Cooling Circuit - Lennox @DNOVA THND 045 Installation, Operating And Maintenance Manual

1.3

Cooling circuit

The entire cooling circuit is built in the Lennox factory using only components of the finest quality brands
and processes conforming to the specifications of Directive 97/23 for brazing and testing.
 Compressors: only scroll-type compressors of leading international manufacturers are used in the
THND/U/X units. Today scroll compressors represent the best solution in terms of reliability, efficiency
and MTBF.
 Cooling components:
Molecular mesh activated-alumina filter dryer
o
Flow indicator with humidity indicator. Indications are provided directly on the sight glass.
o
Thermostatic valve with external equalization and integrated MOP function.
o
High and low pressure switches
o
Schrader valves for checks and/or maintenance
o
 Electric control board: The electric control board is constructed and wired in accordance with Directives
73/23/EEC and 89/336/EEC and related standards. The board may be accessed through a door after
the main switch has been put off. All the remote controls use 24 V signals powered by an insulating
transformer situated on the electric control board. NOTE: the mechanical safety devices such as the
high pressure switch are of the kind that trigger directly; their efficiency will not be affected by any faults
occurring in the microprocessor control circuit, in compliance with 97/23 PED.
 Control microprocessor: the microprocessor built into the unit allows the different operating parameters
to be controlled from a set of pushbuttons situated on the electric control board;
Switching on/off of compressor to maintain the temperature set point T inside the shelter
o
Alarm management
o
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Alarm signalling
o
Display of operating parameters
o
RS232, RS485 serial output management (optional)
o
Phase sequence error [Not displayed by the mP, but prevents the compressor from starting up]
o
[see microprocessor control manual for further details, also in relation to particular customer
specifications]
@DNOVA THN_R410A-IOM-1506-E
High / low pressure
Dirty filters alarm
Air flow alarm
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