Fireplace Inspections Made Easier
1901 N. Moore St.
Arlington, VA 22209
(703) 524-8030
Hearth, Patio & Barbecue
Education Foundation
National Fireplace Institute
Why discuss fireplace inspections?
• Challenges our industry presents
• Importance to public safety
Challenges
Products are Constantly Changing
• New product offerings
• Various installation applications
• Venting systems and venting configurations
Challenges
Variety of Code Issues
•
•
•
•
Combustion air
Use of room
Authority for venting instructions
Mobile home requirements
Challenges
Manufacturers’ Instructions
• Installation requirements differ
– Manufacturer to manufacturer
– Model to model
• Inconsistent organization
• Inconsistent terminology
Challenges
Inspectors
• Numerous responsibilities
• Lack of time
Improper Installation
May result in:
• Poor Performance
• Voiding of Listing and Warranty
–Assumption of All Liability
• Loss of Property and Life
Reference Manuals
We offer the following Inspection
as a guideline, not as a required
list of inspection areas.
Inspection
1. Categorizing Appliances
2. General Concerns
3. Gas Appliances
4. Wood Burning Appliances
5. Pellet Appliances
6. Accessories
Inspection
1. Categorizing
Appliances
Categorizing Hearth Appliances
Hearth Appliances
Fuel
Type
Appliance Type
Appliance
Standard
Venting
Method
Categorizing Hearth Appliances
Fuel Type
Gas
Natural Gas
Solid Fuel
Liquid Propane
Electric
Wood
Coal
Biomass
Categorizing Hearth Appliances
Hearth Appliances
Appliance Type
Masonry Fireplace
Factory Built Fireplace
Gas Log Sets
Fireplace Inserts
Free Standing Stoves
Hearth Stoves
Masonry
Furnaces
Outdoor
Categorizing By Venting Type
Gas Venting Systems
Conventional Vent
Direct Vent
Unvented
Categorizing By Venting Type
Gas Conventional Vent
B-Vent
Chimneys
Masonry or Factory-Built
Liners
Categorizing By Venting Type
Gas Direct Vent
Coaxial
Co-linear
PVC
Hi-efficiency condensing
Categorizing By Venting Type
Woodburning Venting Systems
Masonry
Chimneys
Factory-Built
Chimneys
1700°
Liners
2100° “HT”
Categorizing By Venting Type
Pellet Venting Systems
Type L Pellet
Pellet DV
Liners
Gas Standards
Vented Gas Hearth Appliances
NOT Efficiency Tested
(“Decorative”)
Gas Log Sets
Gas Fireplace
Efficiency Testing
(“Heating”)
Gas Fireplace Heaters
Categorizing By Venting Type
Gas Direct Vent
Coaxial
Co-linear
PVC
Hi-efficiency condensing
Gas Standards
Unvented Gas Hearth Appliances
Gas Logs
Fireplaces
Freestanding Stoves
Gas Standards
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
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
Decorative Gas Accessory in
Solid Fuel Fireplaces
ANSI
Z21.60,
CSA2.26
Appliances:
•Log Sets
Requirements
•Safety pilot
•Working fireplace and chimney
•Permanent damper opening
•Fireplace screen
•Cleaning of venting system
Restrictions
•No thermostat
Options
•Listed blowers
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
Unvented Gas Room Heater
Appliances:
ANSI Z21.11.2a
•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
Solid Fuel Standards
• Underwriter’s Laboratories (UL)
– Materials and construction
– Fire and strength tests
– Review of installation instructions
Solid Fuel Standards
Solid Fuel Appliances
Open Chamber
Factory Built
Fireplaces
Freestanding
Stoves
Closed Chamber
High Efficiency
Hearth Stoves
Fireplace Stoves
Fireplace
Inserts
High Efficiency
Factory Built
Fireplaces
UL 127 Factory Built Fireplaces
• Testing requirements for entire system
– Fire chamber
– Chimney
– Roof assembly
– Related components
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
– Sustained temperature of 1000°F
– 3 - ten minute tests at 2100°F
– Not required for factory-built fireplaces
Installation Manual
Safety Label
Inspection
2. General Concerns
Combustibles
• Combustible:
– Walls with wood framing
– Paper-faced materials
• Papered sheetrock (dry wall)
– including fire-rated papered sheetrock
– Plaster on wood lath or studs
Combustibles
• Noncombustible
– Entirely metal
– Brick
– Tile
– Concrete
– Slate
– Plaster on metal lath
Safety Testing
Clearances
Clearances
•
•
•
•
Side Clearance
Back Clearance
Bottom Clearance
Also mantle, surround,
ceiling and adjacent walls
Clearances
• Header
• Size
• Orientation
– Flat or on edge
Clearances
Clearances
Standoffs -Top
Clearances
Standoffs -Side
Clearances
Standoffs -Bottom
Clearances
Nailing flanges
Clearances
Instruction Manual
Clearances
Instruction Manual
Clearances
Safety Label
Clearances
Warning Labels
Clearances
Warning Labels
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.
Clearances
Wall Protection
Protection
Wall
Ceiling
3½" masonry wall / NO ventilation
33%
½" noncombustible board over 1"
insulation, NO ventilation
50%
33%
Min. 24 gage sheet metal / spaced out 1"
66%
50%
3½" masonry wall / spaced out 1"
66%
½" noncombustible wall board spaced
out 1"
66%
Listed prefabricated systems
50%
Manufacturer instructions
Clearances
Wall Protection
• 1" air space gives greatest reduction
– Converts radiant energy to convection heat
– Rising warm air pulls in cool air
12
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
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 200-300 cfm
• EPA woodstoves require 11-32 cfm
• 4”outside air brings in about 10 cfm of air
Photo compliments of CSIA
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
Combustion Air
Combustion Air provided for combustion that
air: mixes with the gas.
(Primary Air)
Air introduced into draft hood and
Dilution air: mixed with flue gases. Moderates
draft and reduces vent temperatures
Excess air: Air that that does not combine with
(Secondary Air)
fuel in the combustion process
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
Combustion Air
Confined Space with volume less than
space: 50 cubic feet per 1000 Btu/hr
Unconfined Space with volume 50 cubic feet or
space: more per 1000 Btu/hr.
Rooms communicating through openings without
doors are part of unconfined space.
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.
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 0.40ACH
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
2002 – 2009 Fuel Gas Codes
Standard Method
Minimum volume necessary: 39,000 BTU appliance
1.
2.
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)
2002 – 2009 Fuel Gas Codes
Standard Method
Maximum Btu/hr rating
Room15x18x8 = 2,160 cu. Ft
1. 50 cu. Ft for every 1,000 BTU’s
2,160 cu. Ft. / 50 = 43.2 (43,200 BTU’s)
2. 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
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
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
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.
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
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
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
2002 – 2009 Fuel Gas Codes
Combustion Air: Summary
Indoor
Adjoining room
2 Openings
Indoor
Different story
Outdoor
Direct or Vertical
2 Ducts
Outdoor
Horizontal Ducts
2 Openings
Outdoor
One Duct or
Direct Opening
1 in² per
1,000 BTU’s
2 in² per
1,000 BTU’s
1 in² per
4,000 BTU’s
1 in² per
2,000 BTU’s
1 in² per
3,000 BTU’s
12” of ceiling
12” of floor
At least 100 in²
At least 100 in²
May be from ventilated attic or
ventilated crawl space
12” of ceiling
12” of floor
12” of ceiling
12” of floor
Not less than the sum of the areas of all
vent connectors
2002 – 2009 Fuel Gas Codes
Combustion Air
Source of Air
•
•
Including adjacent spaces that cannot be closed off
May now use a combination of
– openings to indoor spaces
– outdoors
Combustion Air
Opening Size Calculation
60,000 Btu/hr gas fireplace
12 x 15 x 8 room
1. Determine total room volume: 12 x 15 x 8 = 1,440 cu. ft.
2. Determine required volume by standard method:
60,000/20 = 3,000 cu. ft required
3. 1440/3000=48% The room is able to provide 48% of the
necessary air. We need to bring 52% in from outside.
4. Determine overall opening size:(1 sq. in/3,000 BTU’s)
60,000/3,000 = 20 sq. In. (1 duct direct to outdoors)
5. Determine minimum outdoor air opening:
20 x 52% = 10.4 sq. In.
Combustion Air
Louvers and Grilles
Wood
• Size based on net free area
– Calculation
• Wood: 25% free area
• Metal: 75% free area
6"x10" = 60 x .25 = 15 sq. in.
• Screens: mesh size must
not be smaller than 1/2"
Metal
10"x6" = 60 x .75 = 45 sq. in.
Combustion Air
Direct Vent
Combustion air requirements do NOT apply
Combustion Air
from Outside
Combustion
Products
Vented to
Outside
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
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
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
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
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
Combustion Air
Duct
heater
Diffuser
24VAC
damper
Inline
fan
Interlock and
speed control
Insulated
duct
Outdoor
Weather hood
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
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
NFPA 211 Inspections
Level 1
• Circumstance
– 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
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
NFPA 211 Inspections
Level 2
• Circumstance
– 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
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
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
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
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
NFPA 211 Inspections
Level
Circumstance
1
Replacement with
similar type, input,
efficiency
2
Add/replace dissimilar
Sale of property
Malfunction
3
Hazard suspected
Need access to
concealed areas
Level of Access
Scope
Readily Accessible
Obstructions
Deposits
Accessible
Construction/
condition
Clearances/
suitability
Can include
removal of bldg.
/chimney
components
Includes access
to concealed
areas
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
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 402.4.1.1 & IRC N1102.4.1.1
– “Fireplaces shall have gasketed doors.”
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
Inspection
3. Gas Appliance
Installation Issues
Appliance Standards
Z21.60
Gas Log
Sets
Z21.50
Gas
Fireplaces
NO
NO
YES
NO
NO
NO
YES
YES
OPTION
Fireplace,
Insert,
Stove
NO
YES
YES
YES
YES
Vent switch:
Draft hood
units
NO
YES
YES
NO
NO
*
NO
NO
YES
YES
NO
AFUE
Tested
Thermostat
ODS
equipped
Z21.88
Gas
Fireplace
Heaters
Z21.11.2
Unvented
Room
Heater
Class 4
Condensing
Appliances
YES
Shutoff Valve Exceptions
• Readily accessible
• Permanently identified
• Serves no other equipment
Readily accessible
– 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
Shutoff Valve Exceptions
•
National Fuel Gas Code 2009
1. “Appliances installed in vented fireplaces and
unvented firebox enclosures”
•
•
•
Gas log sets
Fireplace inserts
Unvented hearth appliances
2. 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
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
Sediment Traps
• Installed close to appliance
• Intercept solid debris to
prevent blockage
• Required by some
appliance manufacturers
– Prevent rusting and
degradation of main burner
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
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
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
Vented Gas Fireplace
• Listed to
Installation
– 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
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
Gas Appliance Venting Systems
• Negative Pressure
– Category 1 (Natural draft hearth appliances)
• No condensate
– Category 2
• Capable of condensate
• Positive Pressure
– Category 3
• No condensate
– Category 4 (Mechanical draft hi-efficiency hearth
appliances)
• Capable of condensate
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
Conventional Vent Systems
Type B Vent
• Factory-made, double wall metal pipe
• Air space between walls
– Close clearance
– Help maintain draft and reduce condensation
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
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)
Conventional Vent Systems
Type B Vent
Termination with obstructions within 8’
2’ higher than any portion of the building within 8’
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
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
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
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
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
Direct Vent
Direct Vent
• Follow manufacturer instructions
– Venting
– Clearances
• Vent system is part of appliance
• Appliance manufacturer provides
instructions
• Permissible configurations are model
specific
Direct Vent
Direct Vent
Direct Vent
Direct Vent
Fireplace Inserts
Direct Vent
Fireplace Inserts
• Air intake terminated
above damper inside
chimney
– Listing and instructions
– Must be in instructions
– May require blocking of
damper area
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
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
Unvented
Unvented
ODS Pilot: Oxygen Depletion Shutdown
Normal Operation
20.9% Oxygen
Pilot flame engulfs tip
of thermocouple
Oxygen Level Dropping
19% Oxygen
Flame begins to lift
off
Thermocouple
begins to cool
Safety System
18% Oxygen
Unstable flame
moves away from
thermocouple
Thermocouple stops
generating sufficient
mv to keep valve
open
Flow of gas stops
Unvented
• NFGC & 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
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
QUESTIONS?
THANK YOU FOR YOUR
ATTENTION