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The Thermoscreens Air Curtain requires a permanent mains electrical supply from a local
switched isolator. Electrical power to the PAC-AH…AHU controller is then fed from the air
curtain. Electrical power to the Mitsubishi Electric compressor unit(s) and BC Controller is
fed separately in the normal way (see separate Mitsubishi Electric instructions). If the
defrost cycle electric heaters inside the air curtain are to be used during the heating mode
defrost cycle the electrical supply to the air curtain needs to be 3-phase (3L+N+E). If the
defrost cycle electric heaters are not required they can be permanently disconnected at
installation and a single phase electrical supply (1L+N+E) fed to the air curtain instead,
see 'Installation - Electrical Supply'.
Warning:
Air curtain fans continue to operate during heating mode system defrost to
maintain an air stream across the doorway. With the defrost cycle electric heaters
operating the discharge air temperature from the air curtain is kept to a few degrees below
that of the indoor ambient air temperature during the duration of system defrost. If the
electric heaters are disconnected, discharge air temperatures could be very cold,
approximately 6ºC during the defrost and defrost times will also be extended, particularly
with the R2-Series System. Defrost does not occur with WY and WR2 systems so the
defrost cycle electric heaters should be disconnected on these systems.
There are various control cables that are wired on site to the PAC-AH…AHU Controller
and the Thermoscreens Air Curtain that provide control for the operation of the unit. These
are:-
•
Start/Stop of air curtain fans
•
Operation of LEV(s) for control of heating or cooling output
•
Thermistor
sensors
•
PAR-21MAA Remote Controller for end user manual control, if used
•
On/Off of electric heaters inside the air curtain during system defrost (if used)
•
Condensate alarm derived from condensate pump alarm sensor (if used)
•
M-Net communications link to the Mitsubishi Electric Compressor Unit.
(see also wiring diagrams)
The Thermoscreens Air Curtain is supplied with an integral condensate drain tray to
enable the air curtain to be used in cooling mode during warm weather, if so desired. If it is
intended to use the air curtain in cooling mode a suitable condensate pump (not supplied
by Thermoscreens) must be supplied by the installer. The condensate pump must be of
sufficient capacity, self priming and capable of providing the appropriate suction head so
the pump will lift condensate out from the top of the air curtain but can be hidden in a
remote location if necessary. Suitable condensate pumps are Peristaltic or Rotary
Diaphragm type. We recommend the Blue Diamond rotary diaphragm type with cooling
signal sensor (drainStik) manufactured by Charles Austen Pumps Ltd.
(www.miniblue.co.uk).
It is recommended that the condensate pump has the facility so it only operates when the
air curtain is in cooling mode by detection of water in the drain tray or by detecting a
cooling differential in the airflow. It should also have a pump overrun to empty the drain
tray as much as possible when the air curtain is switched off. It should have an alarm
system with appropriate sensor that will give a volt-free signal (open circuit = alarm). This
will stop the air curtain cooling if the condensate drain tray is in danger of flooding, air
curtain fans will continue to operate. Other City Multi indoor units are unaffected if the air
curtain condensate alarm occurs. There is a plastic fixing bracket with 8mm diameter hole
