systemair 55
Connection
• The indirect gas heating coil section must always be located in the positive pressure part of the air handling unit –
downstreamfromthesupplyfan,topreventthemixingofsupplyairanduegasesintheeventofaheatexchanger
defect.
• The heat exchanger is installed into its casing on guide rails that facilitate its sliding out from the section in the event
of defect or damage. For this purpose, provide a clearance space on the unit service side of a width equal to or
greater than the external width of the air handling unit.
• Upstreamanddownstreamofthegasheatersection,theinstallationofemptysectionsisspeciedplanned,witha
modularlengthofmin.600mm,withaccessintotheinteriortoenablecheckingtheconditionofthegasheater.
• Discharge from the pan must be led through the section bottom into a siphon and acid neutralisation unit into the
sewage system.
• Thecondensatedrainconnection,locatedintheinspectionopeningatthebottombackpartofthetuberegister
collector,mustbeledthroughthebackwallofthesectioncasing.
• The safety pressure switch, the safety thermostat, the temperature limiter and the operating thermostat must be
installed outside the section casing. In the case of an outdoor unit, protect these elements, as well as the burner, by
installing them in a waterproof and thermally insulated protection chamber.
• Thegasburnermustbexedtothecombustionchamberrimfromtheoutersideofthesectioncasing.Forthis
purpose,applyangesadaptedtothesizeandtypeofgasburner.
• Inthecaseofindoorairhandlingunits,makethenecessaryprovisionsforadequateinowofcombustionair,natural
ventilationoftheroomandextractionofuegases.
• In the case of outdoor units that are exposed to weather elements (wind, rain, snow, etc.), the gas burner must be
installedinawaterproofandthermallyinsulatedprotectionchamber,which,onitsbottomside,mustbettedwith
an opening to freely supply combustion air. The protection chamber must be large enough to also accommodate the
safety pressure switch, the safety thermostat, the temperature limiter and the operating thermostat. The chamber
must have enough capacity (to the left and to the right of the gas burner) to allow the installation of the gas supply
train.
• Indesigningthemethodfortheextractionofuegases,consultacompetentchimney-sweepingservice.Where
thesupplyofasectionwithastackisordered,thestackmustbesizedandconstructedinaccordancewiththe
applicable regulations, laws and standards. To facilitate obtaining consent from a chimney-sweep service, design
documentsshouldbedrawnupforthestack,includingthesolutionsfortheextractionandneutralisationoftheue
gas condensate.
• Connectthegasheatertothestackinaccordancewiththerequirementsapplicabletostacksforgas-red
installations.Thejointbetweenthestackconnectionandthestacktubemustbewaterprooftopreventuncontrolled
dischargeofcondensateintheeventofuegascondensation.
• Thegasheaterstackconnectiondoesnotneedtomaintainanaturaldraft.
• Electric cables must not be run inside the section casing. In the case of an outdoor unit, a gas burner protection
chamber may be utilised to accommodate cables, provided that the cables do not obstruct the servicing of the
equipment;alternatively,cablesmayrunonthefreeoutersurfacesofthecasing(backwall,bottom,etc.),in
agreement with the designer or the customer.
• The gas supply line must be arranged so as not to obstruct the servicing of the unit’s functional sections and to allow
any functional element to be slid out of the casing of the air handling unit as necessary.
• In the gas heating coil section design, the free circulation of air must be ensured between the unit interior and the
environment, for cooling purposes. Fit the opening in the ceiling or on the side with a spring-driven damper and
installaductleadingfromthedampertotheopenair.Thedamperandtheductmustbethermallyinsulated;the
insulation material must be non-combustible. In the event of power supply failure or any other fault that may result
in the abrupt failure of unit interior cooling or its overheating, the damper must open and allow natural cooling of the
gas heating coil.
• The sealing between the casing frame and the panels of the left and right adjacent sections and the sealing of the
jointsbetweentheleftandrightsectionsandthegasheatingcoilmustbeprovidedbymeansofaceramicbre
sealing tape 19 x 5 mm, resistant to temperatures in a range from –20 to +1200°C. In the case of putty sealing, apply
a high resistance grade glue-sealing paste, stable at temperatures in a range from –40 to +250 °C, and, on a short-
term basis, to +300°C.
• All the electric cables, cable glands and protection tubes installed inside the casings of the left and right sections
adjacent to the gas heating coil section must have insulation resistant to high temperatures.
• Forthepurposesoflteringairimmediatelyupstreamofthegasheatingcoil,applyametallterwithnoEPDM
sealingtapeandwithnobottompan(unlessgreasesaretobelteredout).
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