SystemAir KA HSI-2-2-S-R-50F-TB2-L2 User Manual

48 systemair
3.7.4 Direct expansion (DX)
Caution
See also section 3.1 General instructions.
In the case of air handling units of the hygienic type, with an internal height H > 1565 mm, where the
direct expanision coil must be slid out from the unit casing regularly for cleaning and disinfection, the DX
coil must be connected to the cooling medium piping outside of the casing, and in such a manner that
allows the disconnection of the cooling coil, its free sliding out from the casing, and, after cleaning, its
replacementinthecasingandleak-freereconnectiontothesystem.
Be sure to install a properly sized siphon on the drain pipe to collect and drain the condensate.
Instructions for the construction, installation and connection are given in section 2.3.5 – Connection of
siphon.
Piping connections
• Coolantandairmustmoveinacounterowconguration.
• Connectthepipingandttingssoastoallowfreeaccesstothecoolingcoilanditssldingoutforinspectionand
maintenance, without hindering access to adjacent sections.
• When tightening piping connections, apply counter-force by means of an appropriate tool (a pipe wrench with pads)
to avoid damaging the DX tubing system.
• Consideringthedirectionofairow,connecttheDXcoilpipingsothattheairinletintotheDXcoilisclosertothe
returnpipe–inthecaseofeitherhorizontalairoworverticalairow,toensuremediumandaircounterow.
• Themostcommonmethodofjoiningissoldering;however,joiningwithquickcouplersispreferableinorderto
reduce the costs of in-service blade cleaning. The thermal insulation of the evaporator extract pipe must provide a
vapour barrier in accordance with applicable standards.
• Ininstallingthethermostatexpansionvalve,followthemanufacturer’sinstructions;installthevalveonthehorizontal
pipe leg, as close as practicable to the DX, upstream of the pressure equalisation and at a proper inclination
consideringthepipethickness.Thesensormustbeinsulatedtoavoidtheinterferenceeffectsofthesurrounding
air. The same applies to the valve sensor and pressure equalisation. We recommend the use of valves with external
pressure equalisation in order to avoid the interference effects of the pressure drop across the evaporator.
• Thedistributorheadmustbemountedinaverticalposition;ifthisisnotpracticable,makesuretoinstallaVenturi
head.
• Sincetheevaporatorisnotttedwithautomaticbladedefrosting,arrangetheelectricinstallationsoastoblock
thecompressoriftheDXfanisnotrunning.Iflargervariationsofintakeairtemperaturesareanticipated(larger
proportions of ambient air), which in turn means DX operation at low power compared to the nominal power, we
recommend the application of cooling power modulation by means of a hot bypass to prevent the blades from
freezing.
• Cleananylingdebrisandotherdirtfromthepipingsystem.
In addition to the thermal expansion valve, the essential equipment for the integration of the DUF in the compressor-
condenser section includes:
• a drying cartridge,
• a solenoid valve (high-pressure – low-pressure limit),
• an inspection glass,
• a collector container, particulary in the cases of long pipes.
Caution
When planning the layout of piping, consider the oil recovery and other phenomena associated with
Freonow.

SystemAir KA HSI-2-2-S-R-50F-TB2-L2 Specifications

General

Brand	SystemAir
Model	KA HSI-2-2-S-R-50F-TB2-L2
Category	Fan
Language	English