Furnace

FURNACE

• A valid permit and plans must be on-site R106.3.1
• Manufacturer’s instructions must be left with the unit CRC R106.2
• Design, construction, and workmanship shall comply with accepted engineering practices and shall be of such character as to secure the results sought to be obtained by this code. CMC 309

Gas

• EQ valve with gas line change CPC 1211.7 
• Sediment trap: (3” – see photos) and CPC 1212.9
• Gas test after S/R (gas line drawing) and CPC 1213.3
• Gas shut-off: at appliance upstream from flex 6’ CPC 1212.5
• Cap unused gas lines CPC 1206.3
• Pipe strapped: see plumbing and CPC 313

Combustion Air/Venting (BTU/20 or 50cu ft/1,000 Btu/h) CMC 701

• Direct Vent: all air for combustion must be derived directly from outdoors CMC definitions
• Where the vent connector used for an appliance having a draft hood or a Category 1 appliance is located in or passes through an unconditioned area, attic, or crawl space, that portion of the vent connector shall be listed Type B, Type L CMC 802.10.1.1
• Combustion air: (upper and lower – commence within 12” top and bottom – horizontal ducting + 2X size) CMC 701.4
• PVC vent: must have contrasting colored primer – 2% slope back to unit – length, and # of fittings per MI and CMC 802.4.2
• Combustion air from the attic: – no screen on the vertical opening CMC 701.11(5)
• Louvers: metal minus 25% wood 75% – motorized = interlock – (25 sq in/0.75) CMC 701.10
• Venting/Termination: CMC 802.5.4
• B-vent:
  • No screws or tape CMC 802.6
  • Clearance: 1” to combustibles per listing – Single wall 6” CMC 802.7.3.4
  • One offset ≤ 60° from vertical. Total horizontal offset = 75% of the total height. CMC 802.6.3.2
  • Connector: 1:1 ratio vertical to horizontal. No dips or sags. CMC 802.10.7.2
• Vent Connector: Max Horizontal Length CMC 803.2.1
  18″ in length per inch in diameter
  Diameter Max Length
  3″—————-4.5′
  4″—————-6′
  5″—————-7.5′
  6″—————-9′
  7″—————-10.5′
  8″—————-12′

General

• Manufacturer’s instructions left with the unit CPC 507.24
• Mini Splits: disconnecting means must be adjacent and in sight of equipment. or circuit breaker lot out installed CEC 440.14
• Clearances: upright 5’ CMC 904.10 and MI – horizontal MI
• Garage installation: 18” and protection from damage CMC 305
• Bedroom/bath installation: listed, self-closing, gasketed, exterior combustion air – direct vent units are exempt CMC 904.1(1-2) 
• Condensate drain: see condensates
• Secured: CMC 303.4 and MI
• New furnace in CS/Basement with < 2 x 10 joists = Sheetrock on the underside of the crawl space floor joists for the room footprint above the furnace only per the BO. CRC 302.13.
  • 6” clearance below the hanging unit
  • This now includes all electrical and gas appliances
  • Sheetrock must be water-resistant or painted per the BO
  • Like-for-like replacements are exempt – this means the same type of device in the same location
• 24” wide walking path in the attic. Length of the passage: < 6’ in height  20’ max length CMC 304.4.1
• 22 x 30 access (crawl space same)
• 30 x 30 working space CMC 304.4.3
• Ducting insulation CMC 604
• Service light and outlet CMC 304.4.4
• Ducting support (no sags) CMC 603.8 and MI 
• Clearance from fire box to rafters in attic CMC 904.2 and MI
• Pan if water damage is possible (see condensates) and CMC 310.2
• Ducts penetrating garage wall to living space 26ga metal R302.5.2
• Building > 15’ = interior ladder CMC 304.3.1
• Smoke detector required (factory installed) in supply duct for > 2,000 cfm 
• Air balance report CMC 407.3.1
• Furnace platforms for plenums must now be sealed sheet metal

Wall Furnace CMC 907

• No offset in the wall
• 12’ min rise of the vent above the bottom of the wall furnace
• Attic insulation shield
• First set of double top plates, spacer only, all others get fire stop plates
• Cut double top plates flush with studs

Electrical

• All work done in a neat, workmanlike manner CEC 110.12
• Dedicated circuit required CEC 422.12
• Type S fuse MI
• Check nameplate for max over-current fuse (SSU)
• Hardwired disconnect within sight and dedicated CEC 422.31
• The panel must be labeled CEC 110.22.A
• Breakers match panel mfg or certified replacement CEC 110.3.B
• Service receptacle within 25’ and in sight CEC 210.63 and CMC 304.4.4