Furnace Maintenance and Repair 101

Furnace Maintenance and Repair 101

A furnace that’s not producing enough heat can ruin the cold months for you. Furnaces are an efficient way to heat your home, as they provide quick and powerful heating at a relatively low cost per month. It’s essential to take care of your furnace right now, so it works when you need it most. 

Cleaning and tuning a modern furnace is a more involved task compared to cleaning an old furnace. An old school clean and tune involved taking out the furnace’s pilot burner and cleaning the orifice, and then you’d remove rust from the main burner. Although these maintenance techniques were effective a decade ago, today’s high-efficiency furnaces call for more precise procedures to ensure peak performance. 

You already have to deal with frigid weather outside; you don’t need to deal with freezing weather inside of your home. To prevent furnace problems, follow these maintenance tips to help you clean and tune your furnace. 

Check the Igniter

Measure your furnace’s resistance by utilizing an igniter. If your furnace has a silicon nitride igniter, you should be able to read 11 to 17 ohms. If your furnace has a carbide igniter, you should see a reading of 50 to 100 ohms. Replace your igniter if your furnace’s resistance reading is outside of these parameters. To help you achieve a more accurate reading, make sure your furnace is turned off, and only test your furnace when the weather is cold. 

Test the Flame Sensor

Hook up your multimeter to your furnace’s flame sensor, then fire up your furnace in a heat cycle. Your readings should be approximately 1.5 to 4 uA (microamps), but some furnaces only need 0.5 uA. Check your furnace’s manual to determine the number of microamps your system needs. A sensor that tests at under 1uA usually experiences nuisance problems later on. Eventually, a troubled sensor stops sensing completely. Regularly checking your furnace’s flame sensor will help you keep your system in top condition. 

Clean the Burners

The most common issues associated with a furnace’s burners are misalignment and contamination. Several of today’s burner designs incorporate the carryover mechanism into the burner itself. Modern furnaces usually come with slots or “wings” in the burner, which align with the burner next to it. Inspect your burners to ensure they’re free from debris that could potentially disrupt air and gas flow. 

Use air pressure or dry nitrogen to blow out the burner’s vestibule area. Use a small, stiff-bristled brush to clean rust and superficial soot from the burner face. Burners declining in performance are a safety hazard because they’ll fill your home with high levels of carbon monoxide. Replace malfunctioning burners immediately. 

Examine the Heat Exchanger

Inspect your furnace’s heat exchanger for signs of wear, such as cracks, holes, and rust. You’ll also need to inspect your metal flue for rust and holes. Make sure your metal flue is adequately supported. To conduct a thorough heat exchanger inspection, you’ll need tools such as inspection cameras and a dye penetration inspection system. Don’t utilize these tools if you’re not trained in their usage.  

Blow out the Condensate Line

Remove or blow on your furnace’s P-trap and pressure tubes to remove debris. You must clean the P-trap and pressure tubes every few weeks because using your furnace for hours at a time during the cold can cause the pressure switch to lockout. 

Perform a Combustion Analysis

Remove your furnace’s combustion analyzer and place it outside of your house for proper calibration. Start your furnace and measure the highest carbon monoxide level upon start-up. Carbon monoxide readings should range from 100 to 400 ppm on a natural-draft furnace or 100 to 1,000 ppm on a 90% condensing furnace. Expect carbon monoxide levels to drop below 100 ppm after three minutes of booting up your furnace. If you notice your carbon monoxide levels rise during run cycles, you must address it for the safety of your family. 

Watch out for Gas Leaks

Check your furnace for gas leaks. You can use either an electronic leak detector or soap bubbles, but remember, some leak detectors produce a false-positive from certain brands of pipe dope. 

Common Furnace Problems and Repairs

Here are some of the most common problems your furnace might face:

  • Gas leaks: You’ll know your furnace is leaking if you can smell gas throughout your home. Avoid lighting any matches and turn off the gas supply valve, which is typically located by your gas meter. Evacuate your home. 
  • Pilot light keeps turning off: If your furnace’s pilot light refuses to stay lit, the thermocouple may be faulty. Another problem your furnace might be experiencing is a clogged pilot orifice. These are all jobs that should only be taken care of by a professional. 
  • Heating and cycling problems: Is your furnace still working, but not producing as much heat as it usually does? Verify nothing is obstructing the flow of warm air. Check your furnace’s filter; if the filter is dirty, replace it with a new air filter. 

Performing routine maintenance on your furnace should keep it in working condition for years to come. Unfortunately, some furnace problems are out of your control. Whether you need maintenance or repair for your central heating system, the technicians at Roberts Mechanical can provide both routine and emergency service. 

We’re based in Orem, and our technicians know how cold Utah’s winters are. After all, we’ve been living and serving Utah County for over three decades. Our certified specialists will get to the root of the issue so your home can remain warm. Contact Roberts Mechanical today.