Boiler Manual - Weil-McLain

GV90+ gas-fired water boiler — Boiler ManualVenting & air — general (continued)Manifolded combustion airoption for DIRECT VENTmultiple boiler installationsFigure 37 Combustion air manifold option (combined air inlet, butindividual vents) — must comply with Figure 41, page 351. Multiple GV90+ boilers can use a common combustionair manifold.a. The combustion air inlet must be located in asidewall (and the vents must terminate on thesame side of the building).b. See below for minimum cross sectional area ofcombined air ducts.c. Provide minimum clearance to adjacent ventsand grade/snow line as shown in Figure 37.d. Provide minimum free area in duct (adjustedfor louver restriction) of 1 square inch per2,000 Btuh total boiler input.e. If combustion air damper is used, wire to boilersto prevent operation except after damperhas opened.ONLY air piping can be combined. DONOT use combined vent piping. Allvent pipes must be routed and terminatedindividually as described inthis manual. Flue gas leakage and boilercomponent damage can occur. Failure tocomply could result in severe personalinjury, death or substantial propertydamage.Figure 38 Maintain clearances and placement between the airmanifold inlet and any appliance vent as shown belowAir manifold sizing1. See Figure 110, page 102 for minimum cross sectionalarea of combined air ducts.OR2. CALCULATE required cross section (for area insquare inches):a. MIN. AREA = TOTAL MBH INPUT DIVIDEDBY 23. Example:a. A multiple boiler system with (4) GV90+5boilers has a total input of 4 x 140 = 560 MBH(560,000 Btuh).b. The required duct cross sectional area is:c. MIN. AREA = 560 DIVIDED BY 2= 280 sq. inchesThe air manifold inlet of GV90+ boilers is part of direct vent connections. It is not classified as a forced air intakewith regard to spacing from adjacent boiler vents. To avoid recirculation, however, you must install the vent terminationsand air inlets with the clearances specified in Figure 38, page 31. The vent must be located following therestrictions shown in Figure 41, page 35. The vent termination configuration can be any of the sidewall methods(NOT VERTICAL) shown in this manual for direct vent or direct exhaust sidewall termination installations. THEVENTS MUST BE TERMINATED THROUGH THE SAME SIDE WALL AS THE AIR MANIFOLD INLET.Part number 550-142-054/1211 31