1. Fireplace Inspections Made Easier
1901 N. Moore St.
Arlington, VA 22209
(703)

2. Hearth, Patio & Barbecue Education Foundation
National Fireplace Institute

3. Why discuss fireplace inspections?
Challenges our industry presents
Importance to public safety

4. Challenges Products are Constantly Changing New product offerings
Various installation applications
Venting systems and venting configurations

5. Challenges Variety of Code Issues Combustion air Use of room
Authority for venting instructions
Mobile home requirements

6. Challenges Manufacturers’ Instructions
Installation requirements differ
Manufacturer to manufacturer
Model to model
Inconsistent organization
Inconsistent terminology

7. Challenges
Inspectors
Numerous responsibilities
Lack of time

8. Improper Installation
May result in:
Poor Performance
Voiding of Listing and Warranty
–Assumption of All Liability
Loss of Property and Life

9. Reference Manuals

10. We offer the following Inspection
as a guideline, not as a required
list of inspection areas.

11. Inspection Categorizing Appliances General Concerns Gas Appliances
Wood Burning Appliances
Pellet Appliances
Accessories

12. 1. Categorizing Appliances
Inspection
1. Categorizing Appliances

13. Categorizing Hearth Appliances
Fuel
Type
Appliance Standard
Venting
Method
Appliance Type

14. Categorizing Hearth Appliances
Fuel Type
Gas
Solid Fuel
Electric
Natural Gas
Liquid Propane
Wood
Coal
Biomass

15. Categorizing Hearth Appliances
Appliance Type

16. Masonry Fireplace

17. Factory Built Fireplace

18. Gas Log Sets

19. Fireplace Inserts

20. Free Standing Stoves

21. Hearth Stoves

22. Masonry
Furnaces
Outdoor

23. Categorizing By Venting Type
Gas Venting Systems
Conventional Vent
Direct Vent
Unvented

24. Categorizing By Venting Type
Gas Conventional Vent
Chimneys
Masonry or Factory-Built
B-Vent
Liners

25. Categorizing By Venting Type
Gas Direct Vent
Coaxial
Co-linear
PVC
Hi-efficiency condensing

26. Categorizing By Venting Type
Woodburning Venting Systems
Masonry
Chimneys
Factory-Built
Chimneys
Liners
1700°
2100° “HT”

27. Categorizing By Venting Type
Pellet Venting Systems
Type L Pellet
Pellet DV
Liners

28. Gas Standards Vented Gas Hearth Appliances NOT Efficiency Tested
(“Decorative”)
Efficiency Testing (“Heating”)
Gas Log Sets
Gas Fireplace
Gas Fireplace Heaters

29. Categorizing By Venting Type
Gas Direct Vent
Coaxial
Co-linear
PVC
Hi-efficiency condensing

30. Gas Logs Fireplaces Freestanding Stoves
Gas Standards
Unvented Gas Hearth Appliances
Gas Logs Fireplaces Freestanding Stoves

31. Gas Standards

32. Vented Gas Fireplace ANSI Z21.50, CSA 2.33
Appliances: (Not tested for efficiency)
•Fireplaces
•Fireplace inserts
•Freestanding stoves
Requirements
•Safety pilot
•Spill switch if equipped with draft hood
Restrictions
•No thermostat
Options
•Listed blowers

33. Vented Gas Fireplace Heater
ANSI Z21.88, CSA 2.33
Appliances: (Tested for efficiency)
•Fireplaces
•Fireplace inserts
•Freestanding stoves
Requirements
•Safety pilot
•Spill switch if equipped with draft hood
Restrictions
•None
Options
•Listed blowers
•Thermostats

34. Decorative Gas Accessory in Solid Fuel Fireplaces
Appliances: ANSI Z21.60, CSA 2.26
•Log Sets
Requirements
•Safety pilot
•Working fireplace and chimney
•Permanent damper opening
•Fireplace screen
•Cleaning of venting system
Restrictions
•No thermostat
Options
•Listed blowers

35. Manually Lighted, Natural Gas Appliances for Installation in Solid-fuel Burning Fireplaces
ANSI Z21.84
Appliances:
Log Sets
Requirements
Working fireplace and chimney
Permanent damper opening
Fireplace screen
Cleaning of venting system
Restrictions
No thermostat

36. Unvented Gas Room Heater
ANSI Z a
Appliance s:
•Fireplaces
•Fireplace inserts
•Freestanding stoves
Requirements
•Safety pilot w/ODS
Restrictions
•Bedroom, Bathroom, Confined space
•Tight construction
•Maximum 40,000 Btu/hr input
Options
•Listed blowers
•Thermostats

37. Solid Fuel Standards Underwriter’s Laboratories (UL)
Materials and construction
Fire and strength tests
Review of installation instructions

38. Open Chamber Factory Built Fireplaces
Solid Fuel Standards
Solid Fuel Appliances
Open Chamber Factory Built Fireplaces
Closed Chamber High Efficiency
Fireplace Stoves
High Efficiency Factory Built Fireplaces
Freestanding Stoves
Fireplace Inserts
Hearth Stoves

39. UL 127 Factory Built Fireplaces
Testing requirements for entire system
Fire chamber
Chimney
Roof assembly
Related components

40. UL 127 Factory Built Fireplaces
Standard factory-built chimney test
Sustained temperature of 1000°F
Ten minute test at 1700°F
Optional Type HT test
3 - ten minute tests at 2100°F
Not required for factory-built fireplaces

41. Installation Manual

42. Safety Label

43. Inspection
2. General Concerns

44. Combustibles Combustible: Walls with wood framing
Paper-faced materials
Papered sheetrock (dry wall)
– including fire-rated papered sheetrock
Plaster on wood lath or studs

45. Combustibles Noncombustible Entirely metal Brick Tile Concrete Slate
Plaster on metal lath

46. Safety Testing

47. Clearances

48. Clearances Side Clearance Back Clearance Bottom Clearance
Also mantle, surround, ceiling and adjacent walls

49. Clearances
Header
Size
Orientation
– Flat or on edge

50. Clearances

51. Clearances
Standoffs -Top

52. Clearances
Standoffs -Side

53. Clearances
Standoffs -Bottom

54. Clearances Nailing flanges

55. Clearances Instruction Manual

56. Clearances Instruction Manual

57. Clearances Safety Label

58. Clearances Warning Labels

59. Clearances Warning Labels

60. Clearances Wall Protection
Reducing listed clearances
Approved site-built systems
Listed manufactured systems
Clearance reduction systems can NOT
reduce clearance to less than 12"
Clearances less than 12" can only be listed clearance, specific by manufacturer.

61. Clearances Wall Protection
Ceiling
3½" masonry wall / NO ventilation
33%
½" noncombustible board over 1" insulation, NO ventilation
50%
Min. 24 gage sheet metal / spaced out 1"
66%
3½" masonry wall / spaced out 1"
½" noncombustible wall board spaced
out 1"
Listed prefabricated systems
Manufacturer instructions

62. Clearances Wall Protection 1" air space gives greatest reduction
Converts radiant energy to convection heat
Rising warm air pulls in cool air 12

63. Vent System Purposes Remove combustion by-products
Protect combustibles from heat
Airspace
Remember: combustibles can ignite with no
contact from flame
Obtain adequate combustion air

64. House Pressure Conditions
Sources that exhaust air:
Kitchen range fans
Clothes dryers
Central vacuum
Gas furnace
Water heaters
Recessed lighting
Additional hearth appliances,
-especially open fireplace
Outside air
Open fireplaces require cfm
EPA woodstoves require cfm
4”outside air brings in about 10 cfm of air
Photo compliments of CSIA

65. House Pressure Conditions
House Stack Effect
Heated portion of house taller than vent termination
Open window in upper portion create greater chimney effect than vent 65

66. Combustion Air Combustion Air provided for combustion that air:
(Primary Air)
Air provided for combustion that
mixes with the gas.
Air introduced into draft hood and mixed with flue gases. Moderates draft and reduces vent temperatures
Dilution air:
Excess air:
(Secondary Air)
Air that that does not combine with fuel in the combustion process

67. Combustion Air Air changes per Percent of volume exchanged hour (ACH):
(outdoor air replacing indoor air).
Example: 0.35 ACH = 35% of volume of indoor air is replaced by outdoor air every hour.
Continuous water vapor retarder
Unusually tight Storm windows
construction:
Weather-stripping Caulking/sealing of gaps

68. Confined Space with volume less than
Combustion Air
Confined Space with volume less than
space: 50 cubic feet per 1000 Btu/hr
Unconfined
space:
Space with volume 50 cubic feet or more per 1000 Btu/hr.
Rooms communicating through openings without
doors are part of unconfined space.

69. KAIR Method: Known Air Infiltration Rate
2002 – 2009 Fuel Gas Codes
Combustion Air
KAIR Method: Known Air Infiltration Rate
Air Exchange rate is known
Must be used if .40 or less
May be used if between .40 & .60
Standard Method: Air exchange rate is not known.

70. 2002 – 2009 Fuel Gas Codes KAIR Method
60,000 Btu/hr natural draft gas fireplace in room 15' x 25'
with 9' ceiling in house with 0.40 ACH
Formula:
21 divided by .40 = 52.5 [60,000 divided by 1,000 = 60]
60 x 52.5 = 3,150 cubic feet
Available volume in room: 15 x 25 x 9 = 3,375
Indoor air OK because volume is more than required 3,150 cubic feet

71. 2002 – 2009 Fuel Gas Codes Standard Method
Minimum volume necessary: 39,000 BTU appliance
50 cu. Ft for every 1,000 BTU’s
39,000 BTU’s / 1,000 = 39
39 * 50 = 1950 cu. Ft
Divide input rating Btu/hr by 20
1,000 / 50 = 20
39,000 BTU appliance / 20 = 1950 cu. Ft
Room volume 1,950 or greater is OK
Room volume less than 1,950 is not OK
(I.E. Room size 21x12x8=2016 cubic feet = OK)

72. Standard Method Maximum Btu/hr rating Room15x18x8 = 2,160 cu. Ft
2002 – 2009 Fuel Gas Codes
Standard Method
Maximum Btu/hr rating
Room15x18x8 = 2,160 cu. Ft
50 cu. Ft for every 1,000 BTU’s
2,160 cu. Ft. / 50 = 43.2 (43,200 BTU’s)
Multiply the volume by 20
2,160 cu. Ft. * 20 = 43,200 BTU’s
Space OK for appliance with 43,200 Btu/hr or less Space not OK for appliance with more than 43,200 Btu/hr

73. Combustion Air Bedroom/Bathroom -Unvented Confined space
2002 – 2009 Fuel Gas Codes
Combustion Air
Bedroom/Bathroom -Unvented
Confined space
Not allowed
Unconfined space
1 wall-mounted heater
No more than 6,000 Btu/hr in bathroom
No more than 10,000 Btu/hr in bedroom
2002-> Gas logs allowed with means to mount burner base to floor of solid-fuel fireplace

74. Combustion Air Adjoining Rooms
2002 – 2009 Fuel Gas Codes
Combustion Air
Adjoining Rooms
Minimum free area of 1 sq. in./1,000 Btu/hr
Not less than 100 sq. in.
One opening commences
within 12 in. of ceiling
within 12 in. of floor

75. Combustion Air Different Stories
2002 – 2009 Fuel Gas Codes
Combustion Air
Different Stories
Minimum free area of 2 sq. in./1,000 Btu/hr
Not less than 100 sq. in.

76. Two Openings: Directly or Vertical Ducts
2002 – 2009 Fuel Gas Codes
Combustion Air
Outdoor
Two Openings: Directly or Vertical Ducts
One within 12” of ceiling
One within 12” of floor
can be from ventilated attic
can be from ventilated crawl space
Minimum 1 sq. in. per 4,000 Btu/hr

77. Two Openings: Horizontal Ducts
2002 – 2009 Fuel Gas Codes
Combustion Air
Outdoor
Two Openings: Horizontal Ducts
One within 12” of ceiling
One within 12” of floor
Minimum 1 sq. in. per 2,000 Btu/hr

78. Combustion Air Outdoor One Opening Within 12” of ceiling
2002 – 2009 Fuel Gas Codes
Combustion Air
Outdoor
One Opening
Within 12” of ceiling
Communicates with outdoors
Directly
Through ducts
Spaces that freely communicate with outdoors
Minimum 1 sq.in./3,000 Btu/hr
Not less than sum of areas of all vent connectors

79. 2002 – 2009 Fuel Gas Codes Combustion Air: Summary
Indoor Adjoining room 2 Openings
1 in² per
1,000 BTU’s
12” of ceiling
12” of floor
At least 100 in²
Indoor Different story
2 in² per
Outdoor
Direct or Vertical
2 Ducts
4,000 BTU’s
May be from ventilated attic or
ventilated crawl space
Outdoor Horizontal Ducts 2 Openings
2,000 BTU’s
One Duct or Direct Opening
3,000 BTU’s
Not less than the sum of the areas of all
vent connectors

80. Combustion Air Source of Air
2002 – 2009 Fuel Gas Codes
Including adjacent spaces that cannot be closed off
May now use a combination of
openings to indoor spaces
outdoors

81. Opening Size Calculation
Combustion Air
Opening Size Calculation
60,000 Btu/hr gas fireplace
12 x 15 x 8 room
Determine total room volume: 12 x 15 x 8 = 1,440 cu. ft.
Determine required volume by standard method: 60,000/20 = 3,000 cu. ft required
1440/3000=48% The room is able to provide 48% of the necessary air. We need to bring 52% in from outside.
Determine overall opening size:(1 sq. in/3,000 BTU’s) 60,000/3,000 = 20 sq. In. (1 duct direct to outdoors)
Determine minimum outdoor air opening:
20 x 52% = 10.4 sq. In.

82. Combustion Air Louvers and Grilles Size based on net free area
Wood
Size based on net free area
Calculation
Wood: 25% free area
6"x10" = 60 x .25 = 15 sq. in.
Metal: 75% free area
Metal
Screens: mesh size must
not be smaller than 1/2"
10"x6" = 60 x .75 = 45 sq. in.

83. Combustion Products Vented to Outside
Combustion Air
Direct Vent
Combustion air requirements do NOT apply
Combustion Air from Outside
Combustion Products Vented to Outside

84. Combustion Air Passive: Non-mechanical (no fan) Infiltration
Gaps in building envelope
Outside air kit
May be required
May not be reliable source due to influence of pressure conditions inside and outside house
– Flow reversal of air and combustion products possible in certain situations

85. Combustion Air Outside Air Kits High enough to avoid blockage
– snow, leaves, debris
Never from garage or space where combustible liquids stored
Never from attic or position above flue gas outlet
Duct as short and straight as possible
Follow manufacturer’s instructions for materials,
length, height, location

86. Combustion Air Decorative Fireplaces (UL 127 or UL 737) NFPA 211
Outside air where required by AHJ
Listed component installed to instructions
Not from
Attic
Basement
Garage
Another interior space

87. Combustion Air Decorative Fireplaces (UL 127 or UL 737) IRC
Exterior air supply unless room mechanically ventilated/controlled to neutral or positive pressure
OK from ventilated attic or crawl space
Not From
Garage
Basement
Elevation higher than firebox

88. Combustion Air Powered Make-up Air System
Fan and ductwork to make up difference between available and needed
Specifications determined by house pressure test
Depressurization level from exhaust devices
Hearth appliance tolerance
Avoid bringing in more unheated air than needed

89. Combustion Air Duct heater 24VAC damper Inline fan Outdoor
Weather hood
Diffuser
Interlock and
speed control
Insulated
duct

90. Mobile Home Requirements
HUD Requirements
Outside air attached directly to appliance
Mechanically attached to floor
No installation in sleeping room
Listed chimney with spark arrestor
UL 127 and 1482
Maintain structural integrity of home
Manufacturers’ Instructions
Some require electrical grounding to chassis

91. NFPA 211 Inspections
Definitions
Readily accessible: Exposed for inspection without tools to open or remove doors, panels, coverings
Accessible: Exposed for inspection without doing damage, but may require tools
Non-accessible, concealed:Inspection requires damage to chimney, building structure or finish, and/or use of special tools

92. NFPA 211 Inspections Level 1 Circumstance Level of access
Replacement of connected appliance with one of similar type, input rating, & efficiency
Level of access
Readily accessible portions of chimney exterior & interior; accessible portions of appliance & chimney connection

93. NFPA 211 Inspections Level 1
Scope
Readily accessible areas of chimney, structure, and flue
Lack of obstruction or creosote in flue
Basic appliance installation and connection

94. NFPA 211 Inspections Level 2 Circumstance Level of Access
Addition of appliance
Replacement with appliance of dissimilar type
Sale or transfer of property
Operating malfunction or external event likely to
have caused damage to chimney
Level of Access
Accessible portions of chimney & appliance
Video scanning or other means of inspection

95. NFPA 211 Inspections Level 2 Scope All subjects of level 1
Proper construction and condition of accessible portions of chimney structure and enclosed flues
Size and suitability of flues for connected
appliances

96. NFPA 211 Inspections Level 3 Circumstances
Investigation of incident that has caused damage to the chimney or building
Hazard detected or suspected as a result of level 1 or 2 inspection cannot be fully evaluated without access to concealed areas

97. NFPA 211 Inspections Level 3 Level of access
Internal and external portions of chimney structure, including concealed areas
Removal of building or chimney components
Removal only as needed to gain access to areas subject to inspection

98. NFPA 211 Inspections Level 3 Scope
All subjects of level 1 and 2 inspections
Proper construction and condition of concealed portions of chimney structure and enclosed flues
Proper clearances from combustibles

99. 1 2 3 NFPA 211 Inspections Level Circumstance Level of Access Scope
Replacement with similar type, input, efficiency
Readily Accessible
Obstructions
Deposits 2
Add/replace dissimilar
Sale of property
Malfunction
Accessible
Construction/
condition
Clearances/ suitability 3
Hazard suspected
Need access to concealed areas
Can include
removal of bldg.
/chimney components
Includes access to concealed areas

100. Green Building Codes Define additional approaches to construction
– Referred to as “overlay” or “reach” codes and standards that extend, but do not conflict with basic codes and standards
Direct impact with some hearth products
Indirect or upcoming impact in relationship to air tightness of building envelope or indoor air quality concerns

101. Green Building Codes International Energy Conservation Code
IECC 2009 & IRC 2009
“New wood-burning fireplaces shall have gasketed doors and outdoor combustion air.”
IECC 2012 & IRC 2012
“New wood-burning fireplaces shall have tight-fitting flue damper and outdoor combustion air.”
Section & IRC N
– “Fireplaces shall have gasketed doors.”

102. Green Building Codes International Energy Conservation Code
Material(s) assembled and joined together to provide a barrier to air leakage through the building envelope. An air barrier may be a single material, or a combination of materials.
– Fireplace walls must include an air barrier

103. 3. Gas Appliance Installation Issues
Inspection
3. Gas Appliance Installation Issues

104. Class 4 Condensing Appliances Fireplace, Insert, Stove
Appliance Standards
Z21.60
Gas Log
Sets
Z21.50
Gas
Fireplaces
Z21.88
Gas Fireplace Heaters Z
Unvented Room Heater
Class 4 Condensing Appliances
AFUE
Tested NO
YES
Thermostat
OPTION
Fireplace, Insert, Stove
Vent switch:
Draft hood units
ODS
equipped *
YES

105. Shutoff Valve Exceptions
Readily accessible
Permanently identified
Serves no other equipment
Having direct access without the need of removing or moving any panel, door, or similar cover
Accessible
Having access to but which first requires the removal of a panel, door, or similar covering

106. Shutoff Valve Exceptions
National Fuel Gas Code 2009
“Appliances installed in vented fireplaces and unvented firebox enclosures”
Gas log sets
Fireplace inserts
Unvented hearth appliances
Shutoff valve installed at a manifold
within 50’ of the appliance
Vented fireplaces or free standing hearth appliances require a
shutoff within 6’ of the appliance

107. Shutoff Valve Exceptions
International Fuel Gas Code 2009:
“Vented decorative appliances, room heaters and decorative appliances for installation in vented fireplaces”
Vented gas hearth appliances
Fireplaces
Fireplace inserts
Freestanding hearth appliances
Vented gas log sets
Unvented gas hearth appliances require shutoff within 6’
of the appliance

108. Sediment Traps Installed close to appliance Intercept solid debris to
prevent blockage
Required by some appliance manufacturers
– Prevent rusting and degradation of main burner

109. Appliance Connections
International Fuel Gas Code
Rigid or CSST (2006) = No length limit
Semi-rigid =Maximum 6’
Copper/aluminum tubing
ANSI Z21.24 Listed Connectors
In the same room as the appliance
Length limited to 3’
•Extended to 6’ in 2009
•Protected from physical damage

110. Appliance Connections
Additional IFGC requirements:
Connectors to vented decorative appliances and room heaters can extend through walls, floors, partitions, ceilings
Semi rigid tubing and listed connectors can
extend through protected appliance openings

111. Yellow Flame Combustion
HVAC industry
Yellow flame means inefficiency
Hearth industry
Reduce primary air intake
Use secondary air to achieve acceptable
Combustion efficiency
Flame aesthetics

112. Vented Gas Fireplace Installation Listed to
ANSI Z21.50 Gas Fireplaces
ANSI Z21.88 Gas Fireplace Heaters
Floor Support and Protection:
Most can be installed on combustible surface
Carpet & vinyl usually not approved without metal
or wood panel
Appliance level and plumb, with adequate support
Hearth extension may/may not be required

113. Vented Freestanding Appliance
Floor protection
May indicate installation on solid combustible floor
May indicate bottom heat shield required
May require metal, wood panel, or listed pad
Clearances
Specified from front, sides, rear, corners
Alcove may not be allowed

114. Gas Appliance Venting Systems
Negative Pressure
Category 1 (Natural draft hearth appliances)
No condensate
Category 2
Capable of condensate
Positive Pressure
Category 3
Category 4 (Mechanical draft hi-efficiency hearth
appliances)

115. Conventional Vent Systems Draft Hood
Allows dilution air into venting system
Provides escape of flue gases in event of no draft, back draft, blockage
Reduces temperatures in vent
Reduces vent height affect
– Stronger draft brings in more dilution, not
combustion air

116. Conventional Vent Systems
Type B Vent
Factory-made, double wall metal pipe
Air space between walls
Close clearance
Help maintain draft and reduce condensation

117. Conventional Vent Systems Type B Vent
Components not interchangeable
unless allowed by manufacturer
Hearth products use
Round B vent
Oval B 2x4
Oval B 2x6
NOT Type BW unless otherwise listed
118

118. Conventional Vent Systems
Type B Vent
Horizontal Run and Rise
Minimum vertical height may be specified
Keep horizontal run to minimum
Rise at least ¼ inch per foot for vent or connector
Maximum rise to run ratio
75% of vent height for single wall connector
100% for double wall B vent connector
Manufacturer may require 50% maximum (2:1)

119. Conventional Vent Systems
Type B Vent
Termination with obstructions within 8’
2’ higher than any portion of the building within 8’

120. Conventional Vent Systems
Type B Vent
Common Venting
Appliances on different floors of building
Only allowed for appliances in areas
separate from living space
Appliances on same floor
Not addressed or prohibited
Appliance manufacturer may prohibit
AHJ may prohibit

121. Conventional Vent Systems
Type B Vent
Chimney Liners
Required for gas fireplace inserts and freestanding appliances using masonry or factory-built chimneys
Listed liner systems
Type B vent listed to UL 1777
Aluminum or stainless steel UL 1777
Rigid or flex

122. Conventional Vent Fireplace Insert
Fireplace and chimney in good working order
Some require hearth extension protection
Alterations: variations by manufacturer
Required removal of damper and grate
Refractory, smoke shelf, baffles, screen, doors can be removed
Insulation can NOT be removed

123. be required for air circulation and cooling
Conventional Vent
Fireplace Insert
Surround variations
Gap between fireplace face and panel may
be required for air circulation and cooling
Insulation along top of insert may be required for mantel clearances
May allow installation without panel if minimum
gap with mesh maintained
Air inlet grilles on factory-built fireplaces important consideration

124. Conventional Vent Condensing Appliance Plastic Pipe (PVC)
Recognized in Fuel Gas Codes
– Appliances must be listed for use
High efficiency, Category IV
Resists corrosion from condensation
Provides adequate heat protection
Can be sealed for mechanical vent positive
pressure

125. Direct Vent

126. Direct Vent Follow manufacturer instructions
Venting
Clearances
Vent system is part of appliance
Appliance manufacturer provides instructions
Permissible configurations are model
specific

127. Direct Vent

128. Direct Vent

129. Direct Vent

130. Direct Vent Fireplace Inserts

131. Direct Vent Fireplace Inserts
Air intake terminated above damper inside chimney
Listing and instructions
Must be in instructions
May require blocking of damper area

132. Direct Vent Condensing Appliance
Direct Vent PVC Systems
Provides outside combustion air
Co-linear
Two separate PVC pipes
Co-axial
Inner pipe expelling exhaust
Space between pipes providing combustion air

133. Mechanical Vent Systems
Negative pressure (B-Vent or Direct Vent)
Fan at flue collar or termination of vent
Positive pressure (Direct Vent only)
Fan before the firebox
© Central Fireplace
© Empire Comfort Systems

134. Unvented

135. Unvented ODS Pilot: Oxygen Depletion Shutdown
Normal Operation % Oxygen
Oxygen Level Dropping 19% Oxygen
Safety System 18% Oxygen
Pilot flame engulfs tip of thermocouple
Flame begins to lift off
Thermocouple
begins to cool
Unstable flame moves away from thermocouple Thermocouple stops generating sufficient mv to keep valve open
Flow of gas stops

136. Unvented NFGC & IFGC IFGC Combustion air requirements
Use of room restrictions
IFGC
Maximum input rating of 40,000 Btu/hr
Not to be sole source of heating in house

137. Fuel Conversion Some appliances, including unvented, can
NOT be field converted
Others specify in instructions
May required approved conversion kit
Label identifying fuel attached to control valve

138. QUESTIONS?
THANK YOU FOR YOUR ATTENTION