Specifications - City of Montpelier, Vermont

Title:Montpelier District HeatingCity of Montpelier, VT15891 – Metal Ductwork & AccessoriesIssue Date:September 28, 2012Page #:6 of 19larger and are 20 gauge or less, with more than 4 sq. ft. of unbraced panel area, asindicated in SMACNA “HVAC Duct Construction Standard,” Figure 29,regardless of insulation.E. Fabricate elbows, transitions, offsets, branch connections, and other ductconstruction in accordance with SMACNA “HVAC Metal Duct ConstructionStandard, Third Edition (2005)”, Figures 41 through 49, with the followingmodifications:1. Figure 42a. Type RE1 – Square throat is not permitted.b. Types RE4, 6, 7, 8, 9, & 10 are not permitted.2. Figure 43a. Use single thickness vanes with trailing ends, SP=1½”.3. Figure 47a. Offset types 1& 2 are not allowed.b. Minimum bell mouth radius shall be 1½”.4. Figure 48a. Figures A & C are not allowed.F. Fabricate duct fittings to match adjoining ducts, and to comply with ductrequirements as applicable to fittings. Limit angular tapers to 30° for contractingtapers and 20° for expanding tapers.G. Fabricate ductwork with accessories installed during fabrication to the greatestextent possible.H. Duct joining system shall be Ductmate, Nexus, Quicduc, Transverse DuctConnection (TDC), or PyramidLok for all ducts with longest side over 24".Above systems are optional for smaller duct systems. Above systems are to beused with galvanized sheet steel and aluminum sheet. Ducts fabricated ofstainless steel shall have welded joints.I. Button punch snap lock (figure 22, type L2) and internal standing seam joints(figure 27) are not allowed.METAL DUCTWORK AND ACCESSORIES 15891 6