Specifications

12
A. Vent System Design
Therearethreebasicwaystoventthisboiler:
• Horizontal (“Side Wall”) Concentric Venting-Ventsystemexitsthebuildingthroughanoutsidewall.Concentric
ventingconsistsofa“pipewithinapipe”.Fluegasexitsthebuildingthroughtheinnerpipeandcombustionairis
drawnintotheboilerthroughthespacebetweentheinnerandouterpipe.
• Horizontal (“Side Wall”) Twin Pipe Venting-Ventsystemexitsthebuildingthroughanoutsidewall.Combustion
airanduegasareroutedbetweentheboilerandoutdoorsusingseparatepipes.
• Vertical Concentric Venting-Ventsystemexitsthebuildingthroughtheroof.Concentricventingconsistsofa"pipe
withinapipe".Fluegasexitsthebuildingthroughtheinnerpipeandcombustionairisdrawnintotheboilerthrough
thespacebetweentheinnerandouterpipe.
• Vertical Twin Pipe Venting-Ventsystemexitsthebuildingthrougharoof.Combustionairanduegasarerouted
betweentheboilerandoutdoorsusingseparatepipes.
 Allofthesesystemsareconsidered“directvent”becauseinallofthem,airforcombustionisdrawndirectlyfromthe
outdoorsintotheboiler.AdescriptionofalloftheseventingoptionsareshowninTables7.1and7.9.Forclarity,these
ventoptionsarenumberedfrom1to6.OneoftheventoptioncolumnsinTables7.1or7.9mustmatchtheplanned
ventandairintakesystemexactly.Inaddition,observethefollowingguidelines:
1) Approvedventsystems-UseonlyoneoftheapprovedventsystemsshowninTables7.4a,7.4bor7.5.Thesevent
systemsfallintotwobasiccategories:
• Concentric Vent System-Thestandardboilerissuppliedwithaconcentricventsystemhavingamaximumusable
lengthof25”(Figure2.1).Forlongerruns,additionalstraightlengthsandelbowsareavailablefromU.S.Boiler.In
somecases,largerdiameterconcentricpipemustbeused.EachU.S.Boilerconcentricventcomponentconsistsofan
innerpipeofpolypropyleneandtheouterpipeofsteel.Integralgasketsoneachconcentricttingprovideagastight
seal.AlistofallU.S.BoilerconcentricventcomponentsisshowninTables7.4aor7.4b.
Inthismanual,concentricpipesizesarecalledoutintermsoftheinnerandouterpipenominaldiametersin
millimeters.Forexample,“60/100mm”pipeconsistsofa60mmexhaustpipeinsidea100mmdiameterouterpipe.
• Twin Pipe Vent Systems-Approvedventsystemsaremadeofaspecialstainlesssteelalloy(AL29-4C)forprotection
againstcorrosiveuegascondensate.Theyaredesignedtoprovideagastightsealatalljointsandseamssothatue
gasdoesnotenterthebuilding.Eachapprovedventsystemhasauniquemethodforinstallation-do not attempt to
mix components from different vent systems.AlistofapprovedtwinpipeventsystemsisshowninTable7.5.Note
thataspecialventcollar(U.S.BoilerP/N101004-01)isrequirediftheboileristobeventedwithoneoftheapproved
stainlessventsystems.
VII Venting
WARNING
FAILURE TO VENT THIS BOILER IN ACCORDANCE WITH THESE INSTRUCTIONS COULD
CAUSE FLUE GAS TO ENTER THE BUILDING RESULTING IN SEVERE PROPERTY DAMAGE,
PERSONAL INJURY, OR DEATH:
* Do not attempt to vent this boiler with galvanized, PVC, or any other vent system not listed in
Tables 7.4a or 7.4b.
* Do not attempt to mix components from different approved vent systems.
* Do not obtain combustion air from within the building.
* Do not install a barometric damper or drafthood on this boiler.
CAUTION
Moisture and ice may form on the surfaces around the vent termination. To prevent
deterioration, surfaces should be in good repair (sealed, painted, etc.)