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This article series gives detailed step by step procedures to be used during the inspection of a heating system in order to be thorough, organized, and accurate. We describe how to inspect, troubleshoot and repair heating and air conditioning 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.
How to Inspect Heating Systems - Example of An Approach to the Forensic Inspection of Any Complex System
This document presents a detailed methodology for inspecting, diagnosing, & repairing defects on residential heating systems
with attention to inspection methods selected to assure completeness, accuracy, and the maximum level of defect detection.
The heating system inspection methodology described here serves as a guide to the forensic diagnostic inspection of any complex system where the highest probability of detecting
important safety or operating defects is important.
We describe organized procedures for inspecting complex systems for defects, without losing the ability to discover unexpected problems as well.
How to Relate Heating System Inspection Procedures to Home Inspection Standards of Practice
This presentation follows a procedure for inspecting, using heating system operating sequence as a method to assure that all important
system components are considered. A version of the ASHI Standards of Home Inspection Practice (readers should check most
recent Standards version for changes) is mapped into this heating system inspection procedure but does
not guide the actual inspection sequence. The organization of home inspection standards is not intended as a guide to an
inspection sequence nor as a guide to heating system inspection reports.
Home Inspection Standards requirements during the inspection of a home heating system are identified in italics in the text below.
HEATING INSPECTION PROCEDURE - A Detailed Step by Step Inspection Procedure for Heating Systems & Heating Equipment
Heating System Inspection: Outdoor Observations
Outdoor heating system inspection from a distance
Viewpoint #1:--Distant (from the heating equipment): walking
around the house, from the ground, just looking, notice and record:
Type of Heating Equipment Installed
Age of the neighborhood, other inspections done in the area, age of
the house, may suggest type and even the brand of equipment which
may be in place. Builders of developments often purchased many of
the same brand and model for all the houses there.
What Heating Fuel Is or Has Been in Use
ASHI 9.2.A.1 The inspector shall describe the energy source
Identify probable fuel source: oil, gas, electric, coal, wood, solar
Notice the oil filler and vent, spills, and whether or not there is easy access to
the oil tank filler pipe.
Also notice any evidence of old, possibly abandoned oil tanks (abandoned oil lines, protruding pipes, age of property, depressions in the soil), or
of changes from one type of fuel to another (coal bins). These have potentially major cost implications (improperly abandoned oil tanks)
or safety concerns (changes of fuel, unsafe chimneys).
Venting and possible hazards noted from outside:
[Examples of "distant" implications]
ASHI 9.1.A.4 chimneys, flues, and vents
Look for, then at the chimney. Is there a chimney?
If not is there electric heat, direct-vent equipment, or no heat?
Thinking about what chimneys do lets you understand the implications
of your observations. These items are examples, not a comprehensive
Heating System Chimney & Venting Observations Made From Outdoors
Here are examples of outdoor observations that should be noted: they provide important information about the type, condition, and safety of the heating system in a building.
Sooty chimney top or soot stains on roof: system has not been operating properly
Soot washed off: system may have been repaired/replaced
Soot heavy and fresh or smoky exhaust seen, system currently needs service or repair
Watch out for Repco™ boilers which run sooty as they crash.
[Do not confuse Repco™ heating boilers, which had fire chamber and other failures, with other products (REPCO pumps, REPCO controls, REPCO water conditioners, or water treatment that carry the Repco name. Those products are distinct from REPCO heating boilers and are produced/distributed by the R.E. Prescott Company. Further, we are unaware of any remaining warranty or replacement support for failed or antiquated Repco heating boilers.]
Heat seen rising from heating flue in July - the house may have a tankless coil for domestic hot water. If not, is the primary control set up properly?
Is there a separate oil-fired water heater using same flue? What's running making that exhaust? Reserve questions for later.
If there is no chimney cap
is flue blocked by debris?
has wind-blown rain damaged the masonry interior?
has wind-blown rain run down chimney into flue vent piping and on into the equipment?
Did it cause rust damage? Fire chamber damage?
damaged flue liner? Damage by condensation, frost, acid rain, sulphation (especially with gas-burning equipment)
Unlined single-wythe brick flues (still common in large cities)--if damaged, risk of fire, leaking flue gases, blocked flues. Look further in the attic and assure there's a cleanout or suggest vent connector be pulled to check for blockage.
Old stone chimneys
often stop at foundation, heaters were added, connected in to very base of chimney - easily blocked by fallen debris.
Signs of history of water entry (risk unsafe flue: blocked, fire risks - falling debris
possible damaged heating equipment (more likely for furnaces than boilers)
Heating System Chimney & Oil or Gas Supply Observations Made From Outdoors
buried tanks or underground oil storage tanks
indoor tanks used outside
risks of water entering fuel from location of filler
evidence of fuel spills such as stains, dead or damaged grass or shrubs
evidence of fuel leaks such as wet oil piping, stains at gas fittings, gas odors
ease of access to oil filler pipe or gas meter
oil filler pipe left in place when the house converted to gas? (Potential very serious problem if oil is delivered by mistake.)
Gas meter not protected from vehicles, in ground contact, damaged, or with inaccessible shutoff
Heating System Inspection: Indoor Observations
Viewpoint #2--Distant view of the heating equipment from the living area.
Heating System Inspection In the living area
These observations and conclusions can be made quickly without needing
to ask anyone anything, as soon as you enter the building:
Type of Heat Distribution ASHI 9.1.A.7 the presence of an installed heat source in each room.ASHI 9.3.D.4 The inspector is not required to observe the uniformity of heat supply to various rooms.
Air registers: hot-air furnace. Begin looking for supply and return grilles. Identification tip: return grilles often have no controlling louvers and may be centrally located. Distribution problems are not discussed in this presentation.
Baseboards - electric or hot water. Leak stains, repairs indicating history of freeze-ups?
Radiators - hot water or steam. Steam: observe steam valves on each radiator and identify one pipe vs two-pipe distribution system.
Nothing visible: is there electric or hot water radiant heat. Watch for multiple types of heat supply: e.g.: baseboards, with electric heaters in bathrooms.
Heating System Observations In the Utility Room
Viewpoint #3--Distant broad view of the heating equipment from the utility room.
The equipment is directly in view but not yet closely examined. ASHI 9.1.A. The Inspector shall observe permanently installed heating systems including: [items are listed later] ASHI 9.2.A.2 The inspector shall describe heating equipment and distribution type
Identify/confirm type of equipment
Housekeeping, location of combustibles
Sooty operation, odors, noises
Evidence of recent maintenance
Service tags vs filth atop the equipment or in the chimney was it really serviced?
Heating Boilers Detailed Inspection Guide
Viewpoint #4--Detailed close scrutiny of the equipment, after a few "sanity checks" ASHI 9.1.A.1 The inspector shall observe ... heating equipment
Heating Boiler Inspection Before Operation
What are we looking at? Form a working definition that helps clients understand the system too: A system
which heats the house. A steel, copper, or cast iron "box" of hot water, connected to a loop of pipe (and radiators or baseboards)
which runs around through the living area. The same physical water stays in the boiler and is circulated by a pump so that heat is delivered
to the living area. Burning oil makes hot gases which are used to heat the water before being exhausted outside. Pumps move fluids.
Safety controls at various points protect against a number of potential hazards.
Do you see some reason not to turn this system on? (See Safety Concerns for the Home Inspector below.) What about other problems?
Is the system safely connected to a chimney?
Look at the temperature/pressure gauge: normal operating values?
Look for leaks in the boiler itself (Cast iron is more resistant to death by leaks than steel. Older cast iron systems without tankless coils, if shut off in summer, may be at risk of leakage and hidden damage. Steel rusts through. Cast iron cracks or leaks at joints.)
Look for leaks at controls now and again in the sequence below
Leaks at valves or fittings which drip into the jacket of a steel boiler or onto controls or zone valves risk failure and loss of heat.
Is there a tankless coil? If so, address both topics, looking at heating first, DHW second.
Heating Boiler Inspection by Sequence of Operation
Training in proper operation sequence of heating system equipment and in the
function of its controls is a step towards technical correctness.If you do not understand how a mechanical system works you cannot
reliably expect to observe missing or defective components. This discussion is an exercise using sequence of operation to work
for completeness. It is not technically exhaustive, it focuses on a specific example: oil-fired hot water, zoned, heating system.
Examine the accessible parts of the system. Let your eye travel from component to component in the sequence of operation. Apply the
inspection logic discussed earlier, at each step. Consider the implications
should each component be missing, damaged, inoperative, leaky, noisy, sooty, repaired by an amateur, etc.
Think through the operating sequence as you examine each component in that order.
The following are the steps in one common set-up. This list is lengthy
and detailed. The actual visual examination may take only a few minutes.
How a Heating System Works - 39 Steps in the Operation of a Heating System
For a complete and accurate inspection of a heating system, the inspector may
think through the step by step description of how a heating boiler works. In the reference cited just below we name each heating system
component and what it does, in the order that heating system components operate during the heating cycle.
Items shown in [brackets] are ones which may not be present on some heating systems.
The detailed step by step description of how a heating boiler operates can be read at
BOILER OPERATION DETAILS
How to Inspect the Heating System Controls and Switches
While going through the detailed sequence in the operation of the heating boiler, the heating system inspector
should watch for and inspect the condition of the heating
boiler controls and safety devices (as required by ASHI 9.1.A.3 automatic safety controls).
Our detailed description of heating system controls, what they do, how to set them, how to inspect them, is
at BOILER CONTROLS & SWITCHES
How to Inspect Heating Systems for Leaks, Rust, Corrosion Damage
The inspector must be particularly alert for evidence of leaks, corrosion, or other signs of damage to the
heating system. Our detailed description of where to look for leaks on heating boilers and what those
leaks or leak signs may mean can be found at BOILER LEAKS CORROSION STAINS
How to Recognize Heating System Defects by the Implication of Clues
The heating system inspector must be alert for many signs of heating system malfunction or safety defects. To inspect
a heating system effectively, the inspector must understand the implications of what s/he is observing since otherwise
an important clue may go unrecognized and a major heating system defect may go unreported. We discuss
the interpretation of heating system observations and clues further at
Heating Equipment Malfunction & Implications. For still more details about heating system malfunctions see BOILER OPERATING PROBLEMS for an extensive list of heating system clues and what they mean for the safety, adequacy, or reliability of the heating system.
Heating Boiler Inspection Final Checkpoints
How to Operate Heating Equipment During an Inspection
After all visual inspection. Avoids running dangerous systems, permits
explanation to client without background noise. Permits observations
of operation anomalies.
ASHI 9.2.B. The inspector shall operate the system using normal operating controls such as using the thermostat
Heating System Operating Defects
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 (very dangerous).
Feeling piping (hot!) can indicate if circulator is running--quick change in temperature vs convection.
Some leaks occur only at peak operating temperature--eg at relief valve.
Particularly in cold weather, if the system was on and running, observe and note that it was running normally when you last touched it. Witnessed. (Frost damage issues lurk here.)
Heating Equipment Malfunction & Implications
Leaks on heating equipment and its piping or controls are never acceptable, anywhere. Leaking relief valves need immediate attention and repair (Leaking relief valve could be
due to water-logged expansion tank, improper control settings (temperature too high), improper automatic water feeder operation (pressure too
high), or defective valve (leaky). True, you only have to report the valve. Did you miss problems at the other components?) Corroded relief
valves also need test and repair/replacement
Relief Valves: Do not touch the heating boiler or water heater temperature or pressure relief valve - it may open and fail to shut down.
Corrosion on heating system parts: Do not pick at corrosion as you may start a catastrophic, un-stoppable leak requiring total system shut-down.
Tankless coils for making hot water: If there is different water pressure/flow observed in the kitchen in which the
hot water pressure is significantly less than cold, even before examining the building's mechanical systems you may
speculate that a tankless
coil installed may be installed. What other clues suggest that the local water supply may be hard in
minerals and that there may be a risk of clogged piping? When the water supply is high in minerals, the hot water pipes or tankless coils clog up before cold water piping.
Is a water softener installed? Is there known "hard" water--have mineral deposits clogged the coil? Are there "cleanout"
plumbing fittings on the tankless coil piping? Does this suggest a history of clogging and acid-flush treatments? Can a clogged coil be repaired
or replaced? How severe was that rust you observed at the tankless coil mounting plate?
Heating System Operating Sequence Inspection Tips
If the furnace or boiler turns on immediately when the thermostat is turned-on or up from the living area what does this mean?
Alternative Heating System Controls
Air vents at radiators - may indicate that there has been a history of air blockage in the hot water heating system.
Pressure switch at a steam boiler is typically set to .2 to .5 psi. Higher settings may indicate a history of difficulties with heat distribution in the building.
Lower-pressure relief valve
Water feeder, manual or automatic. (Don't mess with either, they may open and be hard to shut off.)
Low Water Cutoff on some systems. (Also found on some hydronic boilers.)
Different piping on some systems - one-pipe vs two-pipe, easy to identify and very different implications for retrofit/conversion to other heating methods such as hot water.
Immediately recognized from the living area by presence of steam valves on radiators. Don't confuse steam valve with air bleeder valves found on hot water radiators.
Steam rises--hence no circulator pump may be installed - if you see a pump is it a separate hydronic zone? (Some steam systems also circulate hot water through a lower building area. Or is the pump you see a condensate return pump?
Heating System Component Malfunction Example
A pressure control set to 10 PSI indicates some operating problem
with system, addressed by a service person who's trying to "force" steam into the house rather than debugging a problem, probably with
piping or steam valves. Service has been by someone unfamiliar with steam systems.
Absence of any sign that the occupants ever drain and clean the automatic water feeder suggests risk of inoperative key safety device. Needs
attention even if you see absolutely no problems. Modified piping? improperly sloped radiators?
A Guide to Hot Air Heating Furnace Inspections
Furnaces follow a simpler operating sequence than hot water boilers and steam boilers which we discussed above.
Hot air heating furnaces use different controls than hot water boilers since the furnace distributes heat by warm air. For example, a fan/limit switch is normally used to turn the blower on and off.
A Working Definition of a hot air furnace can aid explaining the system to clients and owners: A furnace is a steel or cast iron "box" connected to a series of duct work which runs through the house bringing
hot air to grilles (registers). A fan, usually at the furnace, circulates air from cold-air return grilles through duct work to the furnace
where the air is heated and then returned through "supply ducts" to the living area.
Operating sequence of a hot air heating furnace: The building or building room cools, as temperature drops the thermostat switch closes (calls for heat), oil burner is turned on, oil is pumped from tank to burner, ignited, burned,
Hot gases pass through a fire chamber (steel can) and out an exhaust flue, past a barometric damper to a chimney to outdoors.
ASHI 9.2.C. The inspector shall open readily open-able access panels provided by the manufacturer or installer for routine homeowner maintenance
Understanding functions=understanding implications: eg: wet basement, steel furnace, high CO risks from rusted heat exchanger.
Heating System Inspection Final Check Thought Process
Hot heating water movement from house supply into boiler, through circulating equipment.
Fuel movement from tank through burner up flue and chimney.
Air movement into house and to burner and up flue and chimney.
Air movement inside duct work (for furnaces)
Complete operation sequence reviewed?
Other building conditions observed which raise questions?
wet basement, poor housekeeping, poor maintenance, extensive building additions may stretch boiler capacity, ...
What's missing ?
Did we leave the system operating normally?
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R.E. Prescott Company, a producer of other REPCO™ residential and industrial products as well as a provider of design-build engineering services is at 10 Railroad Avenue, Exeter, NH 03833. Tel: 603-722-04321 or 888-786-7482. Trish O'Keefe from Prescott informed us (10/7/2009) that their company had nothing to do with the failed Repco heating boilers discussed at InspectAPedia.com. She wrote:
Our company manufactures & distributes residential water treatment equipment, including our Repco line of conditioners. We have a plumbing & heating supply dept as well. We are mistaken for the Repco Boiler company on a regular basis, most frequently in Oct. and Nov.
Any information you could give me on the other Repco company would be appreciated. We've assumed it is no longer in business, and we'd like to know that for sure. Many callers want to know where to get replacement parts and I would be glad to direct them if I knew...plus there's always a chance they might be interested in a Crown Boiler instead
Information on Hydronic (hot water) Heating Boilers:
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.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
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