Gas Furnace Troubleshooting and Repair | When to DIY or Call the Pros

how to fix a furnace - furnace troubleshootingOn those cold winter nights when the heat goes out, it can get pretty scary. Within a matter of hours, the house will be significantly colder, with the young and elderly suffering the worst of it. Time to get out some space heaters to delay the encroaching cold and begin the furnace troubleshooting process. The best way to avoid a malfunctioning furnace in the first place is to schedule professional heating maintenance every fall. Sign up for a home maintenance plan so you never forget this important home maintenance task.

Common Furnace Problems and How to Fix Them

Before you call the professionals, there are some quick things you should check first. Sometimes, all that is needed is a filter or battery replacement.

1. Thermostat Troubleshooting

Many times, when people think they have a broken furnace, it’s really a thermostat problem. Time to troubleshoot your thermostat:
Learn how a thermostat works from Mr. Wizard: [embed]
[/embed] If you do have any problems with your thermostat, don’t hesitate to contact Hiller. If you have checked all of the common thermostat problems and the furnace still isn’t working, it’s time to move on to the next steps.

2. Power

If your furnace isn’t getting power, go over to your breaker box and check for any blown fuses or tripped breakers. If power at the breaker/fuse box is on, make sure your HVAC system hasn’t been unplugged for any reason. There may also be a separate power switch near the furnace that looks like a light switch. Turn it on. After making sure everything is plugged in and switched on, reset power at your breaker box. If restoring the circuit doesn’t work, then you could have faulty wiring between your thermostat and furnace. If this is the case, call Hiller. If you have power, but the furnace is still not working properly, move on to step 3.

3. Dirty Air Filter

If both your thermostat and furnace are getting the power they need, the next thing to check is your furnace filter. Some HVAC systems have a safety device in place to turn off the furnace in the case of a dirty or clogged air filter. It’s important that you replace your HVAC filters every 30-90 days depending on the type of filter you have and how often you use your system. Changing your air filter improves airflow and indoor air quality while lowering heating costs and extending the lifespan of your unit. Watch this video to learn how to change your furnace filter (make sure the arrow is pointing in the direction of airflow):

4. Relight Pilot 

If your furnace has power and a clean air filter but still won’t work, there may be a problem with the gas. If you aren’t getting gas or the pilot won’t light, make sure the gas valve is fully open and the pilot light is fully depressed. If you need to relight your pilot, follow the manufacturer’s instructions exactly (hopefully the manual is fastened to the furnace somewhere). If you can’t find the exact instructions, follow these steps:

Bad Pilot Signs

You can adjust your pilot light flame height by tightening or loosening the screw located on the pilot valve body. Refer to your manufacturer instructions for proper location. Tightening the screw (clockwise) should decrease the flame size while loosening the screw (counter clockwise) should increase it. If your pilot light won’t stay lit or is any other color than blue, call the professionals at Hiller to diagnose the situation. You may have a dangerous combustion situation or a faulty thermocouple (safety device that shuts off the gas). Sometimes, to fix the thermocouple, all you need to do is tighten the nut with a wrench. Be careful not to over-tighten! Only tighten it a little bit. Then, try to light the pilot again. If tightening the thermocouple nut doesn't work, you probably need to replace the thermocouple. This is a fairly easy repair, but unless you know exactly what you are doing, we recommend calling a pro.

5. Cleaning, Lubrication, and General Maintenance

The best way to avoid furnace problems in the first place is with regular maintenance. Most heating maintenance is accomplished by remembering to schedule a professional tune-up in the fall (or signing up for a home maintenance plan) and replacing your air filters every 30-90 days. Your technician will lubricate all moving parts, clean the insides and outsides, as well as checking for venting and electrical safety. The technician will clean off all the dust and dirt that have accumulated over the summer, as well as sealing and leaks and tightening bolts hold any components in place. If there’s a bigger problem brewing, he can spot it and schedule a repair session; he’ll also run the heater to ensure that everything is functioning as it should. This helps the heater use less energy in the winter months, reducing your bills as well as running less of a risk of major repairs. These are things you should not attempt to DIY. Read our Air Filtration Guide to learn more about the importance of HVAC filters.
To recap the furnace troubleshooting process:
  1. Check your thermostat
  2. Check for power
  3. Replace the air filter
  4. Relight pilot light
  5. Make sure all vents and registers are unblocked
  6. Make sure access panel doors are fully closed
  7. Restart your furnace

A photo posted by Hiller PHCE (@happyhiller) on Dec 11, 2016 at 10:32am PST

When to Call the Professionals

Although some malfunctions are obvious—such as a furnace that won’t turn on at all—others are a bit harder to diagnose, such as changes in the sound the furnace is making. Below are some of the warning sounds that your furnace needs professional assistance you shouldn’t let slip by. Because there can be more than one cause behind a particular furnace noise, you will need repair technicians to diagnose the problem first and then apply the right solution. The dangers of DIY furnace repair include fire, carbon monoxide poisoning, refrigerant leaks, and expensive repairs. If you have any doubts about what you are doing, stop and call a professional. Troubleshooting the issue on your own is extremely risky, so don’t attempt it: just contact the award-winning team at Hiller. We are familiar with all makes and models and can get your heat back in no time.

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Hiller Plumbing, Heating, Cooling, & Electrical provides residential and commercial service and repair throughout Tennessee, Southern Kentucky, and Northern Alabama. Contact Hiller Plumbing, Heating, Cooling, & Electrical for professional HVAC maintenance, repairs, and replacements. Keep up with all of our news and tips by following us on FacebookTwitter, Google+, Instagram, LinkedIn, and Pinterest. We are available 24/7 to help with any plumbing, heating, or electrical problems you may have (holidays included).