For licensed inspectors
Inspecting a furnace: gas, electric, and other heat
To tell if a furnace is gas, look for a gas meter or propane tank, a dedicated gas pipe and shutoff at the appliance, a vent or flue, and a burner compartment—electric furnaces have heavy electrical supply and no combustion vent, and heat pumps move heat with outdoor equipment instead of burning fuel.
How home inspectors identify gas vs electric heat, what to look at on a furnace, and how to report heating without performing an HVAC design review.
Identify the fuel before you operate
Gas (natural gas or propane): black iron, CSST, or copper (where allowed) to a shutoff, a gas meter or tank, a draft hood or inducer and a flue or PVC vent on high-efficiency units, and a burner tray behind an access panel. You should smell no gas. If you do, stop, ventilate if trained to, and do not operate.
Electric furnace or air handler with electric heat: large-gauge conductors or a heat kit, no fuel pipe, no combustion flue. Heat pump: outdoor condensing unit, refrigerant lines, and often electric backup strips in the air handler. Oil: tank, filter, barometric damper, and soot-prone flue. Dual fuel mixes a heat pump with a gas furnace.
What a general inspection includes
Name the equipment (forced air, boiler, wall furnace, mini-split), approximate age from the data plate, filter access, rust or water at the secondary heat exchanger or condensate on high-efficiency gas, and a representative heat operate when weather and safety allow. Listen for unusual noise; look at the flame if you can do so without defeating safeties (steady blue on many gas burners; yellow lifting flame is a note, not a lab analysis).
You are not measuring combustion efficiency, pulling the heat exchanger, or verifying Manual J. Recommend an HVAC technician for cracks, soot, cycling, CO concerns, or a unit that will not fire.
Distribution and safety
Follow a few ducts or pipes: disconnected flex, crushed return, missing insulation in unconditioned space. Note combustible clearance, dedicated receptacle vs. extension cord, condensate drain on 90%+ furnaces, and whether there is a carbon monoxide alarm where required. Boilers: leaks, expansion tank, pressure, and mixing with domestic water if you see a sidearm.
Reporting fuel type clearly
Clients mix up “gas in the house” with “gas heat.” Write the heating fuel in the HVAC section: “Forced-air furnace, natural gas, vented through PVC (condensing).” If the cooktop is gas but heat is a heat pump, say both. Photograph the data plate and the gas shutoff; that photo answers most “is it gas?” follow-ups.
Common questions
- The listing said gas but I see a heat pump. What do I write?
- Write what is installed. Listings are often wrong. Note the outdoor unit and the air handler; mention backup heat if you identify strips or a furnace.
- Can I light a pilot?
- Only if it is within your SOP, you are competent, and the equipment looks safe. Many inspectors will not light a standing pilot that is off. Report it as not operated and why.
The listing said gas but I see a heat pump. What do I write?
Write what is installed. Listings are often wrong. Note the outdoor unit and the air handler; mention backup heat if you identify strips or a furnace.
Can I light a pilot?
Only if it is within your SOP, you are competent, and the equipment looks safe. Many inspectors will not light a standing pilot that is off. Report it as not operated and why.