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The Thermoscreens dry cooling unit operates from its own separate 1 phase electrical
supply (1L+N+E) with a local switched isolator, see Page 12, and the fan within the unit
runs continuously when this electrical supply is connected. If the local switched isolator is
not easily accessible by the end user there should be a 2-pole On/Off switch fitted in an
easily accessible position next to the dry cooling unit. The Mitsubishi Electric interface pcb
fitted inside the dry cooling unit, however, is powered via the S1, S2, S3 wiring from the
outdoor unit and a 2-pole S1, S2 isolator is required for this electrical/communications link.
Room temperature control of the Thermoscreens dry cooling unit is done using a Siemens
RDG400 Manual Room Control that is supplied with the unit. This room control is used to
select the target temperature (set point) of the room air temperature and it then switches
the Mitsubishi Electric cooling system On and Off to achieve this temperature. The room
air temperature is measured using either a return air temperature sensor in the air intake
of the dry cooling unit or via an integral air temperature sensor within the RDG400 manual
room control. This is selectable at the time of commissioning. A volt free remote On/Off
control switch or BMS Dig/Output signal can be connected to the Thermoscreens dry
cooling unit to turn the cooling system On and Off as an alternative to manually switching it
On and Off at the RDG400 manual room control via the target temperature.
A separate thermostat with its air sensor positioned in the air intake is incorporated within
the Thermoscreens dry cooling unit. This is to provide warning of elevated room air
temperatures which could indicate a fault in the air conditioning system or some other
problem. This thermostat can be set during commissioning to between 15°C and 35°C and
terminals are provided within the unit for external monitoring of the contacts opening or
closing on rising temperature. Contacts are rated 16A(4A) at 230v AC.
The Thermoscreens dry cooling unit includes the facility to provide a global error signal
should an error occur in the Mitsubishi Electric heat pump system.
A Mitsubishi Electric PAR-W21MAA Remote Controller is supplied and pre-fitted inside the
left hand end cap of the Thermoscreens dry cooling unit. It is needed for the Mitsubishi
Electric heat pump system to operate and is also useful to diagnose error messages. It is
not used for control of the system by the end user, this is done via the Siemens RDG400
manual room control, see above.
The Thermoscreens dry cooling unit is designed only for use with a Mitsubishi Electric air
to water heat pump system for use on R410A. The complete Thermoscreens/Mitsubishi
Electric air to water heat pump system, including fridge pipework, water pipework system,
wiring, controls, etc. must be installed only by an approved Mitsubishi Electric refrigeration
contractor in accordance with the relevant installation instructions.
Persons using the dry cooling system must be given adequate instruction and supervision
concerning the use of the appliance by a person responsible for their safety. The cooling
system is not intended for use by persons (including children) with reduced physical,
sensory or mental capabilities.
These instructions must be read in conjunction with the separate Mitsubishi Electric
instructions that come with the PUHZ-HW140 Outdoor Unit. All instructions should be kept
by the building facilities manager for future reference.
