Sooty gas burner (C) Daniel Friedman Warm Air Furnace Heat Inspection Steps
Additional Inspection Steps for Heating Systems & Heating System Controls

  • HEATING FURNACE INSPECTION GUIDE - CONTENTS: Procedures for inspecting warm air heating furnaces - alternative approach focuses on furnace or boliler controls. How to inspect a warm air heating furnace system - operating sequence summary, controls, switches, inspection points. How to check the controls on heating systems - special controls & devices
  • POST a QUESTION or READ FAQs about heating system inspections

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How to inspect warm air furnace heating systems & additional heating system inspection points - heating controls.

This document presents alternative sequences & methods 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.

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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Furnaces - Hot Air Heating System Inspection & Sequence of Operation

Furnace sketch (C) Carson Dunlop AssociatesWorking Definition of a Heating Furnace

A warm air heating furnace (some call it hot air heat) 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

Sketch at left courtesy of Carson Dunlop Associates.

An Outline of Inspecting a Warm Air Heating Furnace System by Understanding its Sequence of Operation

Details of how a furnace works are at FURNACE OPERATION DETAILS.

Here we summarize that process and name some inspection topics and concerns. If the furnace is already known to be not working at all or not working properly, start at DIAGNOSE & FIX FURNACE.

Furnaces have a simpler, operating sequence than heating boilers that were discussed in earlier articles of this series

Sooty gas burner (C) Daniel Friedman

Watch out for sooty gas burners: If you see soot on or around gas burners such as shown in our photo (above) you should shut off the equipment (it is unsafe) and call a heating service technician promptly.

If this is the problem, cleaning rust and debris off of the pilot and igniter, or rust and debris off of the burners and checking their adjustment might fix the trouble. If the gas burner tubes include flame crossover slots, those are intended to assist the spread of flame from the first ignited gas burner tube over to the other tubes. Be sure those slots are cleaned as well.

How to Understand the Implications of Inspection Observations when Inspecting Warm Air Heating Systems

Understanding the heating furnace functions and sequence operation leads to an understanding of the implications of what might be observed during a heating system inspection, including important factors outside of the heating equipment itself.

Examples of important heating system site observations where a furnace is installed

Alternative Heating System Operating & Inspection Sequences - check the controls

Eg: immediate burner on when the thermostat is turned-on from the living area.

How to recognize different types of heating systems & controls - these are not found on forced air furnaces

Example of understanding function=understanding implications

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?

© Copyright Daniel Friedman 2014-2015 all rights reserved -- Tri-State ASHI Seminar -- Last update 08/03/2014 - first presentation November 6-7, 1993


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



Or see NO HEAT - FURNACE if the cussed furnace is not working at all (what did you break?)


Or see these

Heating System Inspection Procedure Articles

Special inspection points for heating furnaces

Suggested citation for this web page

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


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