Home Inspector Forced-Air Furnace Inspection Flashcards
7 cards from real Home Inspector Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Home Inspector Forced-Air Furnace Inspection flashcards as text
When inspecting a furnace, the inspector finds no sediment trap (drip leg) on the gas supply line. What is the significance?
Answer: Without a sediment trap, debris and moisture can enter gas valve components, causing malfunction
A sediment trap (drip leg) catches debris and moisture before they can reach the gas valve or burner orifices; it is required by most codes on all gas appliance connections.
What is the correct interpretation when a furnace's control board displays a fault code with two LED flashes followed by a pause?
Answer: A specific diagnostic code indicating a fault condition — the meaning must be looked up on the furnace's fault code chart
Modern furnace control boards use LED flash codes to communicate specific fault conditions; the home inspector should reference the fault code chart typically printed inside the furnace panel.
A homeowner reports the furnace produces a loud bang or boom when it starts. What is the most likely cause?
Answer: Delayed ignition causing gas to accumulate before igniting
Delayed ignition allows unburned gas to build up in the combustion chamber; when ignition finally occurs, the accumulated gas ignites with a bang — a condition that can damage the heat exchanger.
What is the minimum vent clearance required between a Category I furnace vent termination and an operable window or door?
Answer: 4 feet horizontally or 1 foot above
Most codes require the vent termination to be at least 4 feet horizontally from or 1 foot above any door, window, or gravity air inlet to prevent combustion gases from re-entering the home.
A home inspector discovers the furnace filter slot has a bypass — air can flow around the filter entirely. What should be reported?
Answer: Unfiltered air bypassing the filter can cause heat exchanger fouling and reduced equipment life — the bypass should be sealed
Air bypass around the filter sends unfiltered dust and debris through the blower and across the heat exchanger, accelerating wear and reducing efficiency.
What does a home inspector look for at the furnace's return air plenum connection to identify a potential indoor air quality hazard?
Answer: Gaps or unsealed connections that could draw in air from unconditioned spaces like crawl spaces or garages
Unsealed return air plenums can draw in mold spores, radon, pesticides, or carbon monoxide from crawl spaces, attics, or garages and distribute them throughout the home.
Which of the following best describes how a home inspector documents a furnace that is functional but has a minor safety concern such as a missing blower door panel?
Answer: Note it as a safety hazard requiring correction, with a recommendation to consult a licensed HVAC technician
A missing blower door affects combustion air balance and safety; it should be documented as a safety deficiency requiring correction by a qualified technician.