Safety tips for inspecting & repairing central heating systems
Home inspection class: heating system inspection
Course on home inspection safety during heating system examination and testing
Questions & answers about safety hazards on and around residential heating equipment
Here we explain safety procedures and tips that are important during heating system inspections.
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This website answers most questions about central heating system troubleshooting, inspection, diagnosis, and repairs.
We describe how to inspect
residential heating systems to inform home owners, buyers, and home inspectors of common heating system defects. The articles at this website describe the basic components of a home heating system,
how to find the rated heating capacity of an heating system by examining various data tags and components, how to recognize common heating system operating or safety defects, and how to save money on home heating costs.
We continue to add to and update this text as new details are provided. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
This section describes examples of steps to protect the home or heating system inspector during the inspection of a heating system.
It does not address safety concerns for the client/occupant or unsafe conditions on the heating equipment itself, though those
are addressed in other articles at this website. ASHI 9.3.A. The inspector is not required to operate equipment
when weather conditions or other circumstances may cause equipment damage [or in the opinion of the inspector, may cause any sort
of unsafe condition (added by DJF, NOT ASHI Standards)
In order to be as thorough, accurate, and safe as possible, a heating system inspector should use a well-defined order of discovery
which assures that s/he examines all important heating system components. Several possible heating system inspection "road maps" can be used
for this purpose and are described at this website.
Air Filter Shock Hazards: Avoid electric shock from the static charge at electronic air filters. - Home inspection standard example: ASHI 9.3.D.4 The inspector is not required to observe electronic air filter
Backpressure or Flashback: Watch for flashback or backpressure at inspection ports on heating equipment
Blocked heating flues: a blocked flue can cause the production of potentially fatal carbon monoxide gases in a building. A blocked flue case study is reported at UNLINED FLUE INSPECTIONS.
BLUE vs YELLOW COMBUSTION FLAMES - the Blueray history and blue flame vs. yellow flame combustion, flame color & combustion efficiency, & how oil competes with gas as a heating fuel.
CHINESE DRYWALL HAZARDS - corrosion risks to HVAC condensing and cooling or heating coils, possible corrosion risks to HVAC metal ductwork from corrosive gases produced by Chinese drywall.
Confirm Heat Operation Before Leaving: To avoid a future dispute about having been the cause of lost heat in a building, particularly in cold weather, if the system was on and running, observe and note that it was running normally at the end of the inspection procedure. This is important if your inspection procedure includes any action that may temporarily shut off the system such as testing a shutoff switch.
Corrosion on Heating Systems Do not pick at corrosion on heating systems - you may cause a catastrophic leak that requires immediate system shut-down - which in freezing weather risks freeze-damage to the building.
Disassembling flue vent connections: Do not disassemble flue vent piping - risks of filth, unable to reassemble, etc. Home inspection standard example: ASHI 9.3.D.1 The inspector is not required to observe the interior of flues [However often you can detect a blocked flue by looking through the barometric damper or by use of a mirror at the chimney cleanout. We recommend this step. -DJF] Home inspection standard example: ASHI 9.3.D.2 The inspector is not required to observe fireplace insert flue connections [Normally not visible. Caution: there is frequently a hidden problem there.]
DUCT SYSTEMS - air leaks, unsafe ductwork, inadequate supply or return air, other defects
Odors From Heating Systems - a list of articles addressing the sources of odors produced by various types of heating systems - how to find, diagnose, and correct these possibly dangerous conditions.
When to Shut Down Heating Systems: Turn off heating equipment immediately if you see conditions that appear to be unsafe, such as evidence of fire, smoke, puffback, or if you see safety controls such as relief valves, temperature limits, or flue gas spillage sensors which have been removed or modified, or if the equipment has already been "red-tagged" by a service technician.
When to Avoid Turning On Heating Systems: Do not turn on heating equipment if you see any condition that appears to be unsafe. Some examples are listed here.
Do not turn on equipment which has been "shut down" - Possible open piping, unsafe wiring, leaks, unsafe chimney, fire risks.
Do not turn on equipment which has been switched off without explicit permission/instruction from a responsible party
Examine gauges (not entirely reliable) for unusual pressure or temperature conditions and do not permit such equipment to continue to operate
Do not turn on, or turn off if already operating, any heating system whose temperature/pressure gauge shows abnormally high operating values
Do not operate equipment which does not appear to be vented properly; shut down equipment if, on operating it, you observe an apparently blocked flue
Do not operate equipment if the chimney is suspect--e.g. old single wythe unlined brick with visible damage in the attic or outside
Do not turn on, or turn off if already operating, any heating system that is not safely connected to a chimney
Humidifier Inspections: Be careful about disconnecting humidifiers to obtain access to furnace plenums: you may cut yourself on sheet metal, cause leaks in humidifier piping, cause spills. ASHI 9.3.D.3 The inspector is not required to observe humidifiers
But watch for humidifiers which leaked into and damaged duct work or onto and damaged a heat exchangers
Lighting test fires: Do not light fires in coal or wood stoves to check draft, etc Home inspection standard example: ASHI 9.3.C. The inspector is not required to ignite or extinguish solid fuel fires
Noises, smoke, soot, back pressure at inspection port (watch out for burns and fires if this port is opened), sloppy startup, rumbling, sloppy or delayed shutdown-flame lingers COULD indicate a very dangerous operating condition.
Relief Valve Testing on Heating Systems: Do not test relief valve levers nor catch your sleeve on one Home inspection standard example: ASHI 9.3.B. The inspector is not required to operate automatic safety controls
Shock Hazards at Heating Controls: Watch for electric shock at controls
Questions & Answers regarding this article
Questions & answers about safety hazards on and around residential heating equipment
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Additional technical contributors & reference sources for this article are listed below.
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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, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book 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. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
Domestic and Commercial Oil Burners, Charles H. Burkhardt, McGraw Hill Book Company, New York 3rd Ed 1969.
National Fuel Gas Code (Z223.1) $16.00 and National Fuel Gas Code Handbook (Z223.2) $47.00 American Gas Association (A.G.A.), 1515 Wilson Boulevard, Arlington, VA 22209 also available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269. Fundamentals of Gas Appliance Venting and Ventilation, 1985, American Gas Association Laboratories, Engineering Services Department. American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209. Catalog #XHO585. Reprinted 1989.
The Steam Book, 1984, Training and Education Department, Fluid Handling Division, ITT [probably out of print, possibly available from several home inspection supply companies] Fuel Oil and Oil Heat Magazine, October 1990, offers an update,
Principles of Steam Heating, $13.25 includes postage. Fuel oil & Oil Heat Magazine, 389 Passaic Ave., Fairfield, NJ 07004.
The Lost Art of Steam Heating, Dan Holohan, 516-579-3046 FAX
Principles of Steam Heating, Dan Holohan, technical editor of Fuel Oil and Oil Heat magazine, 389 Passaic Ave., Fairfield, NJ 07004 ($12.+1.25 postage/handling).
"Residential Hydronic (circulating hot water) Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
"Warm Air Heating Systems". Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
Heating, Ventilating, and Air Conditioning Volume I, Heating Fundamentals,
Boilers, Boiler Conversions, James E. Brumbaugh, ISBN 0-672-23389-4 (v. 1) Volume II, Oil, Gas, and Coal Burners, Controls, Ducts, Piping, Valves, James E. Brumbaugh, ISBN 0-672-23390-7 (v. 2) Volume III, Radiant Heating, Water Heaters, Ventilation, Air Conditioning, Heat Pumps, Air Cleaners, James E. Brumbaugh, ISBN 0-672-23383-5 (v. 3) or ISBN 0-672-23380-0 (set) Special Sales Director, Macmillan Publishing Co., 866 Third Ave., New York, NY 10022. Macmillan Publishing Co., NY
Installation Guide for Residential Hydronic Heating Systems
Installation Guide #200, The Hydronics Institute, 35 Russo Place, Berkeley Heights, NJ 07922
The ABC's of Retention Head Oil Burners, National Association of Oil Heat Service Managers, TM 115, National Old Timers' Association of the Energy Industry, PO Box 168, Mineola, NY 11501. (Excellent tips on spotting problems on oil-fired heating equipment. Booklet.)
Links to our list of additional information on heating system inspection, repair, maintenance
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