Cooling: 21ºCD.B or below; Heating: 20ºCD.B or above
ŒEither a remote controller (sold separately) or a remote sensor (sold separately) must be installed to monitor the room
temperature.
ŒIf only this unit is used as an indoor unit, condensation may form at the supply air grill while the unit is operated in the
cooling mode. This unit cannot operate dehumidifying.
ŒUse the unit in the way that the airflow rate will not exceed the 110% of the rated airflow.
6-4. Precautions for Outdoor unit/Heat source unit
6-4-1. Installation environment
ŒOutdoor unit with salt-resistant specification is recommended to use in a place where it is subject to salt air.
ŒEven when the unit with salt-resistant specification is used, it is not completely protected against corrosion. Be sure to
follow the directions or precautions described in Instructions Book and Installation Manual for installation and mainte-
nance. The salt-resistant specification is referred to the guidelines published by JRAIA (JRA9002).
ŒInstall the unit in a place where the flow of discharge air is not obstructed. If not, the short-cycling of discharge air may
occur.
ŒProvide proper drainage around the unit base, because the condensation may collect and drip from the outdoor units.
Provide water-proof protection to the floor when installing the units on the rooftop.
ŒIn a region where snowfall is 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 expect-
ed snowfall. Close the openings for pipes and wiring, because the ingress of water and small animals may cause equip-
ment damage. If SUS snow guard is used, refer to the Installation Manual that comes with the snow guard and take
caution for the installation to avoid the risk of corrosion.
ŒWhen 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 icing on the unit base. (Not applicable to
the PUMY series)
ŒInstall the snow guard so that the outlet/inlet faces away from the direction of the wind.
ŒWhen the snow accumulates approximately 50 cm or more on the snow guard, remove the snow from the guard. Install
a roof that is strong enough to withstand snow loads in a place where snow accumulates.
ŒProvide proper protection around the outdoor units in places such as schools to avoid the risk of injury.
ŒA cooling tower and heat source water circuit should be a closed circuit 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 so that the
oxygen from being dissolved in the water should be 1 mg/L or less.
ŒInstall a strainer (50 mesh or more recommended) on the water pipe inlet on the heat source unit.
ŒInterlock the heat source unit and water circuit pump.
ŒNote the followings to prevent the freeze bursting of pipe when the heat source unit is installed in a place where the
ambient temperature can be 0ºC or below.
ŒKeep the water circulating to prevent it from freezing when the ambient temperature is 0ºC or below.
ŒBefore a long period of non use, be sure to purge the water out of the unit.
6-4-2. Circulating water
ŒFollow the guidelines published by JRAIA (JRA-GL02-1994) to check the water quality of the water in the heat source
unit regularly.
ŒA cooling tower and heat source water circuit should be a closed circuit 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 so that the
oxygen from being dissolved in the water should be 1 mg/L or less.
SYSTEM DESIGN 4 - 47