LARGER VIEW of an octopus furnaceInspecting Heating Systems, Final Checks

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Heating system inspection procedure: final details. This document presents the final inspection steps and operating suggestions when inspecting residential heating systems . The heating system inspection methodology involved is intended to be generalized to the forensic diagnostic inspection of any complex system in order to have the highest probability of detecting important safety or operating defects. This sounds fancier than intended. Our object is to use an organized procedure for inspecting for defects, without losing the ability to discover unexpected problems as well. The methodology discussed includes both details specific to heating boilers (the full outline at "Contents") and more general complex-system inspection methods (listed immediately below).

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© Copyright Daniel Friedman 2008-1993 all rights reserved -- Tri-State ASHI Seminar -- Last update 08/03/2010 - first presentation November 6-7, 1993

Final heating system inspection checks in the boiler room:

Operate the Heating Equipment

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 - see BOILER OPERATING PROBLEMS

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.
  • Startup problems: noises, puff back, flapping barometric damper, vibrations
  • 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

What are the Implications of the Clues of Heating System Defects that You Observed?

  • Leaks 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?

Remember that even a subtle clue like drips at the bottom of a relief valve discharge tube can have profound implications for the condition of the heating system. Clues make more sense when you understand how the equipment works, its operating cycle, and the function of each component.

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.

Thought Sequences for Final Heating System Check

  • 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?

Heating Inspections: Safety Concerns for the Home Inspector

This section contains examples of steps to protect the inspector. It does not address safety concerns for the client/occupant.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)
  • 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 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
  • Watch for flashback at inspection ports
  • Watch for electric shock at controls
  • Do not pick at corrosion
  • Do not test relief valve levers nor catch your sleeve on one
    ASHI 9.3.B. The inspector is not required to operate automatic safety controls
  • Do not light fires in coal or wood stoves to check draft, etc
    ASHI 9.3.C. The inspector is not required to ignite or extinguish solid fuel fires
  • Do not disassemble flue vent piping - risks of filth, unable to reassemble, etc.
    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]
    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.]
  • 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 exchanger.
  • Avoid electric shock from the static charge at electronic air filters.
    ASHI 9.3.D.4 The inspector is not required to observe electronic air filters


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