An annual furnace inspection can ensure your heating system works reliably all season. It can also improve energy efficiency, avoid expensive repairs, and add years to your furnace’s life. If you’re wondering what an inspection looks like, this checklist summarizes our HVAC maintenance technicians’ process during a yearly tune-up.
Determine the Furnace Is Safe to Operate
The technician verifies the system is operating properly. They may check for a blinking light that indicates an error code and check it against a table or chart on the furnace. Any issues are documented in a report and the technician will take steps to troubleshoot and resolve them.
Observe the System’s Sequence of Operation
Once the thermostat prompts the unit to produce heat, the inducer motor should turn on and then the ignitor should follow. The inspector will see that the gas valve opens and that fuel is supplied to the burners, which should ignite as normal. They’ll check the flame sensor is working, the exchanger is heated, and the blower fan turns on (and that the desired temperature change (Delta T) is achieved).
Verify the Furnace Is in a Suitable Location
For accessibility, a furnace must be in an unobstructed area with at least 24 inches of floor space. If it’s in an attic or crawlspace, the opening must be at least 30 inches high and 22 inches wide; flooring must be solid, continuous, and at least 24 inches wide. There must also be at least a 20- x 30-inch opening for the furnace and a 30- x 30-inch level workspace in the front. Furnaces cannot be placed in a bathroom, sleeping area, or storage closet.
The technician will note the location of the furnace, its energy source and heating method, and if there are any issues with accessibility or performance.
General Gas Furnace Inspection Steps
After assessing a furnace’s safety, sequence of operation, and location, an inspector will proceed with evaluating the following:
- Furnace Venting: The exterior of the flue, exhaust vent, and chimney is checked for corrosion, condensation, cracks, or blockages. The vent connector pipes are checked for proper installation, rust, loose connections, or damage, as well as proximity to combustible materials.
The gas vent pipe termination is also evaluated to ensure it meets established guidelines, including for height above the roof surface. Flashing must be installed at chimneys and gas vent pipes.
- Protective Barrier: A protective barrier must be installed near a furnace in a garage or other area where it could be damaged by a moving vehicle.
- Lighting: A light and a receptacle to power it should be located near the furnace.
- Disconnect Switch: The switch, electrical box, wire, and plate cover are inspected. An emergency shut-off switch should be located a safe distance from the furnace.
- Furnace Cabinet: The cabinet, its fasteners, and panels are inspected. Required clearances for combustion and service are checked per the manufacturer’s installation instructions. Generally, there should be at least 3 inches of working space around the cabinet.
For the next stage of the furnace inspection, the unit is turned off using the shut-off switch, so the cabinet panel can be removed. The inspector will then check the unit’s various components:
- Blower Door Switch/Control Board: The technician checks the blower door airlock switch (a safety switch), as well as for dirt on the blower housing, motor, fan blades, and wires. They also check the fan belt, fan rotation, and if the fan assembly is properly secured to the blower compartment (and for unusual noise or vibration while the fan is running). They check the main control board, transformer, wiring, and electrical junction box as well.
- Gas Shut-Off Valve: The gas valve should be within 6 feet of the furnace. In addition to checking the valve, the furnace inspector looks at the union downstream of it, the sediment trap, and the gas piping. If installed, a flexible connector cannot pass through the cabinet. Yellow-jacketed corrugated stainless steel tubing must be installed for electrical grounding protection.
- Gas Valve Assembly: To verify the system is running normally, the gas inlet is checked as the inspector operates the thermostat.
- Inducer Motor: While the system is running, the inducer fan motor and blower assembly are evaluated.
- Pressure Switches: Pressure switches and hoses are checked. A two-stage furnace may have more than one switch or hose.
- Condensate Trap: For condensing furnaces, the condensate trap and drainpipe are checked for any issues. The inspector may also look for an auxiliary drain pan. The condensate pump, if installed, is checked. If the furnace is in an attic, crawlspace, or other uninhabitable space, it’s verified the furnace can shut off automatically if the pump fails.
- Burners/Manifold: The gas pipe or tube between the valve assembly and burners is checked for signs of water, corrosion, or blockages. The burner ignition sequence is evaluated.
- Ignitor/Flame: The ignitor is checked for signs of corrosion or damage. Next, the inspector evaluates the flame sensor, flame roll-out switches and wires, and the ignition source. They also look for an erratic flame or other issues during operation.
- Electrical Components: All electrical components, wires, and connections are checked for issues and replaced or tightened as necessary.
- Air Distribution System: The contractor looks for vibration isolators between the furnace and metal ducts. Next, they check the air filter, accessible ductwork (for moisture or mold), ductwork insulation, and ductwork supports. They also look for loose sections, signs of air leakage, and improper sealing. Supply registers, grilles, diffusers, and dampers are checked for dirt.
Schedule a Furnace Inspection With Air Stars
A leading HVAC maintenance company in the Salem, OR, area, Air Stars has highly trained, licensed technicians who provide high-quality heating and cooling system maintenance. Our team can ensure your furnace is safe to operate, reliable, and energy-efficient. Members of our Star Treatment Maintenance Plan receive thorough system cleanings, inspections, and tune-ups every year. To request a furnace inspection, use our booking system or call (503) 744-5879.
