CPA Wall Furnace
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FURNACE (WALL)
City of Palo Alto (CPA)
Building Inspection Division
285 Hamilton Ave.
Inspection Request: 650 329-2496
Building Division
Revision Date: 03/04/11
General Requirements/Checklist for:
Residential
Codes Enforced:
2010 CRC, CBC, CMC,CEC,CPC
Palo Alto Municipal Code (PAMC)
IVR# 609
The information provided in this document is general and intended as a guide only. Each project is unique and
additional requirements may be enforced as deemed appropriate.
WARNING
 Failure to complete items below, prior to inspection, may result in a re-inspection fee.
GREEN BUILDING TIPS *Rebate www.cityofpaloalto.org/smartenergy
 *Energy Star gas furnace saves as much as 20% annually on your total energy cost.
 Replacement of vented wall furnaces of the same or less BTU input may be installed in
the same location if it doesn’t create an unsafe condition.
 Recommendation: do not install wall furnace on exterior wall. Install on interior wall
for maximum efficiency.
 All wall furnaces must be installed in accordance with manufacturer’s instructions and
local requirements.
 CPA INSPECTION
 provide inspector with manufacturer’s instruction manual & access to attic during
inspection. CMC 108.4
Clearances
 minimum 12” inches from door swing
 minimum 4” inches from wall
 minimum 6” inches from inside corner (unless listed for less)
 minimum 18” inches below any structural projection
( including doors and windows that would project over
the furnace.) See figure 805 (a)-1 and 805 (a)-2
Combustion Air
 Vented wall furnaces shall be provided with combustion air per CMC chapter 7.
(exception: combustion air openings may be omitted to an area in which a vented wall
furnace is installed, provided there is a permanent case opening into other rooms
having a combustion volume of 50 cubic feet per 1000 BTU. limitations: ducts shall not
be attached to wall furnace. CBC 701.0 See Figure 805 c-1
CPA Wall Furnace
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Venting
 Gas appliance Vents shall be installed per Chapter 8 of the 2007 California
Mechanical Code. Vents that pass through unconditioned areas such as attic, roofs,
underfloor, and unconditioned basements shall be listed Type B or Type L double wall
vents and shall have a minimum 1” inch clearance to combustibles. Single wall vents
are not allowed. CMC 802.10.2
 One story or top story of multistory installation: install 26 gage metal sleeve open and
extending into attic 12” inches or 2” from roof sheathing. Ceiling plate spacer (not firestop spacer) to ventilate stud above base plate at first header only. See figure 907-1
 Listed BW gas vent outlet shall terminate a minimum of 12’ feet in vertical height
above bottom of wall furnace. CMC 802.6.2.2
 Vents shall be attached to a solid header plate designed for the vented wall furnace.
Note: 1 strap per plate with a minimum of 14 nails each side shall be installed to any
bearing wall. CMC 928.1 by listing
 Stud spaces in which type BW vent are installed shall be free of any obstructions and
be cut flush with the adjacent stud walls.
 Clearances of type BW vents shall be maintained by the base & ceiling plates spacers
strap of fire stop space. See figure 9-2, 928.1 c
 Type BW gas vents listed for only single story buildings are allowed only in single story
buildings or the top floor of multi story buildings. note: BW vents listed for multi-story
use may be installed in single or multi story buildings.
 Stud space that contains a type BW gas vent in a single story and the top story of multi
story building shall be open to the attic and supplied with a storm collar. fire stop
spacers are required at the ceiling plate. CMC 928.1 c
 Stud spaces shall be vented at the first ceiling plate above the furnace. CMC 928.1 c
 A suitable metal guard (16 gage) shall be installed at each floor level.
 BW vent installed in an existing building shall be completely open for installation and
inspection.
 Vents shall extend from the header plate through the roof with out offsets or
crossover. See figure 907-1, 903 (a)-3, 903(a)-4 and 907-2
 Gas line air test required when any modifications are made to gas line piping,
excluding gas connector. If applicable see “Whole House Gas Test” for testing
guidelines. CPC 1214.5
 Gas connector shall be rated/sized for load/demand of the furnace; shall not pass
through any walls, partitions, ceilings, floors or concealed space; connector shall not
exceed 3’ feet in length; and the existing old connector shall not be reused when
replacing the furnace. DO NOT REMOVE SIZING LABLE FROM CONNECTOR,
INSPECTOR MUST VERIFY. CMC 1312.1 (d)
NOTE: Wall furnace located in structural walls may require PA heavy gauge
metal straps to maintain load transfer capacity @ double top plates.