Heating boiler inspection procedures & checklists:

This document presents the detailed sequence of steps to use when inspecting residential heating systems with focus on heating boilers and furnaces, on assuring completeness, accuracy, and on maximum heating system defect detection.

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).

© Copyright Daniel Friedman 2024-1993 all rights reserved -- Tri-State ASHI Seminar -- Last update 02/03/2024 - first presentation November 6-7, 1993

Detailed Steps in the Sequence of Examination of Oil-Fired Hot Water Boilers

Viewpoint #4--Detailed close scrutiny of the equipment, after a few "sanity checks"
ASHI 9.1.A.1 The inspector shall observe ... heating equipment

Article Contents

• HEATING BOILER INSPECTION GUIDE
  • HEATING SYSTEM INSPECTION SEQUENCE
  • HEATING BOILER CLEARANCE DISTANCES - steam & hot water boiler working space & fire clearances
  • INSPECT HEATING CONTROLS
  • INSPECT FOR HEATING BOILER LEAKS
  • HEATING SYSTEM DEFECT SIGNIFICANCE

Inspect before operating the boiler

What are we looking at? Form a working Definition: 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 No. 2 home heating oil (or gas in a gas fired heating boiler) 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.

We include links to detailed heating system articles that explain how boiler or furnace parts and components work, how to inspect or repair them, and description of common problems that occur with each heating system component.

• Do you see some reason not to turn this system on? (See SAFETY, HEATING INSPECTION.) 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.

Examine components in the sequence of operation

Training in proper operation sequence of the 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.

The steps in a heating boiler operating sequence are discussed in detail

at BOILER OPERATING STEPS - the 39 steps in a hot water boiler operation when fueled by gas or oil.

Similar information is provided for warm air heating systems

at FURNACE OPERATION DETAILS.

Look closely at controls, peripherals, key components,

while going through the detailed sequence
ASHI 9.1.A.3 automatic safety controls

• Combination control - combining High Limit and "Low Limit" (which may or may not be in use depending on presence of a tankless coil).
  
  See BOILER CONTROLS & SWITCHES for details.
• High Limit and Low Limit (if tankless coil) separate controls on older equipment
  
  - Limit Switches, Boilers
• Flame sensing device: Cad Cell or Stack Relay (watch for sensitive relays and learn about the re-stepping lever)
  
  - CAD CELL RELAY SWITCH
• Automatic water feeder and Expansion Tank
  
  - EXPANSION TANKS
• Pressure Relief Valve
  
  - RELIEF VALVES - TP VALVES
• Pressure and Temperature gauge--12 psi cold, less than 30 psi hot. Over 30 psi dumps relief valve.(Typical operating temperature settings LO-120-160 HI-180-200 °F. Typical operating temperature observed at the gauge will be below the high, and can be as low as nighttime room temperature in non-heating season if no tankless coil is in use. The temperature/pressure gauge may help in checking for normal conditions before and during boiler operation. However the gauge can be wrong!)
  
  - Gauges on Heating Equipment
• Tankless coil--leaks, missing mixing/tempering valve, relief valve (some jurisdictions). Risk of scalding water at the house sinks/tubs if there is no mixing valve.
  
  - TANKLESS COILS

Leaks and Corrosion - some implications

• Surface rust--repairable. Clean when serviced and monitor
• Exfoliation--very serious, possibly not repairable, risks loss of boiler.

Common Heating System Leak Locations

• Coil mounting plate - see rust stains below and around plate
• Pipe fittings at face of coil plate - mineral salts
• Leaks around bolt openings - suspect hidden damage

Examples of understanding function and implications:

• Leaks are never acceptable, anywhere on a heating system. Leaking relief valves need immediate attention and repair (Leaking relief valve could be due to water-logged expansion tank, improper control settings (temp 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
  
  Do not touch the relief valve- it may open and fail to shut down.
  
  Do not pick at corrosion as you may start a catastrophic, un-stoppable leak requiring total system shut-down.
• Different water pressure/flow observed in the kitchen: hot water pressure significantly less than cold--is a tankless coil installed? is a water softener installed? is there "hard" water--have mineral deposits clogged the coil? Are there "cleanout" plumbing fittings on the 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 coil mounting plate?
  

...

Continue reading at FINAL BOILER/FURNACE ROOM INSPECTION CHECKS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• BOILER OPERATING PROBLEMS for details of heating boiler troubleshooting or trouble signs
• BOILER CLEARANCE DISTANCES
• CLEARANCE DISTANCES for BUILDING SYSTEMS & FEATURES - topic home
• HEATING SYSTEM INSPECTION - home
• HEATING SYSTEMS - home
• HEATING INSPECTION CONCEPTS
• HEATING INSPECTION PROCEDURE-GENERAL
• HEATING SYSTEM INSPECTION DETAILS
• INDOOR INSPECTION of HEATING SYSTEM
• HEATING BOILER INSPECTION GUIDE
• HEATING FURNACE INSPECTION GUIDE
• FINAL BOILER/FURNACE ROOM INSPECTION CHECKS
• GAS BURNER FLAME & NOISE DEFECTS
• GAS BURNER SOOT CAUSE & CURE
• GAS BURNER PILOT LIGHT PROCEDURE
• OIL BURNER INSPECTION & REPAIR
• HEATING SYSTEM SAFETY INSPECTION
• SAFETY RECALLS CHIMNEYS VENTS HEATERS

 

Suggested citation for this web page

HEATING BOILER INSPECTION GUIDE at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING SYSTEMS

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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