Heating Furnace, Gas: Defects List & Home Inspection Education

Gas fired heating furnace inspection points, defects
Lists of important defects for residential buildings
What does a home inspector need to know? Home inspection training and education curriculum recommendations
BUILDING DEFECTS LISTS - separate article
Questions & Answers about home & building inspection courses, standards, & defect checklists for gas heat furnaces
References

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This article lists significant gas fired heating furnace defects, definitions, and home inspection education topics. This article series, beginning at BUILDING DEFECTS LISTS, provides lists of common building defects and basic defect knowledge that also outline recommended curriculum content for home inspector education. The building defects and inspection points listed in these articles also guide homeowners and home buyers to building areas that merit careful attention and often point areas of safety concern or important maintenance and repair tasks. Page top illustration of a gas fired furnace courtesy of Carson Dunlop Associates.

Home Inspection Education Curriculum - Heating, Gas Furnaces

4. HEATING, Gas Fired Furnaces Inspection Recommendations & Typical Defects Lists

4.1 Gas Fired Warm (or Forced air? Here “warm air” is a gravity furnace) Air Furnaces

4.1.1 Knowledge Base for inspecting gas fired heating furnaces

1. Describe the function of residential heating systems.

2. Describe the common heating fuels (gas, oil, propane, electricity, wood).States GAS above ??

3. Describe the combustion process with reference to the fire triangle, combustion air, ignition, and venting.

4. Describe three methods of heat transfer(radiation, convection, conduction) and how each apply to residential heating systems.

5. Describe the common visually detectable defects in gas fired heating systems and identify safety hazards

6. Describe the common types of heating equipment (furnaces, hot water boilers, steam boilers, space heating, radiant heating).

7. List the materials, function and location for the components of a gas fired forced air furnace including ? fuel delivery system, burner, gas valve, pilot light, thermocouple, combustion air supply, heat exchanger, cabinet, fan (blower, air handler), fan control, high temperature limit switch, thermostat, draft hood, vent connector (exhaust flue, C-vent, B-vent, vent pipe, stack pipe, flue pipe, chimney connector, breeching), filter, electronic air cleaner, humidifier, duct system, registers, grill, induced draft fan, electronic ignition system, condensate handling system, vent damper.

8. Differentiate between conventional, mid efficiency and high efficiency gas furnaces. Include a description of the normal operating cycle for each.

9. Describe the features of adequate installation and repair technique for gas fired forced air furnaces.

10. Define the following terms with respect to gas fired heating systems: gas pressure regulator, gas meter, drip leg(dirt pocket), flex connectors, combustion air, draft air, dilution air, circulating air, spillage(back drafting, down drafting), natural gas, BTU content of natural gas, monoport burner, multi port burner, cross over igniter refractory (firepot), ,(Norrmally only in oil fired systems) JDG gas valve, pilot light, thermocouple, fan/limit switch, heat shield(flame roll out shield), heat exchanger, indirect fired system, direct fired system, draft hood, blower(house fan, furnace fan, air handler, furnace blower), Fan door safety relay..JDG, up flow furnace, down flow furnace, horizontal furnace, summer switch, fan compartment interlock switch, thermostat, heat anticipator, vent connector, supply plenum, return plenum, filter, supply duct system, return duct system, supply registers, return grills, electronic air cleaner, humidifier, input capacity, output capacity, bonnet capacity, steady state efficiency, seasonal efficiency, steady state losses, off cycle losses, stack effect, AFUE, separation of circulating and combustion air.

11.Define the following terms with respect to mid and high efficiency gas furnaces: vent damper, intermittent pilot, direct spark ignition, hot surface ignition, flame rectification, natural draft burners, induced draft burners, forced draft burners, pre-purge, side wall venting, sealed combustion, direct vent, mid efficiency, high efficiency, condensing furnaces, latent heat of vaporization, neutralizer, differential pressure switch, heat switch(spillage switch), blower cover interlock, pulse combustion, combination furnaces(water heater and furnace), tempering valve (mixing valve).

12. Outline the life expectancies for gas fired forced air furnaces.

13. Identify the codes and standards which apply to gas fired appliances and warm air heating systems in your area.

4.1.2 Inspection Skills for Gas Fired Heating Furnaces - Warm Air Heat

1. Describe the inspection procedure for conventional, mid efficiency and high efficiency, forced air gas furnaces.

2. Identify the following common defects listed on the next page.

3. Describe the implication of each defect.

4. Identify safety issues for the inspector and occupant of the house (gas explosion, carbon monoxide poisoning, injury due to moving parts).

5. Communicate findings to client verbally and in writing, recommending corrective action where needed.

List of Typical Gas Fired Heating Furnace Defects

Combustion Air Hazards

Possible or obvious inadequate combuation air
Missing CO or Smoke Detectors

Gas Burners & Venting, Typical Defects at Gas Fired Heating Furnaces

Gas meters - general gas supply piping, regulators, controls

Gas regulators & control valves at the heating equipment

• Gas shut off and locked

• Loose

• Ice

• Missing

• Leaks

• Rust

• Mechanical damag

• Scorched

• Poor access

• Poor location

Heat shield defects at the gas burner - burns, rust, missing, damaged, leaks

Evidence of dangerous conditions

Soot - Carbon Monoxoide fatality risk warnings

flame leakage

rust or water or mechanical damage

Gas Furnace Venting Defects & Hazards

• Rust

• Undersized

• Connector extends too far in chimney

• Draft hood spillage or backdrafting

Gas Piping Defects

• Improper material

• Inadequate combustible clearance

• Copper tubing not properly labeled • Poor manifolding

• Improper connections

• Poor slope

• Inadequate support

• Poor support

• Inappropriate materials

• Poor connections

• Leak

• Rust, dirty, obstructed

• Missing shut off valves

• Vent connector too long

• No drip leg

• Vent connector too big or too small

• Piping in chimney or duct systems

• Plastic pipe exposed above grade

Mid & High Efficiency Gas Furnace Defects

• Rust Corrosion. JDG

• Airflow proving switch problems

Combustion Air Defects at Gas Fired Heaters

• Condensate problems

• Electronic ignition problems

• Inadequate combustion air

• Excess temperature rise

• Heat exchanger problems

Gas Burner Defects at Gas Furnaces

• Induced draft fan problems

• Poor vent location, arrangement

• Delayed ignition

• Poor combustion air intake location

• Dirt or soot

• Spillage switch problems

• Flame wavers when fan comes on

• Vent damper stuck

• Gas odor or leak

• Inoperative

• Poor flame color or pattern

• Rust Corrosion..JDG

• Scorching

• Short cycling

Warm Air (Forced Air) Heating Furnaces, Gas Fired: Defects

Heat Exchanger Defects

• Cracks, holes or rust

• Excess temperature rise

• Soot or deposits

Mechanical Air Filter Defects

• Dirty

• Installed backwards

• Loose or collapsed

• Missing

• Wrong size

Electronic Air Cleaner / Filter Defects

• Damaged cells

• Dirty

• Improper orientation

• Inoperative

• Mis-wired

• Missing components

Air Handler Cabinet Defects

• Combustible clearances

• Mechanical damage

• Missing components

• Obstructed air intake

• Rust

• Scorching

Thermostat Defects for Forced Air Gas Fired Heating Systems

• Anticipator problems

• Damaged

• Dirty

• Loose

• Not level

• Poor adjustment or calibration

• Poor location

Humidifier Defects on Forced Air Gas Fired Heating Systems

• Clogged pad, mesh or nozzle

• Dirty

• Inoperative motor or solenoid valve

• Leaks

• No duct damper

• Poor location

Blower Assembly Defects on Forced Air Gas Fired Heating Systems

• Dirty

• Fan belt loose, worn, damaged

• Inoperative

• Noisy

• Overheating

• Poorly secured

• Running continuously

• Rust

• Too small

• Unbalanced or vibration

Duct & Register Defects on Forced Air Heating Systems

• Balancing damper adjustment

• Dirty, obstructed collapsed

• Disconnected or breached JDG or damaged ducts

• Excessively long runs, excessive elbows

• Wire or pipes in ducts

• Registers or grilles (for return air) in garage

• Rusting or dirty

• In-slab ducts

• Mechanical damage

• Leaky joints

• Insulation missing, damaged

• Filter problems

• Undersized

• Weak airflow

Fan Limit Switch Defects on Forced Air Heating Systems

• Improperly wired

• Missing cover

• Scorching

• Set wrong or defective

• Fan problems

Combination (water to air) Heating System Defects

• Cabinet problems

• Control problems

• Domestic water too hot

• Inadequate heat for house

• Inoperative, inefficient pumps

• Inoperative water heater

• Leaking, clogged coils

• Water control problems

Readers should see FURNACES, HEATING and HEATING SYSTEMS for our complete list of articles on this topic. Also see HOME & BUILDING INSPECTORS & INSPECTION METHODS.

Use the Search Box at the top or bottom of these pages to find in-depth information about building, energy savings, and indoor environment inspection, diagnosis and repair at this website.

Watch out: these inspection lists do not list all possible defects for the systems discussed, and not all home or building inspectors will examine all of the items listed here. CONTACT us to suggest corrections or additions to articles at this website.

See HEATING SYSTEM INSPECT DIAGNOSE REPAIR. Also see HEAT EXCHANGER LEAK TEST, see CARBON MONOXIDE - CO and see GAS PIPING, VALVES, CONTROLS, FLAME COLOR, BLUE vs YELLOW COMBUSTION, FIREPLACES & HEARTHS

These curriculae and building defect lists are based on smilar curriculum documents first prepared by Joe Scaduto, an ASHI member who prepared course material for Northeastern University's Building Inspection Certificate program in 1988, subsequently by DF, InspectApedia's editor, for New York University ca 1988 and later, with others, recommended to ASHI, the American Society of Home Inspectors. ASHI did not adopt this material though currently that association as well as others offer extensive HOME INSPECTOR EDUCATION material. The curriculum and lists of defects are informed by additional analysis of the process of home inspection that was developed beginning Calgary, AB for Canadian and U.S. home inspector education and certification examinations in 1997. Other early contributors to home inspection education in the U.S. and Canada include Dr. Jess Aronstein, Alan Carson, Mike Casey, Mark Cramer, John Cox, Dwight Barnett, Douglas Hansen, Rick Heyl, Larry Hoytt, Bill Merrill, Kevin O'Malley, Dennis Robitalille, Keith Peddie, Pat Porzio, Roger Robinson.

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: johncranor@verizon.net
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides:
- Commercial Building Inspection Courses - protocol ASTM Standard E 2018-08 for Property Condition Assessments
- Home Inspection Education Courses including home study & live classes at eleven colleges & universities.
- Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program.
  Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference Book, a reference & inspection report product for building owners & inspectors.
  Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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- The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.
  Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
- The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones.
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com 11/06
Roger Hankey is principal of Hankey and Brown home inspectors, Eden Prairie, MN. Mr. Hankey is a past chairman of the ASHI Standards Committee. Mr. Hankey has served in other ASHI professional and leadership roles. Contact Roger Hankey at: 952 829-0044 - rhankey@hankeyandbrown.com. Mr. Hankey is a frequent contributor to InspectAPedia.com.
Arlene Puentes, an ASHI member and a licensed home inspector in Kingston, NY, and has served on ASHI national committees as well as HVASHI Chapter President. Ms. Puentes can be contacted at ap@octoberhome.com
Wikipedia provided background information about some topics discussed at this website provided this citation is also found in the same article along with a " retrieved on" date. NOTE: because Wikipedia entries are fluid and can be amended in real time, we cite the retrieval date of Wikipedia citations and we do not assert that the information found there is necessarily authoritative.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

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ASHI Certification Links
Home Inspection Reports - a Critique narrative vs. checklist type home inspection reports
ASHI Standards of Practice - Jan 2000 and ASHI Standards History - links to older and alternative versions of Home Inspection Standards
ASHI Code of Ethics 1993, and ASHI Ethics History - links to older versions; Note: newer may be found at ASHI
ASHI in 1996 ASHI History - association description from 1996
American Society of Home Inspectors (ASHI) Official Website
Basement Moisture Control, U.S. Department of Energy
Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF] ISBN-10: 0471331724 ISBN-13: 978-0471331728
Building Pathology: Principles and Practice, David Watt, Wiley-Blackwell; 2 edition (March 7, 2008) ISBN-10: 1405161035 ISBN-13: 978-1405161039

Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd

Crawl Space Moisture Control, U.S. Department of Energy
Historic Preservation Technology: A Primer, Robert A. Young, Wiley (March 21, 2008) ISBN-10: 0471788368 ISBN-13: 978-0471788362
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Home Inspection Education Curriculum - Heating, Gas Furnaces

4. HEATING, Gas Fired Furnaces Inspection Recommendations & Typical Defects Lists

4.1 Gas Fired Warm (or Forced air? Here “warm air” is a gravity furnace) Air Furnaces

4.1.1 Knowledge Base for inspecting gas fired heating furnaces

4.1.2 Inspection Skills for Gas Fired Heating Furnaces - Warm Air Heat

List of Typical Gas Fired Heating Furnace Defects

Combustion Air Hazards

Gas Burners & Venting, Typical Defects at Gas Fired Heating Furnaces

Evidence of dangerous conditions

Gas Furnace Venting Defects & Hazards

Gas Piping Defects

Mid & High Efficiency Gas Furnace Defects

Combustion Air Defects at Gas Fired Heaters

Warm Air (Forced Air) Heating Furnaces, Gas Fired: Defects

Heat Exchanger Defects

Mechanical Air Filter Defects

Electronic Air Cleaner / Filter Defects

Air Handler Cabinet Defects

Thermostat Defects for Forced Air Gas Fired Heating Systems

Humidifier Defects on Forced Air Gas Fired Heating Systems

Blower Assembly Defects on Forced Air Gas Fired Heating Systems

Duct & Register Defects on Forced Air Heating Systems

Fan Limit Switch Defects on Forced Air Heating Systems

Combination (water to air) Heating System Defects

Frequently Asked Questions (FAQs) about inspection course curriculum and checklist data for forced air gas fired heating systems

Ask a Question or Search InspectApedia

Technical Reviewers & References

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair