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26 | InstallationThe free area of the openings must be taken into account restrictionsfrom the louvers and screens. The louver manufacturer should beconsulted for the percentage of free area available. When free area is notknown, metal louvers typically have 60-70% of free area, woodenlouvers have between 20-25% of free area. Louvers should be in a fixedposition or interlocked with equipment so that they open automaticallyduring equipment operation.The combustion air damper opening shallbe located as follows: top louver shall began within 12” of the ceiling andthe bottom louver within 12” of the floor as prescribed in NFPA 54.Direct intake method - If outside combustion air is required, air may bedrawn from the outdoors via a duct connected directly to the burnerintake. The duct shall be constructed of galvanized steel or a materialhaving equivalent strength and rigidity. Refer to the burnermanufacturer's recommendations and installation instructions foradditional guidelines and application requirements.≥3°≥3°15.9 Combustion Air from an adjacent roomWhere combustion air is to be used from within the building, air must beprovided into the equipment room through two permanent openingsinto the inferior building. Each opening must have a minimum free areaof 1 square inch for each 1,000 Btuh of the total input rating of all fuelburning equipment in the space. The louvers shall be located as follows:top louver shall start within 12” of the ceiling and the bottom louverwithin 12” of the floor as prescribed in NFPA 54.5.10 Condensate RemovalThe exhaust vent pipe must be pitched at least ¼ “ per foot of length backto the boiler. This will allow condensate to drain back to the unit to bedisposed. Low spots in the venting where condensate may collectshould be avoided. A plastic hose or PVC drain pipe may be used tocondensate discharge to the neutralization system. Care should betaken to avoid kinks and from raising the drain line above the trapassembly.5.11 Condensate5.11.1 Draining the condensateCondensing boilers produce a flow of condensate that varies accordingto operating conditions. The maximum hourly production of condensateis shown in the technical specifications table for each individual model.The condensate drain system must be suitably dimensioned to cope withthe flow produced. Also, pipe and hose diameter must not be less than1” at any point. This diameter corresponds to that of the boiler’scondensate drain fitting [1].The connection to the waste water drain pit must be made in compliancewith national and local legislation and standards.To prevent combustion fumes from leaking into the air of the boilerroom, the condensate drain pipe must incorporate a siphon creating aminimum head equivalent to the fireside pressure drop ( Tab. 5,page 9) plus 1 inch W.C. The connecting pipes between the boiler,siphon and waste water drain pit must be laid at a minimum down slopeof 3° and must be installed in such a way as to prevent any build-up ofcondensate.Fig. 23 Draining the condensate[1] Condensate drain fittingEX: (SB625WS/290)• Boiler pressure = 1.284 inches W.C.• Siphon head = 1.284 inches + 1 inch = 2.28 inches (approx.)5.11.2 Neutralizing the condensateNeutralization unit types NB-5LP, NB-6The NB neutralization unit is designed for systems with boilercondensate drain pits located at a lower level than the boiler condensatedrain fitting. These neutralization units do not require any electricalconnections.TypeDimensionsinch [mm]FittingØNB-5LP 9x36 1/4x7 5/16 (228x921x192) 1”NB-6 12x12x12 3/16 (305x305x306) 1”1/4Table 11 Neutralization unit types NB-5LP, NB-66 720 805 218-22.1TThe inlet fitting of the NB neutralization unit (the lower fitting) must beconnected to the boiler condensate drain fitting.The outlet fitting of the neutralization unit (the top fitting) must beconnected to the boiler room’s waste water drain pit using a section offlexible hose or PVC pipe (not supplied).6 720 805 218 (2013/02)SB625WS/SB745WS