Foolproof Furnace Maintenance

     

Take good care of a furnace, and it will work efficiently and cost-effectively for many years. Learn how to properly maintain a furnace as well as how each step contributes to the overall health and longevity of the unit.

A well-maintained furnace should last a decade, maybe two. For multifamily communities, regular maintenance is the single most important factor in getting the most out of every furnace on a property. Not only will annual furnace maintenance cut down on emergency calls, but annual furnace checkups will also identify small or potential issues before they become big problems.

When it comes to furnace maintenance in a multifamily community, how much is enough, especially when the maintenance team is balancing all the other necessary work on the property? Every furnace should be serviced at least once each year. This annual maintenance check should include:

• A visual inspection of the unit
• Cleaning or replacing air filters
• Checking the burner or heat exchanger
• Testing switches and electrical connections
• Ensuring proper furnace operation (heating, current flow, venting)

To help maintenance teams keep their furnaces protected and working properly, our furnace experts put together an easy-to-follow plan that explains what to do and why it’s an important factor in prolonging the life of every furnace on the property.

Key Furnace Components Include

Furnace Maintenance Checklist

NOTE: This maintenance checklist applies to 80% gas furnaces.

Annual furnace maintenance is a two-step process. First, check that all components are clean and undamaged. Then, run the furnace to test its function and measure key indicators of system health.

• □  Cabinet – Clean and free of soot, rust, or structural damage.
• □  Thermostat – Wired correctly, getting power, operating properly. If the t-stat is not calling for heat, nothing down the line will work.
• □  Filter – Clean or replace as needed. Dirty filters reduce operational efficiency and shorten the life of a furnace.
• □  Phasing and Polarity – Ensure voltage is correct, polarity is not reversed.
• Correct voltage should be between 92 and 97 volts
• Reversed polarity will read about 150v
• □  Control Board – Check connections and dip switches.
• □  Burner Assembly – Clean, free of debris, plates in proper position.
• Moisture and debris on the plate will not allow the flame to continue from burner to burner.
• Damage to burner plates or too much of a pilot gap will cause the flame to fail to light all burners, limiting furnace function.
• □  Spark Ignitor – Check the porcelain and solid wire for any cracks, holes, or other issues.
• If damaged, the ignitor may not spark.
• Ohm check for infinite resistance.
• □  Hot Surface Igniter – Inspect surface condition, look for cracks, test ohms with a multimeter.
• □  Gas Valve – Test pressures, adjust if necessary. Proper gas pressure plays a vital role in furnace operation.
• □  Heat Exchanger – Clean and free of cracks, holes, moisture, or leaks.
• Check for condensation where the heat exchanger connects with the vent pipe.
• Condensation is a sign of poor system performance.
• □  Blower and Motor – Clean, undamaged, and operating properly.
• □  Inducer Wheel – Fins are in good order and free of rust. Rust is an indication of improper combustion and/or low combustion air.
• □  Electrical – All wiring is connected properly and not scorched.
• □  Switches – All switches (pressure, vent, and limit) are in good condition and working properly.
• Wiring is clean and tight
• Tubing connected with the pressure switch is clean, pliable, and not cracked
• □  Gas Line – Line and all components are in good condition and free of damage or leaks.
• □  Flame Sensing Rod, aka “Rectifier” or “Rectification Rod” – Clean and properly positioned, with one end in contact with the burner flame and the other connected to the ignition board.
• Current travels down the rod to indicate a flame.
• A dirty or damaged rectifier may cause a signal fault.
• If a rectifier is touching the chassis of the furnace this will cause an error code.
• □  Flue Vent, Pipe, and Duct – Free of clogs, corrosion, condensation, or damage.
• Damage to ductwork will reduce the furnace’s natural draft, reducing efficiency.
• Moisture (condensation) in the flue is an indication of poor system performance.
• □  Pilot Light – (If present) clean the pilot system.

Once the furnace component check is complete, run the system to ensure everything is operating properly. Check the flame current, pressures, and temperature rise (see below).

Testing Temperature Rise

Temperature rise is the difference in the air temperature entering the furnace (return) and the air temperature leaving the furnace to warm the living space (supply). Temperature rise is a very important indicator of overall furnace health. Maintaining proper rise will prevent short cycling and tripping the high limit. To measure a furnace’s temperature rise:

1. Measure and record the return air temperature
2. Measure and record the supply air temperature
3. Subtract the return temp from the supply temp
4. The difference is the temperature rise

Check the output against the manufacturer’s acceptable range for that unit, which will be noted on the furnace’s rating (data) plate. If the temperature rise is:

Too High? The air may be flowing too slowly, try:

• Raising the fan speed
• Lessening static pressure
• Decreasing gas pressure
• IMPORTANT: Pressure norms are different for natural gas and liquid propane, these will be noted on the rating (data) plate

Too low? The air may be flowing too quickly, try:

• Lowering fan speed
• Increasing gas pressure
• Adjusting duct static pressure

Efficiency Check

Adequate ventilation is necessary for proper furnace operation. Complete your furnace maintenance check with a visual review of the furnace room door. Door louvers should be open, clean, and free of obstructions that might impede air flow.